Common defects in green sand casting and control methods to reduce scrap

Common Defects in Green Sand Casting and How DISOCO Controls Them to Ensure Quality
Green sand casting is an effective and flexible method for manufacturing mechanical parts in small to medium volumes. However, if factors such as sand moisture, metal temperature, and mold design are not properly controlled, defects like gas porosity, shrinkage, and dimensional deviation can easily occur, increasing the scrap rate. At DISOCO, we utilize an automatic sand molding system from Japan (SINTO), combined with SolidCast simulation software, strict quality inspection, and thorough personnel training as solutions to minimize defects and maintain stable quality.
■ Common Defects and Control Methods
• Gas porosity
Cause: High sand moisture, poor gas permeability
How DISOCO controls:
Controls moisture using a SINTO sand analyzer
Proper core treatment to increase gas permeability
• Shrinkage
Cause: Uneven cooling
How DISOCO controls:
Simulates flow & solidification process using SolidCast software
Optimizes gating system design
• Mismatch
Cause: Mold shift or improper fixturing
How DISOCO controls:
Uses a high-precision automatic sand molding machine
Standardizes mold patterns and fixturing process
• Poor surface finish, Burn-on
Cause: Excessively high temperature or poor sand quality
How DISOCO controls:
Manages pouring temperature using an automatic pouring system
Analyzes metal composition for each melt batch
• Blow holes
Cause: Air trapped in the mold
How DISOCO controls:
Optimizes venting system design
Designs and manufactures cores meeting gas permeability standards

■ Quality Control System at DISOCO
SINTO automatic sand molding machine (Japan): speed of 30 seconds/mold, casting weight up to 70kg/part.
Specialized casting sand management: analyzes compaction, moisture, and strength for each production shift.
SOLIDCast simulation software: predicts defects before casting, optimizes gating and cooling system design.
Post-casting inspection: CMM measurement, ultrasonic testing, magnetic particle inspection, hardness and chemical composition testing.
Thanks to operating an automatic green sand casting system and strict production process control, DISOCO not only reduces post-casting defects but also maintains stable quality to serve the Japanese, US markets, and FDI enterprises in Vietnam.
■ For details, please download the PDF or contact us directly if you are interested in green sand casting in Vietnam