17 Causes and Solutions for Common Types of Casting Defects

Introduction

Casting is a manufacturing process used in many industries to produce complex metal shapes. Although casting can provide excellent results, it is not without its potential problems. In this article we will discuss 17 common types of casting defects, their causes and possible solutions.

Types of Casting Defects

1. Porosity
• Cause: Gas trapped in the mold cavity during solidification.
• Solution: Vacuum degassing or pressure casting.
2. Cold Shut
• Cause: Insufficient molten metal or an incorrect pouring temperature.
• Solution: Adjust the pouring temperature and/or increase the amount of molten metal.
3. Mismatch
• Cause: Uneven cooling or inadequate venting.
• Solution: Ensure good ventilation and reduce the cooling rate by increasing the thickness of the walls.
4. Hot Tearing
• Cause: Poor mould design, incorrect pouring temperature, or insufficient lubrication.
• Solution: Increase the pouring temperature, reduce the wall thickness, and/or add lubricant to the mould.
5. Shrinkage Cavities
• Cause: Insufficient molten metal or incorrect pouring temperature.
• Solution: Increase the amount of molten metal or adjust the pouring temperature.
6. Gas Porosity
• Cause: Air bubbles trapped in the mould during solidification.
• Solution: Vacuum degassing or pressure casting.
7. Mold Shift
• Cause: Poorly designed moulds or inadequate support.
• Solution: Design better moulds or add additional support.
8. Sand Inclusions
• Cause: Poor quality sand or inadequate mould sealing.
• Solution: Use higher quality sand and ensure adequate sealing.
9. Incomplete Filling
• Cause: Insufficient molten metal or incorrect pouring temperature.
• Solution: Increase the amount of molten metal or adjust the pouring temperature.
10. Scabbing
• Cause: Poor mould design or inadequate venting.
• Solution: Design better moulds or add additional vents.
11. Misalignment
• Cause: Poorly designed moulds or inadequate support.
• Solution: Design better moulds or add additional support.
12. Erosion
• Cause: Poor quality sand or inadequate mould sealing.
• Solution: Use higher quality sand and ensure adequate sealing.
13. Dross Formation
• Cause: Poor mould design, incorrect pouring temperature, or inadequate venting.
• Solution: Design better moulds, adjust the pouring temperature, and/or add additional vents.
14. Slag Inclusions
• Cause: Poor mould design, incorrect pouring temperature, or inadequate venting.
• Solution: Design better moulds, adjust the pouring temperature, and/or add additional vents.
15. Mould Misalignment
• Cause: Poorly designed moulds or inadequate support.
• Solution: Design better moulds or add additional support.
16. Flash
• Cause: Poor mould design, incorrect pouring temperature, or inadequate venting.
• Solution: Design better moulds, adjust the pouring temperature, and/or add additional vents.
17. Turbulence
• Cause: Poor mould design, incorrect pouring temperature, or inadequate venting.
• Solution: Design better moulds, adjust the pouring temperature, and/or add additional vents.
18. Surface Defects
• Cause: Poor mould design or inadequate venting.
• Solution: Design better moulds or add additional vents.

Conclusion

Casting is a highly versatile and reliable manufacturing process, but it can also be prone to certain defects. The good news is that most of these defects can be avoided or minimized with proper design and maintenance. By understanding the causes and solutions for common casting defects, you can ensure that your castings are of the highest quality.