1. Pinholes

Measures to prevent pinholes on precision castings: Strictly prohibit the use of contaminated casting aluminum alloy materials, organic compounds, and severely oxidized materials. Control the smelting process and strengthen degassing and refining. Control the thickness of the metal coating; excessive thickness easily causes pinholes. The mold temperature should not be too high; cooling measures should be applied to thick-walled parts of the casting, such as copper inserts or water spraying. When using sand molds, strictly control the water content and try to use dry cores.

2. Air Holes

Measures to prevent air holes: Improve the pouring and riser system to ensure stable liquid flow and avoid air entrapment. Molds and cores should be preheated, then coated, and must be baked before use after coating. The design of molds and cores should consider sufficient venting measures.

3. Oxide and Slag Inclusions

Measures to prevent oxide and slag inclusions: Strictly control the smelting process, smelt quickly to reduce oxidation, and thoroughly remove slag. Aluminum-magnesium alloys must be melted under a covering agent. Furnaces and tools should be clean, free of oxides, and preheated; paint should be dried after use. The designed casting system must have stable flow, buffering, and slag removal capabilities. Use an inclined pouring system to ensure stable liquid flow and prevent secondary oxidation. Selected coatings should have strong adhesion; slag formed during pouring should remain inside the casting without peeling.

4. Cracking

Measures to prevent hot cracking: Avoid local overheating in the actual pouring system to reduce internal stress. The mold and core slopes must ensure the above 5° angle; risers can be withdrawn after solidification to form cores, and sand cores can replace metal cores when necessary. Control coating thickness to ensure consistent cooling speed of the casting. Select appropriate mold temperature based on casting thickness. Refine alloy structure to improve hot cracking resistance. Improve casting structure by eliminating sharp corners and sudden wall thickness changes to reduce hot crack tendency.

5. Looseness

Measures to prevent looseness during production: Reasonable riser arrangement to ensure solidification and shrinkage capacity. Appropriately reduce the working temperature of metal molds. Control coating thickness and thin thick walls. Adjust the cooling speed of various parts of the metal mold to provide greater cooling capacity for thick-walled castings. Appropriately reduce metal pouring temperature.