1. Pinhole
Prohibit the use of contaminated aluminum alloy casting materials, organic compounds, and severe oxides to prevent the formation of pinholes on precision castings. Control the smelting process and strengthen degassing and refining. Control the thickness of the metal coating, as being too thick can easily create small holes. The temperature of the mold should not be too high, and cooling measures such as copper inlay or pouring should be taken at the thick wall position of the casting. When applying sand molds, water should be strictly controlled and dry cores should be used as much as possible.
2. Gas hole
Measures to prevent the formation of gas pores in investment casting precision casting: Improve the pouring and riser system to ensure smooth liquid flow and prevent gas entrainment. The mold and core should be preheated, then coated, and must be baked before use. Take sufficient exhaust measures to design the mold and core.
3. Oxidized slag inclusions
Measures to prevent oxidation weld nodules on investment casting furnace plates: Strictly control the smelting process, rapidly smelt, reduce oxidation, and completely discharge slag. Aluminum magnesium alloy must be melted under a covering agent. The furnace walls and tools should be cleaned and free of oxides, and should be preheated. The paint should be dry and dry after application. The designed forging system must have stable flow, buffering, and slag skimming capabilities. Choose an inclined pouring system to ensure smooth liquid flow without secondary oxidation. The selected coating has strong adhesion, and slag is generated in the casting during pouring without any peeling phenomenon.
4. Crack open
Measures to avoid hot cracking of investment casting valve bodies: In the specific pouring system, partial overheating should be prevented to reduce thermal stress. The mold and critical slope protection must be ensured to be above 5 °. When the riser is inverted, it can be formed by pulling the core, and the sand core can replace the metal key when necessary. Control the coating thickness to ensure consistent cooling speed of the casting. Select the appropriate mold temperature based on the thickness of the casting. Refine the alloy structure and improve the hot cracking ability. Improve the structure of castings, remove sharp corners and sudden changes in thickness, and reduce the tendency of hot cracks.
5. Loose
To ensure the ability to condense and shrink, and to avoid loose production measures: Reasonably set up vertical pipes. Moderately reduce the working temperature of metal molds. Control the thickness of the coating to make the thick walls thinner. Enable the thick wall of the casting to have greater cooling capacity and adjust the cooling speed of various components of the metal mold. The pouring temperature of the metal is moderately reduced.
