Introducing various metal casting defects with many pictures by Dandong Foundry in China. These are the common sand casting defects on the surface and inside of cast iron and cast steel parts.
1. Blowhole is a kind of cavities defect, which is also divided into pinhole and subsurface blowhole. Pinhole is very tiny hole. Subsurface blowhole only can be seen after machining.
2. Burning-on defect is also called as sand burning, which includes chemical burn-on, and metal penetration.
3. Sand inclusion and slag inclusion are also called as scab or blacking scab. They are inclusion defects. Looks like there are slag inside of metal castings.
4. Sand hole is a kind of shrinkage cavity defect. They are empty holes after sand blasting.
5. Cold lap or also called as cold shut. It is a crack with round edges. Cold lap is because of low melting temperature or poor gating system.
6. Joint flash is also called as casting fin, which is a thin projection out of surface of metal castings. Joint flash should be removed during cleaning and grinding process.
7. Misrun defect is a kind of incomplete casting defect, which causes the casting uncompleted. The edge of defect is round and smooth.
8. Shrinkage defects include dispersed shrinkage, micro-shrinkage and porosity.
9. Shrinkage cavities are also called as shrinkage holes, which is a type of serious shrinkage defect.
10. Shrinkage depression is also a type of shrinkage defect, which looks like depressed region on the surface of metal castings.
11. Elephant skin is a type of surface defect, which cause irregular or wrinkle shapes surfaces.
12. Veins defect is also called as rat tail, which looks like many small water flow traces on the surface of metal castings.
13. Rough surface, coarse surface is also a kind of surface defect. Normal rough surfaces can not be judged as defects, but too rough and uneven in surface will be a defect.
14. Mismatch in mold defect is because of the shifting molding flashes. It will cause the dislocation at the parting line.
15. Mechanical damage is because the damage during machining or delivery processes.
16. Slag inclusion is also called as exogenous inclusion, entrapped slag.
17. Raised mold defect. Because of the flotage of liquid metal, the mould flasks are raised, which caused the top part of casting become higher or thicker than lower part.
18. Crack defects normally happen inside of metal castings. This defect will reduce the physical properties of metal castings.
19. Abnormal nodulizing or under-nodulizing defects. Because of many reasons, the spheroidization of graphite for ductile iron will be affected, therefore, caused the bad spheroidization rate.
20. Uneven hardness defect means the uneven hardness on the same surfaces. When machining to harder positions, the machining will become more difficult.
21. Sand drop is also called as sand crush. The sand mold drops part of sand blocks, so they will cause the similar shaped sand holes or incomplete.