Research into the Investment Casting Process & Materials

The following are a collection of technical papers that have been produced by Remet to explore in detail the issues of relevance to the precision investment casting foundry.

Targeted to aid process and part engineers, Remet’s technical papers serve as a reference point for the investment casting technical community. Providing information on the research undertaken in both our North American and European laboratories, the below papers present studies into the advanced materials used within today’s modern investment casting foundry. In addition to this, there are also papers discussing the prevention of casting defects and practices of process control.

Many of the articles have been presented at various technical conference hosted by organisations such as the Investment Casting Institute, European Investment Caster’s Federation and the Japanese Foundry Society. If there is a specific paper you are looking for and cannot find please contact us.

Non Silica Binder System

P-39 Casting of Reactive Alloys: An Update of Current Technology

Charles H. Matzek, June 1997

 

Presented at the Cannon-Muskegon Technology Conference in Conjunction with The Paris Air Show

 

Casting quality is an important issue to all foundries. The quality of the casting is, at best, only as good as that of the wax pattern. Nothing used in the investment casting process stands by itself from the standpoint of affecting the final quality. Eery component used in the process ƒ€“ the wax, the pattern cleaner, the face coat binder and refractories, the backup binders and refractories, the metal, the crucibles and transfer ladles ƒ€“ interacts with and is affected by the other components. Process controls or, more often, the lack of proper controls has additional impact on quality. Everything the foundryman does in his selection of process conditions, processing controls and raw material selection is directed towards keeping the quality of the finished casting as high as possible. These issues are especially important to those foundries casting reactive alloys. Reactive alloys add another dimension to the problem because the foundry must now have face coats, cores and crucibles/transfer ladles which will not react with the metal during melting, transfer, pouring and cooling.

 

REMET CORPORATION has had a long term interest and involvement in the development of face coats for use with reactive alloys. Research in this has resulted in numerous papers and Patents. This area of research continues to be actively pursued by REMET CORPORATION today. The purpose of this Paper is to provide a summary of what has been done as well as to provide an overview of those areas in which REMET CORPORATION continues to be active. This presentation is not meant to provide a ƒ€œrecipeƒ€ which a foundry can follow. Conditions vary too much for that to be a practical goal. Rather it is most important that each of you in the audience realize that this is an active area and that there are resources available to you to help you be successful.

P-5 Casting of Reactive Metals into Ceramic Molds

R. Chester Feagin, October 1984

Presented at the 6th World Conference on Investment Casting

This paper describes the results of casting titanium and other reactive metals into experimental ceramic mold systems under controlled conditions. Photomicrographs of metalographic sections show relative degrees of reactivity. Certain specific mold systems are recommended for further study.

P-4 Casting of Reactive Alloys: An Update of Current Technology

Charles H. Matzek, June, 1997

 

Presented at the Cannon-Muskegon Technology Conference in Conjunction with The Paris Air Show

 

Casting quality is an important issue to all foundries. The quality of the casting is, at best, only as good as that of the wax pattern. Nothing used in the investment casting process stands by itself from the standpoint of affecting the final quality. Every component used in the process ƒ€“ the wax, the pattern cleaner, the face coat binder and refractories, the backup binders and refractories, the metal, the crucibles and transfer ladles ƒ€“ interacts with and is affected by the other components. Process controls or, more often, the lack of proper controls has additional impact on quality. Everything the foundryman does in his selection of process conditions, processing controls and raw material selection is directed towards keeping the quality of the finished casting as high as possible. These issues are especially important to those foundries casting reactive alloys. Reactive alloys add another dimension to the problem because the foundry must now have face coats, cores and crucibles/transfer ladles which will not react with the metal during melting, transfer, pouring and cooling.

Alumina and Zirconia Binders

Alternative Binders for Investment Casting

 

R. Chester Feagin, October 1981

Presented at the 29th Annual Meeting of the Investment Casting Institute, October 1981

 

This paper discusses the chemical properties and bonding characteristics of new commercially available binders of aqueous colloidal alumina monohydrate and zirconium oxide.

Potential applications are indicated together with some physical property data derived from bonded refractory systems.

Ethyl Silicate Binder

P-42 Comparison Of Properties Of Zircon/Alumino-Silicate Shells With Water-Based And Ethyl Silicate-Based Binders

Manuel Guerra, Jr. ,ƒ‚ May 1998

 

Presented at the 24th EICF Conference in Rome, Italy

 

Two polymer-enhanced, colloidal silica binders (both large and small particle sols) were compared against an alcohol hybrid binder system. The three binders were used with a Zircon and 60% alumina, alumino-silicate flour blend, with Molochite stucco. All of the systems were tested for:green MOR, hot MOR, fired MOR, high temperature creep, and thermal expansion. The hybrid binder had the highest overall MOR strength, but some of this difference could be due to the processing conditions (50-55% RH), which were somewhat more favorable to an alcohol system. There were only minor differences in the creep and thermal expansion results.

P-31 REMASOLƒ‚® ADBONDƒ‚® BV: A Practical Update

James R. Pyne, June 1994

 

Presented to the E. I. C. F. Conference, Prague

 

The REMASOLƒ‚® ADBONDƒ‚® BV system was introduced to the U. S. market in late 1992. It was developed with the goal of replacing Ethyl Silicate as a binder. Several key objectives were established at the outset of the program. These included:

 

  • be an environmentally acceptable binder
  • be usable with all standard refractories
  • process as rapidly as ethyl silicate bonded shell systems.

 

Initially, REMET’s direction was to look at only ethyl silicate replacement situations. The market opened our eyes to the productivity improvement needs of foundries which were using non-polymer modified Colloidal Silica bonded shell systems. Very simply, the REMASOL ADBOND BV systems offered improvements to foundries regardless of which binder system they were currently using.

 

The purpose of this paper is to provide you with some practical foundry experiences based upon the more than 35 foundries who have already converted to the REMASOL ADBOND BV system so that you can better judge the potential value which it can provide to you in your particular production situation.

P-30 REMASOLƒ‚® ADBONDƒ‚® BV: A Practical Update

Charles H. Matzek, February 1994

 

Presented to Verein Deutscher GieƒƒŸereifachleute (VDG)

 

The REMASOLƒ‚® ADBONDƒ‚® BV system was introduced to the U. S. market in late 1992. It was developed with the goal of replacing Ethyl Silicate as a binder. Several key goals were established at the outset of the program. These include:

 

  • be an environmentally acceptable binder
  • be usable with all standard refractories
  • process as rapidly as ethyl silicate bonded shell systems.

 

Initially, REMET’s direction was to look at only ethyl silicate replacement situations. The market opened our eyes to the productivity improvement needs of foundries which were using non-latex modified Colloidal Silica bonded shell systems. Very simply, the REMASOL ADBOND BV systems offered improvements to foundries regardless of which binder system they were currently using. The purpose of this paper is to provide some practical foundry experiences based upon the more than 30 foundries who have already converted to the REMASOL ADBOND BV system so that you can better judge the potential value which it can provide to you in your particular production situation.

P-29 REMASOLƒ‚® ADBONDƒ‚® BV Binder – An Update

Manuel Guerra,ƒ‚ June 1993

 

Presented at the 8th World Conference on Investment Casting,

 

REMASOLƒ‚® ADBONDƒ‚® BV binder was introduced to the Precision Investment Casting industry in October 1992 as a backup binder. The product has now been used in production and many foundries have discovered that REMASOLƒ‚® ADBONDƒ‚® BV does provide for significantly faster shell processing time versus standard colloidal silica, to the point where it can equal alcohol-based binder systems.

 

This paper is an update to the original paper presented in 1992 at the 40th ICI Conference in Las Vegas, Nevada. Additional information on MOLOCHITEƒ„ refractory with a REMASOLƒ‚® ADBONDƒ‚® BV system, and the effect of diluting the binder percent silica of a REMASOLƒ‚® ADBONDƒ‚® BV system are shown.

P-28 REMASOLƒ‚® ADBONDƒ‚® B and REMASOLƒ‚® ADBONDƒ‚® BV Binders

Manuel Guerra,ƒ‚ October 1992

 

Presented at the 40th Annual Meeting of the Investment Casting Institute,

 

The ethyl silicate bonded shell process is under environmental and cost pressure worldwide. Alternative polymer containing binder systems, which claim to approach the speed of ethyl silicate, require expensive, specially sized fused silica refractories. Frequently, fused silica cannot be used because of shell expansion and other considerations versus the refractory system currently in place.

 

REMASOLƒ‚® ADBONDƒ‚® B and REMASOLƒ‚® ADBONDƒ‚® BV binders allows the investment casting foundry to achieve drying rates comparable to ethyl silicate while using any standard refractory.

P-19 Hot Modulus of Rupture Measurements on Some Aluminosilicate Shell Systems

R. Chester Feagin,ƒ‚ June 1980

 

Presented at 28th Annual Meeting of the Investment Casting Institute, October 1980 and at the 5th World Conference on Investment Casting, June 1980

 

For the past three years we have been involved in the evaluation of aluminosilicate refractories in various shell systems. This work involves the preparation of shell test specimens in which the first two coats utilize zircon refractory, which is common practice for many shell systems, and the remainder of the shell being totally aluminosilicate refractory both in the slurry and stuccos. Colloidal silica was the major binder evaluated using a prehydrolyzed hybrid REMET A-1 binder containing 20% SiO2. These shell systems were evaluated for modulus of rupture at room temperature in the unfired state after drying, and after firing to temperatures of 649ƒ‚°C, 927ƒ‚°C and 1093ƒ‚°C and then cooling to room temperature. Thermal expansion measurements were run on three shell systems, and hot modulus of rupture measurements at 1371ƒ‚°C were determined on most of the shell series. Results of the room temperature and hot modulus of rupture measurements and thermal expansions are presented with discussion.

P-16 Ethyl Silicate Shell Systems

R. Chester Feagin, October 1979

 

Presented at 27 Annual Meeting of the Investment Casting Institute

 

This paper reports on the continuation of some work on aluminosilicate shell systems in which ethyl silicate binders are used. Some work on aluminosilicate shell systems has previously been reported. (1) (2) Modulus of Rupture (MOR) data were presented on aluminosilicate shell systems using colloidal silica binders showing the influences of slurry refractory particle size, colloidal silica particle size, and silica concentration, type of aluminosilicate, and fused silica additions to aluminosilicate shells on MOR and thermal expansion.

 

This paper is a continuation of work on aluminosilicates in shell systems. A fused silica shell system is used as a base with substitutions of zircon and aluminosilicates as slurry and stucco refractories. Commercially available prehydrolyzed ethyl silicate and hybrid ethyl silicate binders at ten and twenty weight percent silica were used in the slurries. Some MOR data at room and 1750ƒ‚°F temperatures, and thermal expansion data to 1832ƒ‚°F (1000ƒ‚°C) are presented. Although this study is primarily a continuation of work on REMASILƒ‚® 60, a highly refractory material, for shell application, these data have particular significance in view of recent shortages of fused silica. Much work still has to be done such as more data on binder silica contents and types, hot MOR and thermal expansion. However, we have determined some areas of interest by laboratory test specimens, which will require practical castings confirmation.

Reactive Alloy Casting

A Practical Guide to Successful Investment Casting of Titanium Alloys

Compiling a Successful Solution for Reactive Alloy Casting

 

Charles H. Matzek

Presented by Manuel Guerra Jr. at the ICI 12th World Conference, October 2008, Dallas, TX

 

The investment casting of titanium alloys is growing in importance and economic value.ƒ‚ The reactive nature of these alloys forces the foundry to be more critical in selecting the key materials ƒ€“ the pattern and runner waxes, and the primary and second coat binders, flours and stuccos ƒ€“ used in the process.ƒ‚ This paper reviews Wax, Binder and Refractory options available to the investment caster, discusses the factors to be considered when making the selection and provides system recommendations that will enable a foundry to begin investment casting of titanium alloys.

P-39 Casting of Reactive Alloys: An Update of Current Technology

Charles H. Matzek, June 1997

 

Presented at the Cannon-Muskegon Technology Conference in Conjunction with The Paris Air Show

 

Casting quality is an important issue to all foundries. The quality of the casting is, at best, only as good as that of the wax pattern. Nothing used in the investment casting process stands by itself from the standpoint of affecting the final quality. Eery component used in the process ƒ€“ the wax, the pattern cleaner, the face coat binder and refractories, the backup binders and refractories, the metal, the crucibles and transfer ladles ƒ€“ interacts with and is affected by the other components. Process controls or, more often, the lack of proper controls has additional impact on quality. Everything the foundryman does in his selection of process conditions, processing controls and raw material selection is directed towards keeping the quality of the finished casting as high as possible. These issues are especially important to those foundries casting reactive alloys. Reactive alloys add another dimension to the problem because the foundry must now have face coats, cores and crucibles/transfer ladles which will not react with the metal during melting, transfer, pouring and cooling.

 

REMET CORPORATION has had a long term interest and involvement in the development of face coats for use with reactive alloys. Research in this has resulted in numerous papers and Patents. This area of research continues to be actively pursued by REMET CORPORATION today. The purpose of this Paper is to provide a summary of what has been done as well as to provide an overview of those areas in which REMET CORPORATION continues to be active. This presentation is not meant to provide a ƒ€œrecipeƒ€ which a foundry can follow. Conditions vary too much for that to be a practical goal. Rather it is most important that each of you in the audience realize that this is an active area and that there are resources available to you to help you be successful.

P-26 Refractory Selection for Primary Shell Coat

Glenn W. Schiefelbein, May 1994

 

Presented at Cannon-Muskegon Seminar, May 1994 and Investment Casting Institute Meeting, September 1994

 

A discussion of two major considerations when selecting a primary coat refractory.

 

  1. It must be non-reactive with the binder to produce a stable user friendly slurry.
  2. I must also be non-reactive with the alloy being poured. I will describe metal-refractory reactions. In order to understand these reactions, we must examine the nature and behavior of these refractories.

P-25 Refractories Used for Investment Casting of High-Temperature Alloys

Manuel Guerra

 

Alumina refractories play a key role in contemporary precision investment casting. As one of the main constituents in shell molds for high-temperature alloys, alumina is favored because of its chemical inertness and high-temperature capability. This chapter summarizes the principal physical and chemical characteristics of alumina in relation to the requirements for its use in both the slurry and stucco components of typical shell molds. Particular attention is given to factors affecting slurry stability and shell strength. Other applications for alumina in investment casting, including crucibles, alloy filters and mold insulating warp are briefly reviewed. The current trend to increasing process temperatures dictated by advances in directional solidification technology, points to expanded use of alumina refractories in the investment casting of high-temperature alloys.

P-5 Casting of Reactive Metals into Ceramic Molds

R. Chester Feagin, October 1984

Presented at the 6th World Conference on Investment Casting

This paper describes the results of casting titanium and other reactive metals into experimental ceramic mold systems under controlled conditions. Photomicrographs of metalographic sections show relative degrees of reactivity. Certain specific mold systems are recommended for further study.

P-4 Casting of Reactive Alloys: An Update of Current Technology

Charles H. Matzek, June, 1997

 

Presented at the Cannon-Muskegon Technology Conference in Conjunction with The Paris Air Show

 

Casting quality is an important issue to all foundries. The quality of the casting is, at best, only as good as that of the wax pattern. Nothing used in the investment casting process stands by itself from the standpoint of affecting the final quality. Every component used in the process ƒ€“ the wax, the pattern cleaner, the face coat binder and refractories, the backup binders and refractories, the metal, the crucibles and transfer ladles ƒ€“ interacts with and is affected by the other components. Process controls or, more often, the lack of proper controls has additional impact on quality. Everything the foundryman does in his selection of process conditions, processing controls and raw material selection is directed towards keeping the quality of the finished casting as high as possible. These issues are especially important to those foundries casting reactive alloys. Reactive alloys add another dimension to the problem because the foundry must now have face coats, cores and crucibles/transfer ladles which will not react with the metal during melting, transfer, pouring and cooling.

Wax

P 71 – Investigating the Behaviour of Casting Wax During the Autoclave Process

Previously we have reported on the use of controlled stress rheometry (alongside DMA and DSC) as a method for investigating the behavior of casting waxes during the injection and subsequent cooling processes.

This paper reports the use of temperature ramped controlled stress rheometry (yield measurement) and temperature controlled FTIR to investigate the behavior of wax during the autoclave process. Drawing on results obtained from Birmingham (UK) University’s FOCAST (Fundamentals Of investment CASTing) programme, experiments have been carried out to investigate factors affecting the flow and absorption characteristics of wax at the shell/wax interface during the early stages of the autoclave process. Results are reported focusing on the variation in time and temperature response of various waxes, and the potential effects upon the dewax process.

Originally presented to the 61st ICI Conference & Equipment Expo.

AUTHOR: Dr. Grant Bradley (REMET UK)

Water Soluble Cores for Investment Casting

Improving Surface Finish & Dimensional Consistency in the use of Cores

 

Marcelo Anibarro,

Presented at the 55th Indian Foundry Congress 2007

 

It is the intent of this paper to provide the foundryman with a broader understanding of soluble cores from a functionality standpoint by reviewing their chemistry and analyzing their physical/chemical behavior in the foundry. In addition, guidelines will be provided to enhance surface finish, dimensional consistency, and dissolution characteristics that in turn could help generate a better pattern wax and thus a better final casting.

An Overview of the Rheology of Investment Casting Waxes

New Assessment Method Offering Greater Insight for Injection & Dewax Processes

 

Marcelo Aƒƒnibarro,

Presented at the Investment Casting Institute 49th Annual Technical Meeting 2001

 

Remet is evaluating a new method for evaluating the rheological properties of its waxes on both a heating and cooling basis with the aim of providing a greater insight into wax performance under injection and dewax conditions. This paper describes the testing that has been done to date and provides interpretative comments regarding wax performance in the foundry.

Wax Characterization

Wax Components & their Effect on the Investment Casting Process

 

Jeffrey Niles, Marcelo Anibarro and Harvey Fielder

Presented at the ICI 50th Technical Conference and Expo, Chicago, IL October 2002

 

Precision investment casting waxes are a complex blend of several different carefully selected ingredients. Fillers, additives, resins, microcrystalline and paraffin waxes are used to develop the desired wax to meet the specific requirements of the investment caster. The blend is then analyzed and the results are used to characterize the end product. This paper will look at the various properties that are tested and evaluated. The different properties of a wax will be explained in detail, with an emphasis on how each property influences the investment casting process. In addition, the interaction that occurs at the wax/primary slurry interface will be discussed.

Health and Safety Aspects of Investment Casting Waxes

Considerations for these Materials & their Use

 

Harvey Fielder,

Technical Service Manager, Remet UK Ltd.

 

In todayƒ€™s safety conscious workplace it is vital that end users of chemicals, and blends thereof, are fully aware of any hazards inherent in the materials utilized in their operations. Only with this knowledge can they take suitable precautions to eliminate or minimize the risks involved to personnel and the environment.

Wax based blends are an essential part of the investment casting process. They are generally complex mixtures of natural and synthetic organic compounds and can present a variety of health hazards if handled incorrectly. In this paper, the author takes a detailed look at the health and safety aspects of these materials, focusing on the physical and chemical hazards they can present in the wax room and the handling and processing techniques necessary to counter them.

P-47 The Reclamation of Investment Casting Waxes

Explanation of the Process & Performance of Reclaim Waxes

 

Harvey Fielder,

Remet UK Ltd. and presented at the World Conference, Monte Carlo in 2000.

 

In this paper the author considers the various wax reclamation techniques in use today. By focusing on the methods used by Remet UK Ltd. , he gives a detailed description of how wax returned from the foundry can be dried, cleaned and processed to yield a variety of cost effective, reclaim based products. In many cases these products have performance characteristics that rival those of virgin waxes.

The paper considers the technical quality of these reclaim based products and also reflects on the steps a foundry can take to help the wax reclaimer make the best of the wax returned for reprocessing.

P-46 Mechanical Properties of Pattern Waxes

Harvey Fielder,

 

Dussek Campbell Ltd. (Yates Investment Casting Wax Division), Crayford, Kent, UK

 

In this paper the author outlines a method that generates data directly applicable to the wax room. The mechanical properties of casting waxes play a vital part in the investment casting process. Patterns must be sufficiently tough to resist breakage during assembly and must not distort if dimensional tolerances are to be maintained. Equally, runner bars must not fracture or sag when assemblies are handled by robot dipping lines.

The Effect of Fillers on the Physical Properties of Investment Casting Waxes

A Study into the Volumetric Sinkage of an Injected Part

 

Harvey Fielder,

Remet (Dussek Campbell Yates Ltd. ), Crayford, Kent, UK

 

In the early days of modern investment casting, unfilled, or ƒ€œstraightƒ€, pattern waxes were successfully used to produce parts of the desired quality. As the demand for larger, more complex and tightly dimensioned castings grew, however, the performance limitations exhibited by unfilled waxes led to the development of filled pattern waxes.

P-44 Flow and Deformation of Casting Waxes in the Solidification Region

Dr. H. Monks,

 

Dussek Campbell (UK) Ltd. , 8th World Conference on Investment Casting

 

It is common practice to quote the viscosities of molten casting waxes at various temperatures. However it is exceedingly difficult to measure their viscosity at or near the congealing point using conventional techniques . Furthermore, it is questionable whether viscosity alone is sufficient to characterize the fluid properties of these materials in the region of interest. It is assumed that a knowledge of the fluid properties in the solidification region will assist in the improvement of patterns and pattern production by better informing designers of waxes, moulds, and even injection machines. This paper considers the techniques available to the researcher in this field, and in particular, examines one of these techniques in some detail. The results presented are intended to demonstrate the scope of the method and provide some preliminary results with commercially available casting waxes. The broad conclusion reached is that much useful information is generated, and further studies recommended.

P-43 Investment Casting Analysis Past, Present and Future

A. Barker, M. Sc,

 

Dussek Campbell Ltd. , Crayford, Kent, UK

 

Investment casting analysis has expanded from the use of the human eye and evaluation of waxes by ashing, to the use of light microscopy and, now, electron microscopy (for photography and elemental analysis of problems). The use of atomic absorption spectroscopy for metal contamination analysis has been advanced by the use of plasma emission and now by a direct and sensitive X-ray fluorescence technique. Problems with raw materials can be investigated using various chromatographic means. Casting waxes can now be characterized by a multiplicity of techniques such as infrared spectroscopy, rheology, particle size analysis and thermo-mechanical analysis to produce better products.

Shell Systems

Strategies to Manage Zircon Usage in Times of Market Upheaval

Alternative Materials & Strategies to Reduce the Investment Casting Industry’s Reliance on Zircon

 

Manuel Guerra Jr., Frank Tistle, and John Siedlecki

Presented by Frank Tistle at the 58th ICI Technical Conference and Equipment Expo, October 2011. Cincinnati, OH

 

Since mid-2010, the zircon market has experienced another volatile periods of supply and demand leading to price spikes and material allocations, making it difficult for foundries to accurately plan production and price castings. Foundries are re-evaluating their processes with a goal of reducing or eliminating zircon usage to minimize or eliminate their exposure to this volatile market. This paper will discuss testing performed on different refractory materials and binder systems to identify viable and economical zircon sand and flour substitutes.

Ceramic Shell Drying | Investment Casting Defects | Remet

Reducing Delays Effecting Productivity, Scrap & Rework

 

Manuel Guerra,

Presented at the ICI 57th Technical Conference & Expo 2010

 

The drying of recessed areas can contribute to significant time delays in the processing of shell molds, as well as leading to rework and scrap issues. This paper will present data from various testing to evaluate the effect of different binders (polymer and non-polymer) to try to overcome this all too common problem.

A Practical Guide to Successful Investment Casting of Titanium Alloys

Compiling a Successful Solution for Reactive Alloy Casting

 

Charles H. Matzek

Presented by Manuel Guerra Jr. at the ICI 12th World Conference, October 2008, Dallas, TX

 

The investment casting of titanium alloys is growing in importance and economic value.ƒ‚ The reactive nature of these alloys forces the foundry to be more critical in selecting the key materials ƒ€“ the pattern and runner waxes, and the primary and second coat binders, flours and stuccos ƒ€“ used in the process.ƒ‚ This paper reviews Wax, Binder and Refractory options available to the investment caster, discusses the factors to be considered when making the selection and provides system recommendations that will enable a foundry to begin investment casting of titanium alloys.

Reducing Zircon Sand Usage

REMASIL® 60 RG 100 A Replacement Refractory for Zircon

 

Manuel Guerra, Jr.

Presented at the Investment Casting Institute 54th Technical Conference & Expo 2006

 

Abstract: A new material, which has the potential to replace zircon sand for secondary prime dips, and possibly the first prime for some casters, has been developed. REMASILƒ‚® 60 RG100, based on a 60% alumina, alumino-silicate material, is a high Mullite product which has been fired to a high temperature. It is then sized to provide the optimum match to zircon sand (the distribution is slightly coarser than zircon. ) Laboratory testing (MOR, permeability and thermal expansion) was performed to determine how closely the RG100 sand performed versus zircon. The test results revealed some small differences between the two sands. The method of application (fluid bed or rainfall sander) resulted in only minor differences in the permeability or MOR results.

P-42 Comparison Of Properties Of Zircon/Alumino-Silicate Shells With Water-Based And Ethyl Silicate-Based Binders

Manuel Guerra, Jr. ,ƒ‚ May 1998

 

Presented at the 24th EICF Conference in Rome, Italy

 

Two polymer-enhanced, colloidal silica binders (both large and small particle sols) were compared against an alcohol hybrid binder system. The three binders were used with a Zircon and 60% alumina, alumino-silicate flour blend, with Molochite stucco. All of the systems were tested for:green MOR, hot MOR, fired MOR, high temperature creep, and thermal expansion. The hybrid binder had the highest overall MOR strength, but some of this difference could be due to the processing conditions (50-55% RH), which were somewhat more favorable to an alcohol system. There were only minor differences in the creep and thermal expansion results.

P-41 The Effect of Particle Size of Fused Silica Flour on Shell Properties

Jeffrey C. Niles, September 1997

 

Presented at the ICI 45th Annual Technical Meeting, Atlanta GA, September, 1997

 

This study evaluated the effect that particle size of fused silica flour has on shell properties. Three different flour sizings were tested (-120, -200 and ƒ€“270 mesh sizings) with REMASOL SP-30 colloidal silica (diluted to 26% silica solids) and both fused silica stucco (30 x 50 mesh) and aluminosilicate stucco (20 x 40 mesh). The test results include green, hot and fired MOR, hot permeability, thermal expansion and high temperature creep.

P-40 Slurry Development and Control

Julian G. Kovacs, August 1997

 

Most foundries’ success is dependent on the foundry men’s intelligent choice of materials to their shell development and on the particular control of the variables in the process that they have established in their operation.

 

This paper attempts to provide some guidelines to the foundry men about the material selection available for making reliable slurries and to assist them in setting up control parameters for the slurry process. Some practical suggestions about mixing slurries and drying shells will also be included.

 

The selection of binders, refractories and other components of slurries will be discussed. Slurry preparation, mixing, maintenance and testing will also be reviewed.

P-39 Casting of Reactive Alloys: An Update of Current Technology

Charles H. Matzek, June 1997

 

Presented at the Cannon-Muskegon Technology Conference in Conjunction with The Paris Air Show

 

Casting quality is an important issue to all foundries. The quality of the casting is, at best, only as good as that of the wax pattern. Nothing used in the investment casting process stands by itself from the standpoint of affecting the final quality. Eery component used in the process ƒ€“ the wax, the pattern cleaner, the face coat binder and refractories, the backup binders and refractories, the metal, the crucibles and transfer ladles ƒ€“ interacts with and is affected by the other components. Process controls or, more often, the lack of proper controls has additional impact on quality. Everything the foundryman does in his selection of process conditions, processing controls and raw material selection is directed towards keeping the quality of the finished casting as high as possible. These issues are especially important to those foundries casting reactive alloys. Reactive alloys add another dimension to the problem because the foundry must now have face coats, cores and crucibles/transfer ladles which will not react with the metal during melting, transfer, pouring and cooling.

 

REMET CORPORATION has had a long term interest and involvement in the development of face coats for use with reactive alloys. Research in this has resulted in numerous papers and Patents. This area of research continues to be actively pursued by REMET CORPORATION today. The purpose of this Paper is to provide a summary of what has been done as well as to provide an overview of those areas in which REMET CORPORATION continues to be active. This presentation is not meant to provide a ƒ€œrecipeƒ€ which a foundry can follow. Conditions vary too much for that to be a practical goal. Rather it is most important that each of you in the audience realize that this is an active area and that there are resources available to you to help you be successful.

P-36 Using Stucco More Effectively

Charles H. Matzek, February 1988

 

Modern Casting

 

A proper stucco program is essential in order to successfully make a shell which will yield a high quality investment casting. The stucco program involves the choice of the proper stucco size for each coat, using stucco materials which have a tightly controlled particle size distribution and proper maintenance of the stucco application equipment.

P-34 Titanium Investment Casting

R. Chester Feagin, May 1986

 

Presented at the EICF Conference

 

This paper briefly reviews the U. S. patent literature on refractory metal casting, with particular reference to titanium. This paper also describes the preliminary work of the author in the casting of Ti6Al4V alloy into shell molds with casting surfaces having compositions between approximately 100% ZrO2 and 100% Y2O3. It also describes results of casting the same alloy in shell molds embedded in bonded sand and having casting surfaces approximately 100% Y5O, having been formed by various techniques.

P-32 Review of Shell Components

Manuel Guerra, May 1994

 

Presented at Cannon-Muskegon Metallurgical Seminar, May 1994 and September 1994 Investment Casting Institute Meeting

 

The selection of the proper refractories for producing an investment cast, shell-mold many times involves making some compromises. Since the slurries contain an active binder, only a handful of refractories have enough stability to provide useful slurry life. In addition, the properties of the refractory (thermal expansion, refractoriness, etc. ) must be considered, as well as the cost.

 

The major constituents of a shell-mold are the binder and the refractory flour. The other components, which are usually in relatively small quantities, are nonetheless very important. This is so because they can not only influence slurry stability, but also overall shell integrity.

 

A brief review of the components necessary to build a shell can be helpful. The shell can be broken down into five areas:1) binder; 2) refractory; 3) surfactant; 4) antifoam; and 5) polymers. While there are some other additives, their usage is relatively small, and the above five areas will be concentrated on here.

P-31 REMASOLƒ‚® ADBONDƒ‚® BV: A Practical Update

James R. Pyne, June 1994

 

Presented to the E. I. C. F. Conference, Prague

 

The REMASOLƒ‚® ADBONDƒ‚® BV system was introduced to the U. S. market in late 1992. It was developed with the goal of replacing Ethyl Silicate as a binder. Several key objectives were established at the outset of the program. These included:

 

  • be an environmentally acceptable binder
  • be usable with all standard refractories
  • process as rapidly as ethyl silicate bonded shell systems.

 

Initially, REMET’s direction was to look at only ethyl silicate replacement situations. The market opened our eyes to the productivity improvement needs of foundries which were using non-polymer modified Colloidal Silica bonded shell systems. Very simply, the REMASOL ADBOND BV systems offered improvements to foundries regardless of which binder system they were currently using.

 

The purpose of this paper is to provide you with some practical foundry experiences based upon the more than 35 foundries who have already converted to the REMASOL ADBOND BV system so that you can better judge the potential value which it can provide to you in your particular production situation.

P-30 REMASOLƒ‚® ADBONDƒ‚® BV: A Practical Update

Charles H. Matzek, February 1994

 

Presented to Verein Deutscher GieƒƒŸereifachleute (VDG)

 

The REMASOLƒ‚® ADBONDƒ‚® BV system was introduced to the U. S. market in late 1992. It was developed with the goal of replacing Ethyl Silicate as a binder. Several key goals were established at the outset of the program. These include:

 

  • be an environmentally acceptable binder
  • be usable with all standard refractories
  • process as rapidly as ethyl silicate bonded shell systems.

 

Initially, REMET’s direction was to look at only ethyl silicate replacement situations. The market opened our eyes to the productivity improvement needs of foundries which were using non-latex modified Colloidal Silica bonded shell systems. Very simply, the REMASOL ADBOND BV systems offered improvements to foundries regardless of which binder system they were currently using. The purpose of this paper is to provide some practical foundry experiences based upon the more than 30 foundries who have already converted to the REMASOL ADBOND BV system so that you can better judge the potential value which it can provide to you in your particular production situation.

P-29 REMASOLƒ‚® ADBONDƒ‚® BV Binder – An Update

Manuel Guerra,ƒ‚ June 1993

 

Presented at the 8th World Conference on Investment Casting,

 

REMASOLƒ‚® ADBONDƒ‚® BV binder was introduced to the Precision Investment Casting industry in October 1992 as a backup binder. The product has now been used in production and many foundries have discovered that REMASOLƒ‚® ADBONDƒ‚® BV does provide for significantly faster shell processing time versus standard colloidal silica, to the point where it can equal alcohol-based binder systems.

 

This paper is an update to the original paper presented in 1992 at the 40th ICI Conference in Las Vegas, Nevada. Additional information on MOLOCHITEƒ„ refractory with a REMASOLƒ‚® ADBONDƒ‚® BV system, and the effect of diluting the binder percent silica of a REMASOLƒ‚® ADBONDƒ‚® BV system are shown.

P-28 REMASOLƒ‚® ADBONDƒ‚® B and REMASOLƒ‚® ADBONDƒ‚® BV Binders

Manuel Guerra,ƒ‚ October 1992

 

Presented at the 40th Annual Meeting of the Investment Casting Institute,

 

The ethyl silicate bonded shell process is under environmental and cost pressure worldwide. Alternative polymer containing binder systems, which claim to approach the speed of ethyl silicate, require expensive, specially sized fused silica refractories. Frequently, fused silica cannot be used because of shell expansion and other considerations versus the refractory system currently in place.

 

REMASOLƒ‚® ADBONDƒ‚® B and REMASOLƒ‚® ADBONDƒ‚® BV binders allows the investment casting foundry to achieve drying rates comparable to ethyl silicate while using any standard refractory.

P-27 REMASILƒ‚® 60: A Refractory for Casting Parts Under High Thermal Stress Conditions

Charles H. Matzek, June 1988

 

In an effort to meet the needs of their customers and to be more competitive and more profitable, ferrous investment casters are casting larger and thicker sectioned parts and are pouring more metal into each shell due to increased part density on the assembly. All of these can cause temperature build ups which exceed the refractoriness of the shell. Deformation occurs, scrap and rework costs increase and profitability is reduced. The high temperature properties of REMASILƒ‚® 60 and MOLOCHITEƒ„ are compared in both colloidal silica and ethyl silicate bonded systems. Conclusions are drawn and recommendations made regarding a shell system that will allow investment casters to extend their ability to cast larger castings.

P-25 Refractories Used for Investment Casting of High-Temperature Alloys

Manuel Guerra

 

Alumina refractories play a key role in contemporary precision investment casting. As one of the main constituents in shell molds for high-temperature alloys, alumina is favored because of its chemical inertness and high-temperature capability. This chapter summarizes the principal physical and chemical characteristics of alumina in relation to the requirements for its use in both the slurry and stucco components of typical shell molds. Particular attention is given to factors affecting slurry stability and shell strength. Other applications for alumina in investment casting, including crucibles, alloy filters and mold insulating warp are briefly reviewed. The current trend to increasing process temperatures dictated by advances in directional solidification technology, points to expanded use of alumina refractories in the investment casting of high-temperature alloys.

P-20 The Influence of Refractory Particle Size of Slurries and Shells

R. Chester Feagin, October 1977

 

Presented at 25th Annual Meeting of the Investment Casting Institute,

 

Some work carried out in the REMET Corporation laboratory relative to certain projects has produced some data which is related to the general subject of particle size of refractories and to its influence on slurry characteristics and strength of shell molds. This work was not carried out specifically to determine the particular influence of particle size distribution on slurries and shells but provided some interesting information on certain systems.

P-19 Hot Modulus of Rupture Measurements on Some Aluminosilicate Shell Systems

R. Chester Feagin,ƒ‚ June 1980

 

Presented at 28th Annual Meeting of the Investment Casting Institute, October 1980 and at the 5th World Conference on Investment Casting, June 1980

 

For the past three years we have been involved in the evaluation of aluminosilicate refractories in various shell systems. This work involves the preparation of shell test specimens in which the first two coats utilize zircon refractory, which is common practice for many shell systems, and the remainder of the shell being totally aluminosilicate refractory both in the slurry and stuccos. Colloidal silica was the major binder evaluated using a prehydrolyzed hybrid REMET A-1 binder containing 20% SiO2. These shell systems were evaluated for modulus of rupture at room temperature in the unfired state after drying, and after firing to temperatures of 649ƒ‚°C, 927ƒ‚°C and 1093ƒ‚°C and then cooling to room temperature. Thermal expansion measurements were run on three shell systems, and hot modulus of rupture measurements at 1371ƒ‚°C were determined on most of the shell series. Results of the room temperature and hot modulus of rupture measurements and thermal expansions are presented with discussion.

Effect of Dilution on REMASOL® ADBOND® BV Binder

Increasing Cost Performance of this Industry Leading Binder

 

Manuel Guerra, October 1993

Presented at Investment Casting Institute Meeting

 

Since its market introduction in late 1992, REMASOLƒ‚® ADBONDƒ‚® BV binder has successfully replaced both ethyl silicate and other colloidal silica binders in foundries where fast processing times are required. Because of its good green strength, a reduction in autoclave cracking can also be realized.

Due to the variety of use conditions, additional work has been done with REMASOL ADBOND BV binder to determine the effect of dilution with respect to shell properties and improved cost performance. This paper updates that work.

P-9 Colloidal Silica in the Precision Casting Industry

 

Maintaining Performance in your Slurry

 

Glenn W. Schiefelbein, March 1987

 

Colloidal silica is the most popular binder used in the precision casting industry today. It is safe, economical, easy to use and performs well. All of these desirable attributes tend to lull us into a sense of well being when we use colloidal silica. We frequently forget that this workhorse of the industry is sensitive and needs some attention to keep it working at its best. This paper describes colloidal silica, its properties and those things that will affect its performance.

P-5 Casting of Reactive Metals into Ceramic Molds

R. Chester Feagin, October 1984

Presented at the 6th World Conference on Investment Casting

This paper describes the results of casting titanium and other reactive metals into experimental ceramic mold systems under controlled conditions. Photomicrographs of metalographic sections show relative degrees of reactivity. Certain specific mold systems are recommended for further study.

P-4 Casting of Reactive Alloys: An Update of Current Technology

Charles H. Matzek, June, 1997

 

Presented at the Cannon-Muskegon Technology Conference in Conjunction with The Paris Air Show

 

Casting quality is an important issue to all foundries. The quality of the casting is, at best, only as good as that of the wax pattern. Nothing used in the investment casting process stands by itself from the standpoint of affecting the final quality. Every component used in the process ƒ€“ the wax, the pattern cleaner, the face coat binder and refractories, the backup binders and refractories, the metal, the crucibles and transfer ladles ƒ€“ interacts with and is affected by the other components. Process controls or, more often, the lack of proper controls has additional impact on quality. Everything the foundryman does in his selection of process conditions, processing controls and raw material selection is directed towards keeping the quality of the finished casting as high as possible. These issues are especially important to those foundries casting reactive alloys. Reactive alloys add another dimension to the problem because the foundry must now have face coats, cores and crucibles/transfer ladles which will not react with the metal during melting, transfer, pouring and cooling.

Alumina and Zirconia Binders

Alternative Binders for Investment Casting

 

R. Chester Feagin, October 1981

Presented at the 29th Annual Meeting of the Investment Casting Institute, October 1981

 

This paper discusses the chemical properties and bonding characteristics of new commercially available binders of aqueous colloidal alumina monohydrate and zirconium oxide.

Potential applications are indicated together with some physical property data derived from bonded refractory systems.

Shell Cracking

Ceramic Shell & Slurry Characterization

Influence of Slurry Properties on Final Molds

 

Jeffrey Niles

Presented by Albert Bozzo at the 51st Technical Conference & Expo Nov. 2003 in Cleveland, OH

 

This paper will discuss in detail the various properties that can be quantified for a ceramic slurry and how they influence the ceramic shell. The raw materials (colloidal silica, polymer, refractory, wetting agent, antifoam) used to make a slurry play a major role in determining the overall final ceramic shell characteristics. There are many factors like silica type and level, polymer type and level, plate weight, solids loading, viscosity, flour particle size distribution, refractory type, etc that play a role on the final ceramic shell properties. These factors will affect the ceramic shell with respect to strength (green, hot, fired), permeability, creep, thermal conductivity, and thermal expansion.

P-42 Comparison Of Properties Of Zircon/Alumino-Silicate Shells With Water-Based And Ethyl Silicate-Based Binders

Manuel Guerra, Jr. ,ƒ‚ May 1998

 

Presented at the 24th EICF Conference in Rome, Italy

 

Two polymer-enhanced, colloidal silica binders (both large and small particle sols) were compared against an alcohol hybrid binder system. The three binders were used with a Zircon and 60% alumina, alumino-silicate flour blend, with Molochite stucco. All of the systems were tested for:green MOR, hot MOR, fired MOR, high temperature creep, and thermal expansion. The hybrid binder had the highest overall MOR strength, but some of this difference could be due to the processing conditions (50-55% RH), which were somewhat more favorable to an alcohol system. There were only minor differences in the creep and thermal expansion results.

P-20 The Influence of Refractory Particle Size of Slurries and Shells

R. Chester Feagin, October 1977

 

Presented at 25th Annual Meeting of the Investment Casting Institute,

 

Some work carried out in the REMET Corporation laboratory relative to certain projects has produced some data which is related to the general subject of particle size of refractories and to its influence on slurry characteristics and strength of shell molds. This work was not carried out specifically to determine the particular influence of particle size distribution on slurries and shells but provided some interesting information on certain systems.

P-17 Factors Affecting Shell Strength and The Effect of Dry Time on Shell Strength

Manuel Guerra & W. O. Roberts (DuPont), April 1992

 

Presented by Albert T. Bozzo at the 22nd EICF Conference, Paris

 

The factors influencing the flexural strength of ceramic shell molds made of refractory particles bonded with air dried colloidal silica have been identified. The bonding mechanism appears to be completely different for the unfired than for the fired shell mold.

 

Before firing, shell strength was found to be mostly a function of binder silica sol characteristics and to be independent of the chemical composition of the bonded particles. In general, the strength of the unfired shell is a function of the

 

  • amount of binder silica in the slurry
  • alkali content of the binder silica sol
  • surface area of the bonded particles.

 

After firing, the strength of the shell was found to be highly dependent on the refractoriness of the bonded particles and the binder solids. In general, the strength of the fired shell is a function of firing time and temperature

 

  • firing time and temperature
  • refractoriness of the bonded particles
  • sodium content of the binder sol
  • gelation concentration of the binder sol

 

In addition, this paper looks at the effects of drying on shell modules of rupture strength. Dry time between dips was varied, and two different final dry times were also evaluated. MOR strips were chosen as the test configuration, and results showed that the amount of dry time between dips can have a significant impact on MOR strength. A longer final dry did not make up for insufficient bonding caused by very short dry times between dips. Because one particular set of drying parameters was chosen for this study, the numbers in this report should not be regarded as absolute. However, for actual production, the results reported here should give foundrymen some idea as to how much strength is lost by insufficient drying.

P-13 The Effect of Dry Time on Shell Strength

Manuel Guerra, October 1991

 

Presented at AFS Meeting

 

This paper looks at the effects of drying on shell modulus of rupture strength. Dry time between dips was varied and two different final dry times were also evaluated. MOR strips were chosen as the test configuration and results showed that the amount of dry time between dips can have a significant impact on MOR strength. A longer final dry did not make up for insufficient bonding caused by very short dry times between dips.

 

Because one particular set of drying parameters was chosen for this study, the numbers in this report should not be regarded as absolute. However, for actual production, the results reported here should give foundrymen some idea as to how much strength is lost by insufficient drying.

P-8 Characteristics of Some Aluminosilicates – Colloidal Silica Shell Systems

R. Chester Feagin, June 1978

 

Presented at the 26th Annual Meeting of the Investment Casting Institute, October 1978 and at the EICF Conference, June 1978

 

This paper is a report on some continued work on alumino-silicate shell systems which have been bonded with colloidal silica. The main purpose of this study is to give some various compositional differences in shell systems, using alumino-silicates, the types of which are currently in use today in the U. S. ; also to show the influence of some materials differences, such as small versus large particle colloidal silica, stucco variations, particle size distributions of the slurry refractory, and the addition of fused silica flour to slurries, and their effect on modulus at rupture of test specimens prepared with such slurries. A group of thermal expansion curves on these systems is also included.

Ceramic Shell Production for Controlled Shell Cracking

12 Guidelines to Limit this Defect

 

Glenn W. Schiefelbein, June 1987

 

Shell cracking is the product of stresses applied during the shell building process. Factors that contribute to the stresses are identified. Practical methods to produce maximum green strength of shells are described. These include the process control of slurries and stucco, mechanics of shell building and drying. Twelve guidelines are given to ensure optimum shell strength to resist stresses that cause cracking.

Avoid Shell Cracking by Controlling Your Process

Reduce Likelihood of this Defect in Dewax

 

Craig T. Lanham, March 1995

 

A discussion focused on shell formulation, control and process to prevent stress on the ceramic shell, which can cause shell cracking.

Raw Materials

Strategies to Manage Zircon Usage in Times of Market Upheaval

Alternative Materials & Strategies to Reduce the Investment Casting Industry’s Reliance on Zircon

 

Manuel Guerra Jr., Frank Tistle, and John Siedlecki

Presented by Frank Tistle at the 58th ICI Technical Conference and Equipment Expo, October 2011. Cincinnati, OH

 

Since mid-2010, the zircon market has experienced another volatile periods of supply and demand leading to price spikes and material allocations, making it difficult for foundries to accurately plan production and price castings. Foundries are re-evaluating their processes with a goal of reducing or eliminating zircon usage to minimize or eliminate their exposure to this volatile market. This paper will discuss testing performed on different refractory materials and binder systems to identify viable and economical zircon sand and flour substitutes.

Reducing Zircon Sand Usage

REMASIL® 60 RG 100 A Replacement Refractory for Zircon

 

Manuel Guerra, Jr.

Presented at the Investment Casting Institute 54th Technical Conference & Expo 2006

 

Abstract: A new material, which has the potential to replace zircon sand for secondary prime dips, and possibly the first prime for some casters, has been developed. REMASILƒ‚® 60 RG100, based on a 60% alumina, alumino-silicate material, is a high Mullite product which has been fired to a high temperature. It is then sized to provide the optimum match to zircon sand (the distribution is slightly coarser than zircon. ) Laboratory testing (MOR, permeability and thermal expansion) was performed to determine how closely the RG100 sand performed versus zircon. The test results revealed some small differences between the two sands. The method of application (fluid bed or rainfall sander) resulted in only minor differences in the permeability or MOR results.

P-41 The Effect of Particle Size of Fused Silica Flour on Shell Properties

Jeffrey C. Niles, September 1997

 

Presented at the ICI 45th Annual Technical Meeting, Atlanta GA, September, 1997

 

This study evaluated the effect that particle size of fused silica flour has on shell properties. Three different flour sizings were tested (-120, -200 and ƒ€“270 mesh sizings) with REMASOL SP-30 colloidal silica (diluted to 26% silica solids) and both fused silica stucco (30 x 50 mesh) and aluminosilicate stucco (20 x 40 mesh). The test results include green, hot and fired MOR, hot permeability, thermal expansion and high temperature creep.

P-38 Cobalt Aluminate Levels in Primary Slurries

Manuel Guerra and Jeffrey C. Niles, October 1996

 

Presented at the Investment Casting Institute/World Conference, San Francisco, October 1996 by Manuel Guerra

 

Cobalt aluminate from Shepherd Color Company was evaluated for its effectiveness as an inoculant for investment cast alloys. Various levels of cobalt content (of the cobalt aluminate) and percent cobalt aluminate in the primary slurry were tested. The results are presented in this paper.

P-37 Water Quality and Colloidal Silica Slurries

Craig T. Lanham, August 1992

 

As the foundrymanƒ€™s interest in reducing manufacturing costs through improved shellroom process control has increased the subject of water quality has become increasingly important. All too often there are unanswered questions about the level of water quality needed to properly make and control water based shellroom slurries. Once water quality is defined the foundry is then confronted with the question of how to meet this need in the most convenient and cost effective way.

 

No water source is completely pure. Every source, whether industrial, commercial, or natural, contains dissolved solids or contaminant salts. These dissolved solids conduct electricity. This conductivity allows us to measure the concentration of these contaminants. The measurement, in parts per million, is referred to as a measurement of Total Dissolved Solids (TDS) and is measured by Specific Conductance in Micromhos or Specific Resistance in Ohms.

 

There are three major water treatment processes in use today to produce high purity water; Distillation, Reverse Osmosis and Deionization. Depending on the water volume and the level of quality required these systems may be used separately or in conjunction with each other.

P-36 Using Stucco More Effectively

Charles H. Matzek, February 1988

 

Modern Casting

 

A proper stucco program is essential in order to successfully make a shell which will yield a high quality investment casting. The stucco program involves the choice of the proper stucco size for each coat, using stucco materials which have a tightly controlled particle size distribution and proper maintenance of the stucco application equipment.

P-34 Titanium Investment Casting

R. Chester Feagin, May 1986

 

Presented at the EICF Conference

 

This paper briefly reviews the U. S. patent literature on refractory metal casting, with particular reference to titanium. This paper also describes the preliminary work of the author in the casting of Ti6Al4V alloy into shell molds with casting surfaces having compositions between approximately 100% ZrO2 and 100% Y2O3. It also describes results of casting the same alloy in shell molds embedded in bonded sand and having casting surfaces approximately 100% Y5O, having been formed by various techniques.

P-33 Surfactants, Wetting and Foams

Albert T. Bozzo, September 1989

 

Wetting agents have traditionally been added to aqueous based prime slurries to help wet out the refractory flours and to enable the slurry to wet the wax patterns. Antifoams are only necessary to negate the foaming effect of the wetting agent. The minimum effective concentration of wetting agent and antifoam is considered the best (do not overtreat).

 

The current generation of latex modified binders, special new wax formulations and restrictions on pattern cleaning compounds puts added pressure on the proper selection of a wetting agent and antifoam.

 

What are these products you have been working with? How effective are they for their intended use? Do they promote stability in the slurry system? This paper is a guide to your better understanding of the products available to the PIC foundry.

P-32 Review of Shell Components

Manuel Guerra, May 1994

 

Presented at Cannon-Muskegon Metallurgical Seminar, May 1994 and September 1994 Investment Casting Institute Meeting

 

The selection of the proper refractories for producing an investment cast, shell-mold many times involves making some compromises. Since the slurries contain an active binder, only a handful of refractories have enough stability to provide useful slurry life. In addition, the properties of the refractory (thermal expansion, refractoriness, etc. ) must be considered, as well as the cost.

 

The major constituents of a shell-mold are the binder and the refractory flour. The other components, which are usually in relatively small quantities, are nonetheless very important. This is so because they can not only influence slurry stability, but also overall shell integrity.

 

A brief review of the components necessary to build a shell can be helpful. The shell can be broken down into five areas:1) binder; 2) refractory; 3) surfactant; 4) antifoam; and 5) polymers. While there are some other additives, their usage is relatively small, and the above five areas will be concentrated on here.

P-27 REMASILƒ‚® 60: A Refractory for Casting Parts Under High Thermal Stress Conditions

Charles H. Matzek, June 1988

 

In an effort to meet the needs of their customers and to be more competitive and more profitable, ferrous investment casters are casting larger and thicker sectioned parts and are pouring more metal into each shell due to increased part density on the assembly. All of these can cause temperature build ups which exceed the refractoriness of the shell. Deformation occurs, scrap and rework costs increase and profitability is reduced. The high temperature properties of REMASILƒ‚® 60 and MOLOCHITEƒ„ are compared in both colloidal silica and ethyl silicate bonded systems. Conclusions are drawn and recommendations made regarding a shell system that will allow investment casters to extend their ability to cast larger castings.

P-23 Particle Size Determination of Refractories

R. Chester Feagin, October 1977

 

Presented at 25th Annual Meeting of the Investment Casting Institute,

 

Every investment caster is concerned with particle size distribution of refractories. Particles of various types of material are used in slurries, stuccos, finishing materials, abrasives, and even binders, etc. , yet many casters have very little idea of the best means for measuring particle size and relatively few do any control testing on refractory materials. The purpose of this discussion, therefore, is to review a few of the recommended methods for particle size determination for refractories and similar materials along with some of the pros and cons of each method. This discussion will not review methods for particle size of silica in colloidal silica.

P-11 Dipcoat Nucleation

R. Chester Feagin, 1967

 

This paper will give a brief summary of the generally accepted principles of nucleation, along with a brief review of the technical and patent literature relating to dipcoat nucleation. In addition, a description will be given of various experiments that have been carried out employing different nucleating agents. Several specific examples of grain size controlled castings produced in molds having nucleants on the mold surface will be shown as described.

P-8 Characteristics of Some Aluminosilicates – Colloidal Silica Shell Systems

R. Chester Feagin, June 1978

 

Presented at the 26th Annual Meeting of the Investment Casting Institute, October 1978 and at the EICF Conference, June 1978

 

This paper is a report on some continued work on alumino-silicate shell systems which have been bonded with colloidal silica. The main purpose of this study is to give some various compositional differences in shell systems, using alumino-silicates, the types of which are currently in use today in the U. S. ; also to show the influence of some materials differences, such as small versus large particle colloidal silica, stucco variations, particle size distributions of the slurry refractory, and the addition of fused silica flour to slurries, and their effect on modulus at rupture of test specimens prepared with such slurries. A group of thermal expansion curves on these systems is also included.

Alumina and Zirconia Binders

Alternative Binders for Investment Casting

 

R. Chester Feagin, October 1981

Presented at the 29th Annual Meeting of the Investment Casting Institute, October 1981

 

This paper discusses the chemical properties and bonding characteristics of new commercially available binders of aqueous colloidal alumina monohydrate and zirconium oxide.

Potential applications are indicated together with some physical property data derived from bonded refractory systems.

P-1A Study of the Consistency of Zircon Flour

Manuel Guerra, July 1991

 

Proper control of slurries used in investment casting is critical in producing a high quality finished part. The flour component is by far the largest part (by weight) of the slurry, yet its effect on rheology and overall life is one of the least understood aspects in slurry control. It is well known that the type of flour used and its particle size distribution greatly affect the resulting slurry viscosity and coating properties. This is especially important on the prime layer.

 

Zircon flour, a naturally occurring mineral, is one of the most commonly used flours for prime slurries. It combines the desirable characteristics of high refractoriness, good chemical inertness, and relatively high abundance. Yet, when the investment caster receives his zircon flour, he is at the mercy of the supplying company’s ability to produce a consistent grind. Can a consistent product be produced without the added expense of blending? The answer appears to be a conditional yes.

Adbond Binder System

Ceramic Shell Drying | Investment Casting Defects | Remet

Reducing Delays Effecting Productivity, Scrap & Rework

 

Manuel Guerra,

Presented at the ICI 57th Technical Conference & Expo 2010

 

The drying of recessed areas can contribute to significant time delays in the processing of shell molds, as well as leading to rework and scrap issues. This paper will present data from various testing to evaluate the effect of different binders (polymer and non-polymer) to try to overcome this all too common problem.

REMASOL® ADBOND® SP-3301 and LP-3301 Binders

A Faster Setting Investment Casting Binder

 

Albert Bozo

ICI 48th Annual Technical Meeting 2000.

 

Remasolƒ‚® ADBONDƒ‚® SP-3301 and LP-3301 are enhancements of the commercially successful Remasol ADBOND BV binders to promote faster setting shell systems. These systems are particularly viable where parts contain deep pockets that are difficult to dry. Because it can be used at low silica concentrations, it has potential in aluminum casting.

The Effect of Polymer Selection and Level on Shell Properties

Use & Effects on Shell Strength, Permeability & Rheology

 

Jeffrey Niles and Albert Bozoƒ‚

ICI 49th Annual Technical Meeting 2001.

 

A significant number of investment casting foundries add organic polymers to their backup slurry systems to make process improvements. These improvements can be in added green strength or permeability, better rheology, and thicker shells, etc. This paper will look at the relationship between polymer selection, use level, and viscosity to previously mentioned properties. The individual foundry can then use these results to optimize the polymer type, level and viscosity for their specific needs.

P-42 Comparison Of Properties Of Zircon/Alumino-Silicate Shells With Water-Based And Ethyl Silicate-Based Binders

Manuel Guerra, Jr. ,ƒ‚ May 1998

 

Presented at the 24th EICF Conference in Rome, Italy

 

Two polymer-enhanced, colloidal silica binders (both large and small particle sols) were compared against an alcohol hybrid binder system. The three binders were used with a Zircon and 60% alumina, alumino-silicate flour blend, with Molochite stucco. All of the systems were tested for:green MOR, hot MOR, fired MOR, high temperature creep, and thermal expansion. The hybrid binder had the highest overall MOR strength, but some of this difference could be due to the processing conditions (50-55% RH), which were somewhat more favorable to an alcohol system. There were only minor differences in the creep and thermal expansion results.

P-31 REMASOLƒ‚® ADBONDƒ‚® BV: A Practical Update

James R. Pyne, June 1994

 

Presented to the E. I. C. F. Conference, Prague

 

The REMASOLƒ‚® ADBONDƒ‚® BV system was introduced to the U. S. market in late 1992. It was developed with the goal of replacing Ethyl Silicate as a binder. Several key objectives were established at the outset of the program. These included:

 

  • be an environmentally acceptable binder
  • be usable with all standard refractories
  • process as rapidly as ethyl silicate bonded shell systems.

 

Initially, REMET’s direction was to look at only ethyl silicate replacement situations. The market opened our eyes to the productivity improvement needs of foundries which were using non-polymer modified Colloidal Silica bonded shell systems. Very simply, the REMASOL ADBOND BV systems offered improvements to foundries regardless of which binder system they were currently using.

 

The purpose of this paper is to provide you with some practical foundry experiences based upon the more than 35 foundries who have already converted to the REMASOL ADBOND BV system so that you can better judge the potential value which it can provide to you in your particular production situation.

P-30 REMASOLƒ‚® ADBONDƒ‚® BV: A Practical Update

Charles H. Matzek, February 1994

 

Presented to Verein Deutscher GieƒƒŸereifachleute (VDG)

 

The REMASOLƒ‚® ADBONDƒ‚® BV system was introduced to the U. S. market in late 1992. It was developed with the goal of replacing Ethyl Silicate as a binder. Several key goals were established at the outset of the program. These include:

 

  • be an environmentally acceptable binder
  • be usable with all standard refractories
  • process as rapidly as ethyl silicate bonded shell systems.

 

Initially, REMET’s direction was to look at only ethyl silicate replacement situations. The market opened our eyes to the productivity improvement needs of foundries which were using non-latex modified Colloidal Silica bonded shell systems. Very simply, the REMASOL ADBOND BV systems offered improvements to foundries regardless of which binder system they were currently using. The purpose of this paper is to provide some practical foundry experiences based upon the more than 30 foundries who have already converted to the REMASOL ADBOND BV system so that you can better judge the potential value which it can provide to you in your particular production situation.

P-29 REMASOLƒ‚® ADBONDƒ‚® BV Binder – An Update

Manuel Guerra,ƒ‚ June 1993

 

Presented at the 8th World Conference on Investment Casting,

 

REMASOLƒ‚® ADBONDƒ‚® BV binder was introduced to the Precision Investment Casting industry in October 1992 as a backup binder. The product has now been used in production and many foundries have discovered that REMASOLƒ‚® ADBONDƒ‚® BV does provide for significantly faster shell processing time versus standard colloidal silica, to the point where it can equal alcohol-based binder systems.

 

This paper is an update to the original paper presented in 1992 at the 40th ICI Conference in Las Vegas, Nevada. Additional information on MOLOCHITEƒ„ refractory with a REMASOLƒ‚® ADBONDƒ‚® BV system, and the effect of diluting the binder percent silica of a REMASOLƒ‚® ADBONDƒ‚® BV system are shown.

P-28 REMASOLƒ‚® ADBONDƒ‚® B and REMASOLƒ‚® ADBONDƒ‚® BV Binders

Manuel Guerra,ƒ‚ October 1992

 

Presented at the 40th Annual Meeting of the Investment Casting Institute,

 

The ethyl silicate bonded shell process is under environmental and cost pressure worldwide. Alternative polymer containing binder systems, which claim to approach the speed of ethyl silicate, require expensive, specially sized fused silica refractories. Frequently, fused silica cannot be used because of shell expansion and other considerations versus the refractory system currently in place.

 

REMASOLƒ‚® ADBONDƒ‚® B and REMASOLƒ‚® ADBONDƒ‚® BV binders allows the investment casting foundry to achieve drying rates comparable to ethyl silicate while using any standard refractory.

Enhanced Binder Systems for the Investment Casting Industry

Material Additions to Improve Performance of Colloidal Silica for Investment Casting

 

Jeffrey C. Niles, March 1995

 

The development of enhanced binder systems has been an ongoing process which has been accelerated with increasingly restrictive limits on alcohol emissions. Ethyl silicate based ceramic shell systems were ideal because of their fast processing capabilities and resulting strength. The bonds in an ethyl silicate system could be chemically set with ammonia and the alcohol would evaporate rapidly because of its relatively high vapor pressure. Work has been done on chemically setting water based systems, but the results have been poor, with low strength compared to alcohol systems. The direction is now to modify existing colloidal silica binders to allow them to produce similar processing times and strengths as ethyl silicate binders. These types of binders have been termed “enhanced binders”.

The first enhanced binder systems were developed for primary applications. The primary binder has different requirements versus the backup. It should have longer term stability because of its slower turnover rate and should provide excellent coating characteristics. The goal of an enhanced primary binder is to reduce surface defects such as buckle, cracking and lifting and promote adhesion to the wax pattern.

Various types of materials such as latexes, polyvinyl alcohols, methylcellulose, acrylic resins, etc. , have been evaluated in colloidal silica to develop enhanced primary and backup binders. The results of this work have been varied because of the wide number of materials that must be evaluated and incomplete understanding of the process. In the last 8 to 10 years, a great deal of work has been done by various companies to produce significant advances in enhanced binder systems. These new generation products, such as REMASOLƒ‚® ADBONDƒ‚® BV and LUDOXƒ‚® SK have opened the door for even more research into these binder types. In the last five years, many enhanced binder products have been introduced. The enhanced primary binders have been shown to reduce typical primary type drying defects, while the backup binders have provided faster processing and higher strengths versus standard colloidal silicas.

Effect of Dilution on REMASOL® ADBOND® BV Binder

Increasing Cost Performance of this Industry Leading Binder

 

Manuel Guerra, October 1993

Presented at Investment Casting Institute Meeting

 

Since its market introduction in late 1992, REMASOLƒ‚® ADBONDƒ‚® BV binder has successfully replaced both ethyl silicate and other colloidal silica binders in foundries where fast processing times are required. Because of its good green strength, a reduction in autoclave cracking can also be realized.

Due to the variety of use conditions, additional work has been done with REMASOL ADBOND BV binder to determine the effect of dilution with respect to shell properties and improved cost performance. This paper updates that work.

Enhanced Binder System

Ceramic Shell Drying | Investment Casting Defects | Remet

Reducing Delays Effecting Productivity, Scrap & Rework

 

Manuel Guerra,

Presented at the ICI 57th Technical Conference & Expo 2010

 

The drying of recessed areas can contribute to significant time delays in the processing of shell molds, as well as leading to rework and scrap issues. This paper will present data from various testing to evaluate the effect of different binders (polymer and non-polymer) to try to overcome this all too common problem.

P-42 Comparison Of Properties Of Zircon/Alumino-Silicate Shells With Water-Based And Ethyl Silicate-Based Binders

Manuel Guerra, Jr. ,ƒ‚ May 1998

 

Presented at the 24th EICF Conference in Rome, Italy

 

Two polymer-enhanced, colloidal silica binders (both large and small particle sols) were compared against an alcohol hybrid binder system. The three binders were used with a Zircon and 60% alumina, alumino-silicate flour blend, with Molochite stucco. All of the systems were tested for:green MOR, hot MOR, fired MOR, high temperature creep, and thermal expansion. The hybrid binder had the highest overall MOR strength, but some of this difference could be due to the processing conditions (50-55% RH), which were somewhat more favorable to an alcohol system. There were only minor differences in the creep and thermal expansion results.

P-31 REMASOLƒ‚® ADBONDƒ‚® BV: A Practical Update

James R. Pyne, June 1994

 

Presented to the E. I. C. F. Conference, Prague

 

The REMASOLƒ‚® ADBONDƒ‚® BV system was introduced to the U. S. market in late 1992. It was developed with the goal of replacing Ethyl Silicate as a binder. Several key objectives were established at the outset of the program. These included:

 

  • be an environmentally acceptable binder
  • be usable with all standard refractories
  • process as rapidly as ethyl silicate bonded shell systems.

 

Initially, REMET’s direction was to look at only ethyl silicate replacement situations. The market opened our eyes to the productivity improvement needs of foundries which were using non-polymer modified Colloidal Silica bonded shell systems. Very simply, the REMASOL ADBOND BV systems offered improvements to foundries regardless of which binder system they were currently using.

 

The purpose of this paper is to provide you with some practical foundry experiences based upon the more than 35 foundries who have already converted to the REMASOL ADBOND BV system so that you can better judge the potential value which it can provide to you in your particular production situation.

P-30 REMASOLƒ‚® ADBONDƒ‚® BV: A Practical Update

Charles H. Matzek, February 1994

 

Presented to Verein Deutscher GieƒƒŸereifachleute (VDG)

 

The REMASOLƒ‚® ADBONDƒ‚® BV system was introduced to the U. S. market in late 1992. It was developed with the goal of replacing Ethyl Silicate as a binder. Several key goals were established at the outset of the program. These include:

 

  • be an environmentally acceptable binder
  • be usable with all standard refractories
  • process as rapidly as ethyl silicate bonded shell systems.

 

Initially, REMET’s direction was to look at only ethyl silicate replacement situations. The market opened our eyes to the productivity improvement needs of foundries which were using non-latex modified Colloidal Silica bonded shell systems. Very simply, the REMASOL ADBOND BV systems offered improvements to foundries regardless of which binder system they were currently using. The purpose of this paper is to provide some practical foundry experiences based upon the more than 30 foundries who have already converted to the REMASOL ADBOND BV system so that you can better judge the potential value which it can provide to you in your particular production situation.

P-29 REMASOLƒ‚® ADBONDƒ‚® BV Binder – An Update

Manuel Guerra,ƒ‚ June 1993

 

Presented at the 8th World Conference on Investment Casting,

 

REMASOLƒ‚® ADBONDƒ‚® BV binder was introduced to the Precision Investment Casting industry in October 1992 as a backup binder. The product has now been used in production and many foundries have discovered that REMASOLƒ‚® ADBONDƒ‚® BV does provide for significantly faster shell processing time versus standard colloidal silica, to the point where it can equal alcohol-based binder systems.

 

This paper is an update to the original paper presented in 1992 at the 40th ICI Conference in Las Vegas, Nevada. Additional information on MOLOCHITEƒ„ refractory with a REMASOLƒ‚® ADBONDƒ‚® BV system, and the effect of diluting the binder percent silica of a REMASOLƒ‚® ADBONDƒ‚® BV system are shown.

P-28 REMASOLƒ‚® ADBONDƒ‚® B and REMASOLƒ‚® ADBONDƒ‚® BV Binders

Manuel Guerra,ƒ‚ October 1992

 

Presented at the 40th Annual Meeting of the Investment Casting Institute,

 

The ethyl silicate bonded shell process is under environmental and cost pressure worldwide. Alternative polymer containing binder systems, which claim to approach the speed of ethyl silicate, require expensive, specially sized fused silica refractories. Frequently, fused silica cannot be used because of shell expansion and other considerations versus the refractory system currently in place.

 

REMASOLƒ‚® ADBONDƒ‚® B and REMASOLƒ‚® ADBONDƒ‚® BV binders allows the investment casting foundry to achieve drying rates comparable to ethyl silicate while using any standard refractory.

P-15 Enhanced Binders for the Production of Ceramic Shells

Craig T. Lanham, November 1994

 

The limits of any foundryƒ€™s casting capabilities are governed by the ceramic mold it produces. These constraints effect both casting quality and foundry responsiveness. As in the past, current and future binder developments will continue to define and constrain how the demands of casting buyers are met.

 

The ceramic shell process and the binders the Investment Caster use are relatively young, only 50 to 60 years old. The desire and need to pour high temperature ferrous alloys led to the development of ethyl silicate binders in the mid 1930ƒ€™s. Colloidal silica was introduced as a binder in ceramic molds a decade later. During the mid to late 1940ƒ€™s the industry began to move away from the solid mold process to improve casting surfaces. By the mid 1950ƒ€™s the development of the ceramic shell process was well underway.

 

As most in our industry know, environmental concerns and ever increasing material costs are inducing foundries to convert from ethyl silicate binders to colloidal silica binders. As we move away from the alcohol based binders we have had to deal with the traditional problems associated with the use of water based binders; high viscosity slurries that wet poorly, process slowly, and produce lower green strength shells.

Enhanced Binder Systems for the Investment Casting Industry

Material Additions to Improve Performance of Colloidal Silica for Investment Casting

 

Jeffrey C. Niles, March 1995

 

The development of enhanced binder systems has been an ongoing process which has been accelerated with increasingly restrictive limits on alcohol emissions. Ethyl silicate based ceramic shell systems were ideal because of their fast processing capabilities and resulting strength. The bonds in an ethyl silicate system could be chemically set with ammonia and the alcohol would evaporate rapidly because of its relatively high vapor pressure. Work has been done on chemically setting water based systems, but the results have been poor, with low strength compared to alcohol systems. The direction is now to modify existing colloidal silica binders to allow them to produce similar processing times and strengths as ethyl silicate binders. These types of binders have been termed “enhanced binders”.

The first enhanced binder systems were developed for primary applications. The primary binder has different requirements versus the backup. It should have longer term stability because of its slower turnover rate and should provide excellent coating characteristics. The goal of an enhanced primary binder is to reduce surface defects such as buckle, cracking and lifting and promote adhesion to the wax pattern.

Various types of materials such as latexes, polyvinyl alcohols, methylcellulose, acrylic resins, etc. , have been evaluated in colloidal silica to develop enhanced primary and backup binders. The results of this work have been varied because of the wide number of materials that must be evaluated and incomplete understanding of the process. In the last 8 to 10 years, a great deal of work has been done by various companies to produce significant advances in enhanced binder systems. These new generation products, such as REMASOLƒ‚® ADBONDƒ‚® BV and LUDOXƒ‚® SK have opened the door for even more research into these binder types. In the last five years, many enhanced binder products have been introduced. The enhanced primary binders have been shown to reduce typical primary type drying defects, while the backup binders have provided faster processing and higher strengths versus standard colloidal silicas.

Effect of Dilution on REMASOL® ADBOND® BV Binder

Increasing Cost Performance of this Industry Leading Binder

 

Manuel Guerra, October 1993

Presented at Investment Casting Institute Meeting

 

Since its market introduction in late 1992, REMASOLƒ‚® ADBONDƒ‚® BV binder has successfully replaced both ethyl silicate and other colloidal silica binders in foundries where fast processing times are required. Because of its good green strength, a reduction in autoclave cracking can also be realized.

Due to the variety of use conditions, additional work has been done with REMASOL ADBOND BV binder to determine the effect of dilution with respect to shell properties and improved cost performance. This paper updates that work.

History of Investment Casting

P-21 Investment Casting 1930-1950

R. Chester Feagin, September 1991

 

Presented at 39th Annual Meeting of the Investment Casting Institute,

 

This paper will describe the early beginnings of commercial investment casting in the United States at Austenal Company where the first turbine bucket for airplane superchargers was cast. A summary of the processes used and a list of the main casters are noted. A list is given of the patents issued at that time and a description of the principal ones, some of which are still in use today.

Process Control

P-48 The Effect of Slurry Viscosity and Stucco Size on Shell Properties

Manuel Guerra,

 

Presented by Charles H. Matzek at the World Conference, Monte Carlo in 2000

 

Viscosity is one method used by foundries to control their slurries and,ultimately, the characteristics of their shells. In this paper, the relationship between slurry viscosity and shell properties such as strength, thickness and permeability is explored.

 

A series of experiments was undertaken to establish the effect of backup slurry viscosity on these key shell characteristics. Test shells were made using a common primary coat and four backup slurries of varying viscosity. Viscosities were measured and controlled using the Zahn flow cups commonly used in the investment casting industry. In addition, the effect of stucco particle size on shell thickness was investigated by using three different stucco grades to build the test specimens.

 

Each set of shells were tested using industry standard methods to evaluate the effect of backup slurry viscosity and stucco size on green, hot and as-fired properties. Numeric and graphical results from the experiments are presented. The conclusions drawn will help the investment caster understand the complex interactions involved during shell build as well as indicating how systems can be modified to optimize shell properties.

P-42 Comparison Of Properties Of Zircon/Alumino-Silicate Shells With Water-Based And Ethyl Silicate-Based Binders

Manuel Guerra, Jr. ,ƒ‚ May 1998

 

Presented at the 24th EICF Conference in Rome, Italy

 

Two polymer-enhanced, colloidal silica binders (both large and small particle sols) were compared against an alcohol hybrid binder system. The three binders were used with a Zircon and 60% alumina, alumino-silicate flour blend, with Molochite stucco. All of the systems were tested for:green MOR, hot MOR, fired MOR, high temperature creep, and thermal expansion. The hybrid binder had the highest overall MOR strength, but some of this difference could be due to the processing conditions (50-55% RH), which were somewhat more favorable to an alcohol system. There were only minor differences in the creep and thermal expansion results.

P-41 The Effect of Particle Size of Fused Silica Flour on Shell Properties

Jeffrey C. Niles, September 1997

 

Presented at the ICI 45th Annual Technical Meeting, Atlanta GA, September, 1997

 

This study evaluated the effect that particle size of fused silica flour has on shell properties. Three different flour sizings were tested (-120, -200 and ƒ€“270 mesh sizings) with REMASOL SP-30 colloidal silica (diluted to 26% silica solids) and both fused silica stucco (30 x 50 mesh) and aluminosilicate stucco (20 x 40 mesh). The test results include green, hot and fired MOR, hot permeability, thermal expansion and high temperature creep.

P-40 Slurry Development and Control

Julian G. Kovacs, August 1997

 

Most foundries’ success is dependent on the foundry men’s intelligent choice of materials to their shell development and on the particular control of the variables in the process that they have established in their operation.

 

This paper attempts to provide some guidelines to the foundry men about the material selection available for making reliable slurries and to assist them in setting up control parameters for the slurry process. Some practical suggestions about mixing slurries and drying shells will also be included.

 

The selection of binders, refractories and other components of slurries will be discussed. Slurry preparation, mixing, maintenance and testing will also be reviewed.

P-37 Water Quality and Colloidal Silica Slurries

Craig T. Lanham, August 1992

 

As the foundrymanƒ€™s interest in reducing manufacturing costs through improved shellroom process control has increased the subject of water quality has become increasingly important. All too often there are unanswered questions about the level of water quality needed to properly make and control water based shellroom slurries. Once water quality is defined the foundry is then confronted with the question of how to meet this need in the most convenient and cost effective way.

 

No water source is completely pure. Every source, whether industrial, commercial, or natural, contains dissolved solids or contaminant salts. These dissolved solids conduct electricity. This conductivity allows us to measure the concentration of these contaminants. The measurement, in parts per million, is referred to as a measurement of Total Dissolved Solids (TDS) and is measured by Specific Conductance in Micromhos or Specific Resistance in Ohms.

 

There are three major water treatment processes in use today to produce high purity water; Distillation, Reverse Osmosis and Deionization. Depending on the water volume and the level of quality required these systems may be used separately or in conjunction with each other.

P-36 Using Stucco More Effectively

Charles H. Matzek, February 1988

 

Modern Casting

 

A proper stucco program is essential in order to successfully make a shell which will yield a high quality investment casting. The stucco program involves the choice of the proper stucco size for each coat, using stucco materials which have a tightly controlled particle size distribution and proper maintenance of the stucco application equipment.

P-35 Understanding the Shell Room Process

Craig T. Lanham, November 1994

 

Producers of metal products, whether cast, fabricated, forged, or machined, spend more time than they would like analyzing the cause of defects in their products. The characterization of these defects is considered to be a critical step in lowering scrap rates and improving practices, processes, and the foundryƒ€™s bottom line.

 

A discussion of pattern production and preparation, shell room production environments, shell room process control, and offers suggestions, recommendations and references.

P-24 Proper Techniques to be Followed in Preparing and Maintaining a Slurry

Theodore R. Owens, June 1987

 

An overview of slurry mixing procedures, wetting agents and antifoams, slurry maintenance procedures, and quality control checks.

P-22 MOR, Who Needs It?

Craig T. Lanham, October 1993

 

Do we really need MOR testing? Under continual pressure to reduce overhead costs this is a typical question at most foundries. ased on a traditional understanding of Modulus of Rupture or MOR testing and past evaluation techniques, I think the question is justified. In order to find value in MOR testing, todayƒ€™s foundryman needs to advance his understanding of this test. This paper will describe proper MOR testing and offer a new perspective on the uses for this valuable investigative tool. Perhaps you will then be able to answer the question; ƒ€œMOR, Who Needs It?ƒ€

 

 

P-20 The Influence of Refractory Particle Size of Slurries and Shells

R. Chester Feagin, October 1977

 

Presented at 25th Annual Meeting of the Investment Casting Institute,

 

Some work carried out in the REMET Corporation laboratory relative to certain projects has produced some data which is related to the general subject of particle size of refractories and to its influence on slurry characteristics and strength of shell molds. This work was not carried out specifically to determine the particular influence of particle size distribution on slurries and shells but provided some interesting information on certain systems.

P-18 Factors Effecting Slurry Rheology

Glenn W. Schiefelbein & Manuel Guerra, February 1991

 

Today foundrymen are interested in controlling casting quality. This includes the control of surface finish, internal shrink and metal grain size. Shell and metal controls work synergistically to create conditions that produce a quality product on a consistent basis. This paper will address factors that effect shell uniformity, namely slurry control.

P-17 Factors Affecting Shell Strength and The Effect of Dry Time on Shell Strength

Manuel Guerra & W. O. Roberts (DuPont), April 1992

 

Presented by Albert T. Bozzo at the 22nd EICF Conference, Paris

 

The factors influencing the flexural strength of ceramic shell molds made of refractory particles bonded with air dried colloidal silica have been identified. The bonding mechanism appears to be completely different for the unfired than for the fired shell mold.

 

Before firing, shell strength was found to be mostly a function of binder silica sol characteristics and to be independent of the chemical composition of the bonded particles. In general, the strength of the unfired shell is a function of the

 

  • amount of binder silica in the slurry
  • alkali content of the binder silica sol
  • surface area of the bonded particles.

 

After firing, the strength of the shell was found to be highly dependent on the refractoriness of the bonded particles and the binder solids. In general, the strength of the fired shell is a function of firing time and temperature

 

  • firing time and temperature
  • refractoriness of the bonded particles
  • sodium content of the binder sol
  • gelation concentration of the binder sol

 

In addition, this paper looks at the effects of drying on shell modules of rupture strength. Dry time between dips was varied, and two different final dry times were also evaluated. MOR strips were chosen as the test configuration, and results showed that the amount of dry time between dips can have a significant impact on MOR strength. A longer final dry did not make up for insufficient bonding caused by very short dry times between dips. Because one particular set of drying parameters was chosen for this study, the numbers in this report should not be regarded as absolute. However, for actual production, the results reported here should give foundrymen some idea as to how much strength is lost by insufficient drying.

P-15 Enhanced Binders for the Production of Ceramic Shells

Craig T. Lanham, November 1994

 

The limits of any foundryƒ€™s casting capabilities are governed by the ceramic mold it produces. These constraints effect both casting quality and foundry responsiveness. As in the past, current and future binder developments will continue to define and constrain how the demands of casting buyers are met.

 

The ceramic shell process and the binders the Investment Caster use are relatively young, only 50 to 60 years old. The desire and need to pour high temperature ferrous alloys led to the development of ethyl silicate binders in the mid 1930ƒ€™s. Colloidal silica was introduced as a binder in ceramic molds a decade later. During the mid to late 1940ƒ€™s the industry began to move away from the solid mold process to improve casting surfaces. By the mid 1950ƒ€™s the development of the ceramic shell process was well underway.

 

As most in our industry know, environmental concerns and ever increasing material costs are inducing foundries to convert from ethyl silicate binders to colloidal silica binders. As we move away from the alcohol based binders we have had to deal with the traditional problems associated with the use of water based binders; high viscosity slurries that wet poorly, process slowly, and produce lower green strength shells.

Enhanced Binder Systems for the Investment Casting Industry

Material Additions to Improve Performance of Colloidal Silica for Investment Casting

 

Jeffrey C. Niles, March 1995

 

The development of enhanced binder systems has been an ongoing process which has been accelerated with increasingly restrictive limits on alcohol emissions. Ethyl silicate based ceramic shell systems were ideal because of their fast processing capabilities and resulting strength. The bonds in an ethyl silicate system could be chemically set with ammonia and the alcohol would evaporate rapidly because of its relatively high vapor pressure. Work has been done on chemically setting water based systems, but the results have been poor, with low strength compared to alcohol systems. The direction is now to modify existing colloidal silica binders to allow them to produce similar processing times and strengths as ethyl silicate binders. These types of binders have been termed “enhanced binders”.

The first enhanced binder systems were developed for primary applications. The primary binder has different requirements versus the backup. It should have longer term stability because of its slower turnover rate and should provide excellent coating characteristics. The goal of an enhanced primary binder is to reduce surface defects such as buckle, cracking and lifting and promote adhesion to the wax pattern.

Various types of materials such as latexes, polyvinyl alcohols, methylcellulose, acrylic resins, etc. , have been evaluated in colloidal silica to develop enhanced primary and backup binders. The results of this work have been varied because of the wide number of materials that must be evaluated and incomplete understanding of the process. In the last 8 to 10 years, a great deal of work has been done by various companies to produce significant advances in enhanced binder systems. These new generation products, such as REMASOLƒ‚® ADBONDƒ‚® BV and LUDOXƒ‚® SK have opened the door for even more research into these binder types. In the last five years, many enhanced binder products have been introduced. The enhanced primary binders have been shown to reduce typical primary type drying defects, while the backup binders have provided faster processing and higher strengths versus standard colloidal silicas.

P-13 The Effect of Dry Time on Shell Strength

Manuel Guerra, October 1991

 

Presented at AFS Meeting

 

This paper looks at the effects of drying on shell modulus of rupture strength. Dry time between dips was varied and two different final dry times were also evaluated. MOR strips were chosen as the test configuration and results showed that the amount of dry time between dips can have a significant impact on MOR strength. A longer final dry did not make up for insufficient bonding caused by very short dry times between dips.

 

Because one particular set of drying parameters was chosen for this study, the numbers in this report should not be regarded as absolute. However, for actual production, the results reported here should give foundrymen some idea as to how much strength is lost by insufficient drying.

Effect of Dilution on REMASOL® ADBOND® BV Binder

Increasing Cost Performance of this Industry Leading Binder

 

Manuel Guerra, October 1993

Presented at Investment Casting Institute Meeting

 

Since its market introduction in late 1992, REMASOLƒ‚® ADBONDƒ‚® BV binder has successfully replaced both ethyl silicate and other colloidal silica binders in foundries where fast processing times are required. Because of its good green strength, a reduction in autoclave cracking can also be realized.

Due to the variety of use conditions, additional work has been done with REMASOL ADBOND BV binder to determine the effect of dilution with respect to shell properties and improved cost performance. This paper updates that work.

P-10 Controlling Core Related Casting Defects

Glenn W. Schiefelbein, November 1992

 

Slide show in conjunction with Dipcoat Nucleation paper by R. Chester Feagin

 

This paper will give a brief summary of the generally accepted principles of nucleation, along with a brief review of the technical and patent literature relating to dipcoat nucleation. In addition, a description will be given of various experiments that have been carried out employing different nucleating agents. Several specific examples of grain size controlled castings produced in molds having nucleants on the mold surface will be shown as described.

P-9 Colloidal Silica in the Precision Casting Industry

 

Maintaining Performance in your Slurry

 

Glenn W. Schiefelbein, March 1987

 

Colloidal silica is the most popular binder used in the precision casting industry today. It is safe, economical, easy to use and performs well. All of these desirable attributes tend to lull us into a sense of well being when we use colloidal silica. We frequently forget that this workhorse of the industry is sensitive and needs some attention to keep it working at its best. This paper describes colloidal silica, its properties and those things that will affect its performance.

Ceramic Shell Production for Controlled Shell Cracking

12 Guidelines to Limit this Defect

 

Glenn W. Schiefelbein, June 1987

 

Shell cracking is the product of stresses applied during the shell building process. Factors that contribute to the stresses are identified. Practical methods to produce maximum green strength of shells are described. These include the process control of slurries and stucco, mechanics of shell building and drying. Twelve guidelines are given to ensure optimum shell strength to resist stresses that cause cracking.

Avoid Shell Cracking by Controlling Your Process

Reduce Likelihood of this Defect in Dewax

 

Craig T. Lanham, March 1995

 

A discussion focused on shell formulation, control and process to prevent stress on the ceramic shell, which can cause shell cracking.

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