Chemically Bonded Defects Panel
Chemically Bonded Defects Panel Randal Campbell – HA International Giuseppe Iorio – Naval Surface Warfare Center Joe Muniza – ASK Chemicals Mitchell Patterson – HA International Ayax Rangel – HA International Ralph Showman – ASK Chemicals AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
What’s “Special” about Chemically Bonded Molds/Cores • Sand coated w/ binder to create a resin bridge
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Chemical Binder Types • In-organic – Silicates
• Organic – Phenolic Urethane – Furan – Acrylic / Epoxy – Ester-cured Phenolic AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Production Methods • Hot / Warm box – Heat cured
• Coldbox – Gas catalyzed
• Nobake – Liquid catalyzed
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
How does the chemical binder relate to casting defects? • Binder cure mechanisms – Production method
• Binder decomposition – Decomposition products – Decomposition mechanism
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Defects Related to Chemical Binders • • • • •
Erosion Veining Scabbing Penetration Warpage
• • • • • •
Blows Gas porosity Nitrogen fissures Hot tears Lustrous carbon Flake skin
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Erosion What is it? • A projection of metal outside the desired shape and into the molding material where the core sand was washed away
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Erosion Causes • Insufficient sand cohesion • Poor compaction • Poor gating design • Aggregate insufficient
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Erosion Potential Solutions • Increase binder level • Use binder with higher hot strength • Improve compaction – harder, more uniform ramming
• Use a refractory coating / more resistant refractory • Modify aggregate – in total or facing problem area • Re-design the gating system • Use ceramic gates or strainer cores
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Background • Casting is a process which carries risk of failure occurrence during all the process of accomplishment of the finished product • The correct identification of the casting defect at the initial stage is essential for taking remedial actions • This presentation summarizes casting defects involved with various casting processes AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Lustrous carbon defects What is it? •
Lustrous carbon forms on inert surfaces through thermal decomposition of hydrocarbon-bearing gases in reducing atmospheres above 650°C.
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Lustrous carbon defects What is it? • Lustrous carbon is deposited as a film on the silica grains of the mould. Relatively thick layers of lustrous carbon film can result from the gas pressure which develops, particularly when deposited on core sections AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Possible Causes • Resin-bonded sand • Lustrous carbon producing capacity of the core binder too high • Insufficient venting of core gases.
• Gating and pouring practice • Too much turbulence, leading to inclusion of lustrous carbon • Pouring temperature too low
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Metal Penetration What is it? • A projection of metal outside the desired shape and into the molding material • AKA burn-In, fuzz, etc
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Metal Penetration Causes • Poor sand compaction • Excessive binder • Refractory failure • Low surface tension alloy
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Metal Penetration Potential Solutions • Modify compaction method
• Lengthen work time • Increase bench life, or blow cores within bench life • Decrease binder
• Choose alternate binder • Use a refractory coating • Modify aggregate • Reduce pouring temperature • Modify alloy AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Veining What is it? • An expansion defect caused by fissures in the core / mold • Lines of extra metal that look like veins appear on the surface of the casting
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Veining Causes • Mainly related to aggregate expansion
• Binder thermal properties play a role in veining • Expansion exceeding the deformability and ultimately lessening core strength
•
Common in sharp angles and curve shapes Stress caused by sand expansion
Damaged section
Sand grains
Veining
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Veining Potential Solutions • Aggregate selection • Sand additives
• Binder system • Right level of compaction • Pouring temperature
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Gas Defects What is it? • Gases dissolved in the metal are expelled during solidification • External gas pressure creates a “bubble” and the metal solidifies around it.
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Gas Defects Causes • Moisture / Water • High LOI • Lack of Venting • Low pouring temp
• N2 content of binder
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Gas Defects Potential Solutions • Control Moisture in sand and in compressed air
• Optimized binder type • Optimized binder levels • Titanium additions 0.02 – 0.04% • Optimized venting practices • Optimized metal pour temperature
• Desiccant dryers on Part II
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Metallurgical Surface Defects
10x
100x
100x AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Defect Causes • The sand mold is very insulating and casting temperature remains high for an extended time • Decomposition of the organic binder creates an atmosphere rich in CO with some N • This could be described as “heat treatment” • Shakeout time determines casting temperature and “quench”
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Defect Prevention • Control gas composition – Binder type – Additives – Venting
• Control “quench” – Shakeout time & temp
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Defect Potential by Binder System 1: Least Susceptible - 4: Most Susceptible
Core Float/Shift in Casting Core Warpage Gas Blow Hot Tears Erosion Burn In (Poor Density) Lustrous Carbon Veining
Urethane 4 3 4 2 3 2 4 3
Urethane Nitrogen
Acid Cured 2 2 2 1 4 3 1 2
Alkaline Phenolic 2 4 1 3 2 3 1 1
Defects Unique to Binder Chemistry Acid Cured Alkaline Phenolic Sintering (salt buildSulfur Pick-Up up) Blows (uncured Blows (uncured center) center)
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Shell 1 1 3 4 1 1 3 3
Shell Nitrogen
QUESTIONS???
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
For additional information, please contact: [email protected] [email protected] [email protected]
[email protected] [email protected] [email protected] AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Instructions SUBMISSION:
All PowerPoint Presentations are due at AFS by September 13, 2013 Submit to [email protected] Or by FTP Site: http://www.afsinc.net/uploadsite/index.asp Username: consultant Password: safe AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
What’s “Special” about Chemically Bonded Molds/Cores • Sand coated w/ binder to create a resin bridge
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Chemical Binder Types • In-organic – Silicates
• Organic – Phenolic Urethane – Furan – Acrylic / Epoxy – Ester-cured Phenolic AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Production Methods • Hot / Warm box – Heat cured
• Coldbox – Gas catalyzed
• Nobake – Liquid catalyzed
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
How does the chemical binder relate to casting defects? • Binder cure mechanisms – Production method
• Binder decomposition – Decomposition products – Decomposition mechanism
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Defects Related to Chemical Binders • • • • •
Erosion Veining Scabbing Penetration Warpage
• • • • • •
Blows Gas porosity Nitrogen fissures Hot tears Lustrous carbon Flake skin
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Erosion What is it? • A projection of metal outside the desired shape and into the molding material where the core sand was washed away
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Erosion Causes • Insufficient sand cohesion • Poor compaction • Poor gating design • Aggregate insufficient
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Erosion Potential Solutions • Increase binder level • Use binder with higher hot strength • Improve compaction – harder, more uniform ramming
• Use a refractory coating / more resistant refractory • Modify aggregate – in total or facing problem area • Re-design the gating system • Use ceramic gates or strainer cores
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Background • Casting is a process which carries risk of failure occurrence during all the process of accomplishment of the finished product • The correct identification of the casting defect at the initial stage is essential for taking remedial actions • This presentation summarizes casting defects involved with various casting processes AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Lustrous carbon defects What is it? •
Lustrous carbon forms on inert surfaces through thermal decomposition of hydrocarbon-bearing gases in reducing atmospheres above 650°C.
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Lustrous carbon defects What is it? • Lustrous carbon is deposited as a film on the silica grains of the mould. Relatively thick layers of lustrous carbon film can result from the gas pressure which develops, particularly when deposited on core sections AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Possible Causes • Resin-bonded sand • Lustrous carbon producing capacity of the core binder too high • Insufficient venting of core gases.
• Gating and pouring practice • Too much turbulence, leading to inclusion of lustrous carbon • Pouring temperature too low
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Metal Penetration What is it? • A projection of metal outside the desired shape and into the molding material • AKA burn-In, fuzz, etc
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Metal Penetration Causes • Poor sand compaction • Excessive binder • Refractory failure • Low surface tension alloy
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Metal Penetration Potential Solutions • Modify compaction method
• Lengthen work time • Increase bench life, or blow cores within bench life • Decrease binder
• Choose alternate binder • Use a refractory coating • Modify aggregate • Reduce pouring temperature • Modify alloy AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Veining What is it? • An expansion defect caused by fissures in the core / mold • Lines of extra metal that look like veins appear on the surface of the casting
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Veining Causes • Mainly related to aggregate expansion
• Binder thermal properties play a role in veining • Expansion exceeding the deformability and ultimately lessening core strength
•
Common in sharp angles and curve shapes Stress caused by sand expansion
Damaged section
Sand grains
Veining
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Veining Potential Solutions • Aggregate selection • Sand additives
• Binder system • Right level of compaction • Pouring temperature
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Gas Defects What is it? • Gases dissolved in the metal are expelled during solidification • External gas pressure creates a “bubble” and the metal solidifies around it.
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Gas Defects Causes • Moisture / Water • High LOI • Lack of Venting • Low pouring temp
• N2 content of binder
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Gas Defects Potential Solutions • Control Moisture in sand and in compressed air
• Optimized binder type • Optimized binder levels • Titanium additions 0.02 – 0.04% • Optimized venting practices • Optimized metal pour temperature
• Desiccant dryers on Part II
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Metallurgical Surface Defects
10x
100x
100x AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Defect Causes • The sand mold is very insulating and casting temperature remains high for an extended time • Decomposition of the organic binder creates an atmosphere rich in CO with some N • This could be described as “heat treatment” • Shakeout time determines casting temperature and “quench”
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Defect Prevention • Control gas composition – Binder type – Additives – Venting
• Control “quench” – Shakeout time & temp
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Defect Potential by Binder System 1: Least Susceptible - 4: Most Susceptible
Core Float/Shift in Casting Core Warpage Gas Blow Hot Tears Erosion Burn In (Poor Density) Lustrous Carbon Veining
Urethane 4 3 4 2 3 2 4 3
Urethane Nitrogen
Acid Cured 2 2 2 1 4 3 1 2
Alkaline Phenolic 2 4 1 3 2 3 1 1
Defects Unique to Binder Chemistry Acid Cured Alkaline Phenolic Sintering (salt buildSulfur Pick-Up up) Blows (uncured Blows (uncured center) center)
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Shell 1 1 3 4 1 1 3 3
Shell Nitrogen
QUESTIONS???
AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
For additional information, please contact: [email protected] [email protected] [email protected]
[email protected] [email protected] [email protected] AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
Instructions SUBMISSION:
All PowerPoint Presentations are due at AFS by September 13, 2013 Submit to [email protected] Or by FTP Site: http://www.afsinc.net/uploadsite/index.asp Username: consultant Password: safe AFS Sand Casting Conference October 20-22, 2014 – Indianapolis, IN USA
