Precision casting Machining is often avoided in defects

1. Pinhole: measures to prevent pinhole formation on precision casting parts: it is strictly prohibited to use contaminated casting aluminum alloy materials, organic compounds and seriously oxidized materials. Control smelting process and strengthen degassing refining. Control metal coating thickness, too thick easy to produce pinhole. The mold temperature should not be too high. The thick-walled parts of the casting should be cooled by measures such as copper inlaying or watering. When using sand mold, water should be strictly controlled and dry core should be used as far as possible.
 

2, Air hole: measures to prevent pores: improve the pouring and riser system, so that the liquid flow is stable, avoid air entrainment. Die and die core should be preheated, then coated, after the end of the must be baked before use. Die and core design should consider adequate venting measures.

 

3. Oxidation slag inclusions: measures to prevent oxidation slag inclusion: strict control of smelting process, rapid smelting, reduce oxidation, and thoroughly remove slag. Aluminum and magnesium alloys must be melted under a covering agent. Furnace body, tools should be clean, no oxide, and should be preheated, paint should be dry after use. The designed casting system must have stable flow, buffering and skimming capabilities. The inclined pouring system is adopted to make the liquid flow stable without secondary oxidation. The selected coating has strong adhesion and slag is formed in the casting during the pouring process without peeling.

 

4. Cracking: measures to prevent hot cracking: local overheating should be avoided in the actual pouring system and internal stress should be reduced. The mold and core slope must be ensured to be 5° above. The inverted riser can be cored during solidification, and the sand core can replace the metal core if necessary. Control the coating thickness to ensure the casting cooling rate is consistent. Select the appropriate die temperature according to the thickness of the casting. Refine alloy structure and improve hot cracking ability. Improve casting structure, eliminate sharp corners and wall thickness mutations, reduce the tendency of hot cracks.

 

5. Loose: measures to prevent loose production: reasonable riser setting to ensure solidification and shrinkage capacity. Reduce the working temperature of metal mold appropriately. Control coating thickness, thick wall thinning. Adjust the cooling speed of each part of the metal mold to make the thick wall of the casting have greater cooling capacity. Reduce metal pouring temperature appropriately.