How can we avoid some common defects in metal precision castings

Common methods to avoid some defects in metal precision castings:

1. Needle eye

Countermeasures to avoid pinholes on high-precision castings: prohibit the use of environmentally polluted aluminum alloy casting raw materials, organic matter, and raw materials that are more severely oxidized. Operate the entire process of the smelter to improve degassing and refinement. Manipulate the thin and thick coatings of metal materials, too thick may cause pinholes. The mold temperature is not suitable for excessively high temperature, and refrigeration countermeasures such as copper inlay or pouring should be selected for the thin-walled 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

Countermeasures to avoid air vents: improve the pouring and riser system software to make the liquid flow smoothly and prevent gas from being brought in. The mold and the mold core should be heated, then glued, and must be baked before application. The mold and core design plan should take into account the use of adequate exhaust pipe countermeasures.

3. Air oxidation slag and impurities

Countermeasures to avoid air-oxidized welding tumors: strictly control the processing technology of the smelter, speed up the smelter, reduce air oxidation, and completely discharge the slag. Titanium-magnesium-aluminum alloy must be melted under the covering agent. Furnace walls and special tools should be cleaned without metal oxides and heated. The paint should be dry after application. The designed forging system software must have stable fluidity, buffering and slag skimming capabilities. The software of the skew pouring system is selected to make the liquid flow smoothly without secondary air oxidation. The selected coating has strong adhesion, and slag is generated in the casting during the whole pouring process without falling off.

4. Crack

Countermeasures to avoid thermal cracking: In the specific pouring system software, part of the over-temperature should be prevented to reduce thermal stress. The mold and the key slope protection must ensure the 5°, the inverted riser can be core-pulled and formed during condensation, and the sand core can replace the metal material when necessary. The thickness of the coating is controlled to ensure that the cooling rate of the casting is consistent. Choose the suitable mold temperature according to the thickness of the casting. Optimize the aluminum alloy structure to improve the hot cracking ability. Improve the structure of castings, remove sudden changes in bevel and wall thickness, and reduce the tendency of thermal cracks.

5. Loose

Countermeasures to avoid loose manufacturing: effective riser setting to ensure the ability to condense and gather. Moderately reduce the working temperature of metal material molds. To manipulate the thickness of the coating, the thin wall becomes soft. Adjust the cooling rate of each component of the metal material mold, so that the thin-walled casting has a greater cooling capacity. Moderately reduce the pouring temperature of metal materials.