Previously Asked Questions:
For Answers To Previously Asked Questions: Log Into Members Only Section
Beryllium Copper Alloy (4/5/2024)
We have been asked to quote a job in Beryllium Copper and have no experience with it. From the limited information I've found online, it seems like there are significant challenges associated with casting it. I am hoping to discuss these challenges with somebody that has experience with it.
Answer
Alloy Certifications Specifications (3/27/2024)
I am about to purchase some 1020 steel investment castings from a foundry, and I was just wondering, what are the typical certification specs that I can request from them?
Such as: adhering to ASTM A732, or ISO____, or porosity limits, or chemical/mechanical test reports, or defect free reports?
Answer
Foundry Dictionary (03/01/2022)
I am a student in a French engineer school. We address many subjects having the need of TOEIC English language proficiency test, however we don't have a professional English class which addressed foundry terms.
So I would like to create a specific dictionary with all regional synonyms, providing a good translation.
Currently, I use "Foundry Dictionary", an application on Playstore. It is very good and there are many definitions but it is not really complete, nor is it available in print or pdf.
Additionally, I would like to categorize each word for easier search. For example, shrinkage is a defect and sprue is a casting device.
Do you know of such a work? If not, do you know someone who would be willing to help me?
Answer
Non-HAPS Flux for Aluminum Melting (01/14/22)
The Air Quality department of our state is questioning whether the flux used at our foundry contained any hazardous materials. Who can I speak to about getting a non HAP's flux for aluminum melting? Typically, we use about 10 cups per year.
Answer
Slurry Viscosity Measurement (10/20/21)
We are having inconsistency measuring viscosity using the viscosity cup. Currently, we do the cup test every 2 hours and the plate weight once a shift. We are considering eliminating the viscosity cup test and do plate weight test every 2 hrs.. Is there a reason one would not want to only measure the plate weight?
Answer
3D Printer (10/06/21)
We need a 3D printer with the capacity to produce models up to 300mm. Please advise.
Answer
Standards Addressing Porosity in Investment Casting (07/28/21)
We are in the process of trying to locate some governing standards (such as ASME, ASTM, etc.) that address the issue of porosity in investment cast components. I was wondering if you could point me in the right direction.
Answer
Material Handling - Powders and Sands (06/29/21)
What is the industries preferred way of handling materials when it pertains to; lifting or moving 50# bags of sand and powders?
Answer
Metal Specifications (04/19/21)
I am a metallurgy and materials engineer, I have been working in an investment casting foundry as a production manager for about 2 years. Is there a standard accepted source on ICI metal specifications? and this resource should include chemical analysis and heat treatment and mechanical properties of the material.
Answer
Investment Casting Manganese Material(W.Nr.1.3401) (Mn12) (03/22/21)
A customer has placed an inquiry for parts cast in manganese alloy (W.Nr.1.3401). We are unfamiliar with this alloy and would like to know if it is cast-able using the investment casting process and are there aspects of casting this alloy of which we should be aware. Could the ICI please off some guidance in this area?
Answer
Pouring Temperatures (03/02/21)
I am trying to compile a chart for my boss about the necessary melting and pouring temperatures for specific grades of metals and I was wondering if you would have a good idea of resources to look up this information easily. I have tried looking through the ASTM Standards book as well as looking for resources online with not much to show for it and it would be a great help in building this chart to help our foundrymen. Thank you for your time and input.
Answer
Aluminum Test Bars (01/13/21)
I hope you can direct me to someone within your institution willing to share some advice on investment aluminum test bars. We have been experimenting here and are getting mixed results. I have reviewed the technical paper "The Effects On The Mechanical Properties When Using Different Geometry Testbar Coupons."
Per this technical paper, we ran several 1/4" diameter test bars out of 356-T6, with a pour temperature of 1400 deg F. and a mold temperature of 995 deg F., but we are experiencing strange results are within the same tree. We had bars pass comfortably and also fail miserably (very low elongation). The entire tree was heat-treated intact before the test bars are removed.
I did review the ask an expert question, "Improve Mechanical Properties of A357/A356/C355 Aluminum Castings (3/27/19)" We do add Tibor to our melt but not directly in the ladle like your answer suggested.
I have attached a couple of pictures showing our test bar shape and gaiting. We were concerned with the sharp radius of the end of the test bar, so we experimented with a few different shapes with no success.
Answer
We have been asked to quote a job in Beryllium Copper and have no experience with it. From the limited information I've found online, it seems like there are significant challenges associated with casting it. I am hoping to discuss these challenges with somebody that has experience with it.
Answer
Alloy Certifications Specifications (3/27/2024)
I am about to purchase some 1020 steel investment castings from a foundry, and I was just wondering, what are the typical certification specs that I can request from them?
Such as: adhering to ASTM A732, or ISO____, or porosity limits, or chemical/mechanical test reports, or defect free reports?
Answer
Foundry Dictionary (03/01/2022)
I am a student in a French engineer school. We address many subjects having the need of TOEIC English language proficiency test, however we don't have a professional English class which addressed foundry terms.
So I would like to create a specific dictionary with all regional synonyms, providing a good translation.
Currently, I use "Foundry Dictionary", an application on Playstore. It is very good and there are many definitions but it is not really complete, nor is it available in print or pdf.
Additionally, I would like to categorize each word for easier search. For example, shrinkage is a defect and sprue is a casting device.
Do you know of such a work? If not, do you know someone who would be willing to help me?
Answer
Non-HAPS Flux for Aluminum Melting (01/14/22)
The Air Quality department of our state is questioning whether the flux used at our foundry contained any hazardous materials. Who can I speak to about getting a non HAP's flux for aluminum melting? Typically, we use about 10 cups per year.
Answer
Slurry Viscosity Measurement (10/20/21)
We are having inconsistency measuring viscosity using the viscosity cup. Currently, we do the cup test every 2 hours and the plate weight once a shift. We are considering eliminating the viscosity cup test and do plate weight test every 2 hrs.. Is there a reason one would not want to only measure the plate weight?
Answer
3D Printer (10/06/21)
We need a 3D printer with the capacity to produce models up to 300mm. Please advise.
Answer
Standards Addressing Porosity in Investment Casting (07/28/21)
We are in the process of trying to locate some governing standards (such as ASME, ASTM, etc.) that address the issue of porosity in investment cast components. I was wondering if you could point me in the right direction.
Answer
Material Handling - Powders and Sands (06/29/21)
What is the industries preferred way of handling materials when it pertains to; lifting or moving 50# bags of sand and powders?
Answer
Metal Specifications (04/19/21)
I am a metallurgy and materials engineer, I have been working in an investment casting foundry as a production manager for about 2 years. Is there a standard accepted source on ICI metal specifications? and this resource should include chemical analysis and heat treatment and mechanical properties of the material.
Answer
Investment Casting Manganese Material(W.Nr.1.3401) (Mn12) (03/22/21)
A customer has placed an inquiry for parts cast in manganese alloy (W.Nr.1.3401). We are unfamiliar with this alloy and would like to know if it is cast-able using the investment casting process and are there aspects of casting this alloy of which we should be aware. Could the ICI please off some guidance in this area?
Answer
Pouring Temperatures (03/02/21)
I am trying to compile a chart for my boss about the necessary melting and pouring temperatures for specific grades of metals and I was wondering if you would have a good idea of resources to look up this information easily. I have tried looking through the ASTM Standards book as well as looking for resources online with not much to show for it and it would be a great help in building this chart to help our foundrymen. Thank you for your time and input.
Answer
Aluminum Test Bars (01/13/21)
I hope you can direct me to someone within your institution willing to share some advice on investment aluminum test bars. We have been experimenting here and are getting mixed results. I have reviewed the technical paper "The Effects On The Mechanical Properties When Using Different Geometry Testbar Coupons."
Per this technical paper, we ran several 1/4" diameter test bars out of 356-T6, with a pour temperature of 1400 deg F. and a mold temperature of 995 deg F., but we are experiencing strange results are within the same tree. We had bars pass comfortably and also fail miserably (very low elongation). The entire tree was heat-treated intact before the test bars are removed.
I did review the ask an expert question, "Improve Mechanical Properties of A357/A356/C355 Aluminum Castings (3/27/19)" We do add Tibor to our melt but not directly in the ladle like your answer suggested.
I have attached a couple of pictures showing our test bar shape and gaiting. We were concerned with the sharp radius of the end of the test bar, so we experimented with a few different shapes with no success.
Answer
|
|
Any advice, guidance, or reference material would be greatly appreciated.
Answer
Different process method called Water Glass and Zircon Silica Casting (04/17/20)
What's the materials and process used in these 2 different process?
And why Water glass process is cheaper then Zircon process?
And at last, what's the cost for subscription to this Portal? I'm working for SR tech Italy and we are not a foundry, we only import casting products from China.
Answer
Globally Sourced Casting Tolerances of Design (02/11/20)
For a globally sourced casting, should the tolerances of design be per "Investment Casting Handbook" or "ISO 8062-1 Dimensional Casting Tolerance Group(s)" ? One has geometry control while the other does not and the linear tables do not align....
Answer
Proposition 65 (02/11/20)
We are receiving requests from customers to certify that our castings are proposition 65 compliant. The castings in question are 17-4 stainless steel without any coatings. Has the ICI looked into proposition 65? A road map on how to verify that a casting is compliant would be nice. Please advise.
Answer
Fatigue Properties of Investment Cast Alloys (10/23/19)
I am a Lab Group Manager in GMR&D with responsibility for light metals research. The purpose of my note is if you can point me to a reference that would have fatigue properties of investment cast materials including aluminum alloys like 356 or related, 17-4 PH, titanium Ti64, and pure copper or close to it. (10/23/19)
Answer
Identification of Defect Type & Cause of the Defect (8/16/19)
Recently we cast Hast alloy C22 alloy casting for one of our valve customers. After knockout, we found finning type defect on the surface of the casting. When we try to repair it, it was peeled off continuously like some metallic secondary surface cover of casting. Can you guide me for identification of type of defect & cause of the defect?
Answer
Vendors that can perform the ash content test as specified in the ICI Standard Test Procedures for Pattern Materials (7/26/19)
I am looking for a list of vendors that can perform the ash content test as specified in the ICI Standard Test Procedures for Pattern Materials. The ash content test is also called determination of total ash. It is the first test in the ICI document.
Answer
Increasing Mechanical Properties of Aluminum Castings (4/23/19)
We would like to increase mechanical properties of aluminum castings at A357/E357 alloy considering: chemistry, heat treatment and dendrite arm spacing. Any recommendations?
Answer
Improve Mechanical Properties of A357/A356/C355 Aluminum Castings (3/27/19)
We would like to improve mechanical properties of A357/A356/C355 aluminum castings with refiners and/or modifiers. What kind of refiners/modifiers can be used? Quantities? How to use them? etc.
Answer
Typical Values for Shell Physical Properties (8/17/18)
I've been researching properties of shell molds for a recent project. I'm having trouble finding typical values for different physical properties and what the industry considers to be GOOD quality...
Properties like: green state MOR, Fired MO, Hot MOR...Density, Permeability etc...
Do typical values exist? Or is there a general understanding of minimum values?
Looking for some guidance if you can point me in a suitable direction.
Answer
Standard Values for Wax Physical Properties and Chemistry (8/15/18)
Currently I´m doing master thesis regarding the study of waxes.
I´m reaching you to ask if there are standard values for ash content, thermal contraction/expansion, viscosity, mechanical properties and melting point, for the reapplication of wax. In other words, is there are a limit/average value for the properties referred above. Better explained, I´m trying to understand what’s the limit number of refusion/reapplication of wax, without any treatment of purification.
Answer
Detection of Shrinkage in Airfoils (2/27/18)
There exists a critically urgent need to find a technique/supplier/source who possesses the ability to reliably detect internal (not connected to the surface) microshrink porosity located within solid, non-air-cooled, turbine engine blades. These blades are relatively small 1.5" long x .020"-.040" in the airfoil and .250 thick in the fir tree/platform.
The subject blade is vacuum cast in CMSX-6 nickel base single crystal material. This material is notorious for developing unusual amounts of microshrink/microporosity within the blade platform - airfoil base transition area during casting solidification. The porosity cannot be detected by standard radiography. The subject blades have been experiencing fatigue failure during engine operation which; most unfortunately, has resulted in several recent aircraft accidents which in turn, have resulted in passenger fatalities.
These blades are not cast, manufactured, or sold by our company, but the current situation has negatively affected several of our customers. Given the critical nature of the situation, we would like to identify a source who may possess a NDT - CT method capable of detecting the presence of microsink porosity in the CMSX-6 castings. We believe Computed Tomography (CT Radiography) may be an effective solution to detecting any potential presence of the subject porosity after the casting process.
I anyone has any relevant information please contact us. I deeply appreciate our help, if we can sove this issue this will, in my opinion, eliminate further loss of life.
Answer
Porosity (12/4/17)
We are pouring S7 and are having gas hole problems. We have trialed low nitrogen material using an Argon blanket to no avail. Any other tricks with this material?
Answer
Vacuum Heat Treatment (12/2/17)
Homogenizing the alloys to eliminate dendritic segregation appears to be right on the dot, especially the ductility. We have observed this in a few melts that we got vacuum heat treated. However, how vacuum HT smooths out the as-cast dendritic structure still beats me. Can the expert committee throw some light on this aspect?
Secondly, what in your opinion is the major difference in the variables between a sand foundry & an investment casting foundry? An article by a platinum jewel manufacturer spoke of “a process that really knows how to keep & guard its secrets”. If a sand casting foundry variables number say 1000 or so, will an investment casting foundry number its variables at 10,000 or more? We have noticed same castings manufactured 2 years ago never exhibited defects that are noticed today; so something has changed.
Answer
Vacuum Heat Treatment (7/13/17)
With regard to vacuum heat treatment, does it improve mechanical properties, especially ductility and toughness? I know that it totally eliminates surface oxidation of castings and associated defects. I have not been able to get any information on this.
Answer
Leaching With Potash (6/6/17)
Currently, I am working on a new leaching autoclave using potash but I have had difficulty finding the right leaching cycle (core material remains in the parts). I’m looking for information regarding leaching with potash, even if it’s not for the same application. Could you help me by providing some information about the use of potash (parameters, used process…)?
Answer
Follow Up To Cracking of 430SS Castings (5/9/17)
As a follow up to the Ask the Experts response regarding cracking of 430SS and the precautions required to reduce cracking:
1. Is hot straightening acceptable and what are the recommended hot straightening temperatures?
2. If I wanted to purchase hot straightening jigs, where might I turn to?
3. What is the recommended preheat temperature for welding?
4. Are there any special culprits such as C , N , O or others which should be controlled?
Answer
Pin Holes (5/8/17)
On a well-established, robust process, we suddenly began witnessing perfect little pin holes in the resulting parts. We have never had this problem before, and they look exactly like the gas (air entrapment)as described in your Atlas of Casting Defects book page 9. We cannot figure out why all of a sudden this is starting to happen we have not changed anything in our process. We pour right at the cup and the venting is the same we have used for years. The only thing different is that we have a new employee helping with the pouring. Could this possible cause the problem?
Also is there anything we can add to 440-C to help de-gas it to help fix this if that is what is going on and if so why would we all of a sudden have to use an additive to de-gas when we never have before? We have not changed anything in the shelling process, it is all the same as before we started to get these holes. They are causing us to have a lot of scrap in our parts. Just trying to cover all our bases and get this figured out. Any information you can give us on this would be greatly appreciated.
Answer
Cracking of 430SS Castings (April 29, 2017)
Our company shies away from 430SS as past experience has shown that the alloy is prone to cracking. Is this especially true of this alloy? And how would one work around this problem?
Answer
Colloidal Silica Publications and Support (1/25/2017)
ICI publication list makes no mention of Colloidal Silica, its specifications nor the effect the various properties have on the quality of investment castings produced. For example, effect of Colloidal Silica surface area, particle size, pH, etc. have on the stability, bonding strength, etc. of prime coat slurry, back-up slurry. Can the ICI recommend a good publication for this binder? Alternatively, can the Experts Committee recommend their advice / suggestions on this issue?
Answer
Part Cracking (12/19/2016)
We are experiencing cracking on the edge of an A357 casting. The defect only occurs on one of the four parts in the mold cluster. Any ideas?
Answer
Shelling of Core Passages (12/5/2016)
We have a valve part that we are trying to shell a core passage of approximately 9 mm diameter and over 25 mm long on both sides of the body. We are getting shell cracking in the 9 mm hole. We are using pre-coats of zircon (first dip slurry) till the hole is filled completely, as back up coats are not possible in such a small area. We have standard 325 zircon slurry with 30 % Colloidal and 70% as water. Is there any other way to coat this small diameter or change/add/remove slurry mixture materials for proper dying in first few coats for more strength? We cannot use a ceramic core as per customer requirements.
Answer
Use of Plasticizers (10/13/2016)
I want to understand more on the use of plasticizers in the formation of investment casting patterns. I am currently writing a Ph.D. proposal on the production of investment casting patterns from thermoplastics. Is there anyone with which I can contact to discuss plasticizers in wax patterns? Are there any reference materials available?
Answer
Shell Removal for Art Quality Silicone Bronze Parts (10/3/2016)
Our company is having art quality silicone bronze parts shell cast. The company doing this has normally sand blasted the shells to remove them. However, because of the gold-like mirror polish that we desire for these castings, sand blasting of any to-be-exposed outer surfaces is out of the question. We need expert recommendations how to get the most hard shell material out of important nooks and crannies on our castings. Physical vibration would likely damage the S. bronze. A product with a decade-long development is hinging on finding how to get the shell to come off of the castings. We sincerely hope you can help.
Answer
Answer
Different process method called Water Glass and Zircon Silica Casting (04/17/20)
What's the materials and process used in these 2 different process?
And why Water glass process is cheaper then Zircon process?
And at last, what's the cost for subscription to this Portal? I'm working for SR tech Italy and we are not a foundry, we only import casting products from China.
Answer
Globally Sourced Casting Tolerances of Design (02/11/20)
For a globally sourced casting, should the tolerances of design be per "Investment Casting Handbook" or "ISO 8062-1 Dimensional Casting Tolerance Group(s)" ? One has geometry control while the other does not and the linear tables do not align....
Answer
Proposition 65 (02/11/20)
We are receiving requests from customers to certify that our castings are proposition 65 compliant. The castings in question are 17-4 stainless steel without any coatings. Has the ICI looked into proposition 65? A road map on how to verify that a casting is compliant would be nice. Please advise.
Answer
Fatigue Properties of Investment Cast Alloys (10/23/19)
I am a Lab Group Manager in GMR&D with responsibility for light metals research. The purpose of my note is if you can point me to a reference that would have fatigue properties of investment cast materials including aluminum alloys like 356 or related, 17-4 PH, titanium Ti64, and pure copper or close to it. (10/23/19)
Answer
Identification of Defect Type & Cause of the Defect (8/16/19)
Recently we cast Hast alloy C22 alloy casting for one of our valve customers. After knockout, we found finning type defect on the surface of the casting. When we try to repair it, it was peeled off continuously like some metallic secondary surface cover of casting. Can you guide me for identification of type of defect & cause of the defect?
Answer
Vendors that can perform the ash content test as specified in the ICI Standard Test Procedures for Pattern Materials (7/26/19)
I am looking for a list of vendors that can perform the ash content test as specified in the ICI Standard Test Procedures for Pattern Materials. The ash content test is also called determination of total ash. It is the first test in the ICI document.
Answer
Increasing Mechanical Properties of Aluminum Castings (4/23/19)
We would like to increase mechanical properties of aluminum castings at A357/E357 alloy considering: chemistry, heat treatment and dendrite arm spacing. Any recommendations?
Answer
Improve Mechanical Properties of A357/A356/C355 Aluminum Castings (3/27/19)
We would like to improve mechanical properties of A357/A356/C355 aluminum castings with refiners and/or modifiers. What kind of refiners/modifiers can be used? Quantities? How to use them? etc.
Answer
Typical Values for Shell Physical Properties (8/17/18)
I've been researching properties of shell molds for a recent project. I'm having trouble finding typical values for different physical properties and what the industry considers to be GOOD quality...
Properties like: green state MOR, Fired MO, Hot MOR...Density, Permeability etc...
Do typical values exist? Or is there a general understanding of minimum values?
Looking for some guidance if you can point me in a suitable direction.
Answer
Standard Values for Wax Physical Properties and Chemistry (8/15/18)
Currently I´m doing master thesis regarding the study of waxes.
I´m reaching you to ask if there are standard values for ash content, thermal contraction/expansion, viscosity, mechanical properties and melting point, for the reapplication of wax. In other words, is there are a limit/average value for the properties referred above. Better explained, I´m trying to understand what’s the limit number of refusion/reapplication of wax, without any treatment of purification.
Answer
Detection of Shrinkage in Airfoils (2/27/18)
There exists a critically urgent need to find a technique/supplier/source who possesses the ability to reliably detect internal (not connected to the surface) microshrink porosity located within solid, non-air-cooled, turbine engine blades. These blades are relatively small 1.5" long x .020"-.040" in the airfoil and .250 thick in the fir tree/platform.
The subject blade is vacuum cast in CMSX-6 nickel base single crystal material. This material is notorious for developing unusual amounts of microshrink/microporosity within the blade platform - airfoil base transition area during casting solidification. The porosity cannot be detected by standard radiography. The subject blades have been experiencing fatigue failure during engine operation which; most unfortunately, has resulted in several recent aircraft accidents which in turn, have resulted in passenger fatalities.
These blades are not cast, manufactured, or sold by our company, but the current situation has negatively affected several of our customers. Given the critical nature of the situation, we would like to identify a source who may possess a NDT - CT method capable of detecting the presence of microsink porosity in the CMSX-6 castings. We believe Computed Tomography (CT Radiography) may be an effective solution to detecting any potential presence of the subject porosity after the casting process.
I anyone has any relevant information please contact us. I deeply appreciate our help, if we can sove this issue this will, in my opinion, eliminate further loss of life.
Answer
Porosity (12/4/17)
We are pouring S7 and are having gas hole problems. We have trialed low nitrogen material using an Argon blanket to no avail. Any other tricks with this material?
Answer
Vacuum Heat Treatment (12/2/17)
Homogenizing the alloys to eliminate dendritic segregation appears to be right on the dot, especially the ductility. We have observed this in a few melts that we got vacuum heat treated. However, how vacuum HT smooths out the as-cast dendritic structure still beats me. Can the expert committee throw some light on this aspect?
Secondly, what in your opinion is the major difference in the variables between a sand foundry & an investment casting foundry? An article by a platinum jewel manufacturer spoke of “a process that really knows how to keep & guard its secrets”. If a sand casting foundry variables number say 1000 or so, will an investment casting foundry number its variables at 10,000 or more? We have noticed same castings manufactured 2 years ago never exhibited defects that are noticed today; so something has changed.
Answer
Vacuum Heat Treatment (7/13/17)
With regard to vacuum heat treatment, does it improve mechanical properties, especially ductility and toughness? I know that it totally eliminates surface oxidation of castings and associated defects. I have not been able to get any information on this.
Answer
Leaching With Potash (6/6/17)
Currently, I am working on a new leaching autoclave using potash but I have had difficulty finding the right leaching cycle (core material remains in the parts). I’m looking for information regarding leaching with potash, even if it’s not for the same application. Could you help me by providing some information about the use of potash (parameters, used process…)?
Answer
Follow Up To Cracking of 430SS Castings (5/9/17)
As a follow up to the Ask the Experts response regarding cracking of 430SS and the precautions required to reduce cracking:
1. Is hot straightening acceptable and what are the recommended hot straightening temperatures?
2. If I wanted to purchase hot straightening jigs, where might I turn to?
3. What is the recommended preheat temperature for welding?
4. Are there any special culprits such as C , N , O or others which should be controlled?
Answer
Pin Holes (5/8/17)
On a well-established, robust process, we suddenly began witnessing perfect little pin holes in the resulting parts. We have never had this problem before, and they look exactly like the gas (air entrapment)as described in your Atlas of Casting Defects book page 9. We cannot figure out why all of a sudden this is starting to happen we have not changed anything in our process. We pour right at the cup and the venting is the same we have used for years. The only thing different is that we have a new employee helping with the pouring. Could this possible cause the problem?
Also is there anything we can add to 440-C to help de-gas it to help fix this if that is what is going on and if so why would we all of a sudden have to use an additive to de-gas when we never have before? We have not changed anything in the shelling process, it is all the same as before we started to get these holes. They are causing us to have a lot of scrap in our parts. Just trying to cover all our bases and get this figured out. Any information you can give us on this would be greatly appreciated.
Answer
Cracking of 430SS Castings (April 29, 2017)
Our company shies away from 430SS as past experience has shown that the alloy is prone to cracking. Is this especially true of this alloy? And how would one work around this problem?
Answer
Colloidal Silica Publications and Support (1/25/2017)
ICI publication list makes no mention of Colloidal Silica, its specifications nor the effect the various properties have on the quality of investment castings produced. For example, effect of Colloidal Silica surface area, particle size, pH, etc. have on the stability, bonding strength, etc. of prime coat slurry, back-up slurry. Can the ICI recommend a good publication for this binder? Alternatively, can the Experts Committee recommend their advice / suggestions on this issue?
Answer
Part Cracking (12/19/2016)
We are experiencing cracking on the edge of an A357 casting. The defect only occurs on one of the four parts in the mold cluster. Any ideas?
Answer
Shelling of Core Passages (12/5/2016)
We have a valve part that we are trying to shell a core passage of approximately 9 mm diameter and over 25 mm long on both sides of the body. We are getting shell cracking in the 9 mm hole. We are using pre-coats of zircon (first dip slurry) till the hole is filled completely, as back up coats are not possible in such a small area. We have standard 325 zircon slurry with 30 % Colloidal and 70% as water. Is there any other way to coat this small diameter or change/add/remove slurry mixture materials for proper dying in first few coats for more strength? We cannot use a ceramic core as per customer requirements.
Answer
Use of Plasticizers (10/13/2016)
I want to understand more on the use of plasticizers in the formation of investment casting patterns. I am currently writing a Ph.D. proposal on the production of investment casting patterns from thermoplastics. Is there anyone with which I can contact to discuss plasticizers in wax patterns? Are there any reference materials available?
Answer
Shell Removal for Art Quality Silicone Bronze Parts (10/3/2016)
Our company is having art quality silicone bronze parts shell cast. The company doing this has normally sand blasted the shells to remove them. However, because of the gold-like mirror polish that we desire for these castings, sand blasting of any to-be-exposed outer surfaces is out of the question. We need expert recommendations how to get the most hard shell material out of important nooks and crannies on our castings. Physical vibration would likely damage the S. bronze. A product with a decade-long development is hinging on finding how to get the shell to come off of the castings. We sincerely hope you can help.
Answer
