How to solve the cold insulation defect of precision casting
Underpouring and cold shut in investment casting are very common defects in forging. In many cases, these two defects rank at the top of completely damaged castings. Underpouring means that the metal liquid cannot fill the casting cavity, resulting in incomplete castings. .The characteristics of this defect are that there are smooth round-edged holes in the inner wall of the casting, or that one or several tail ends of the casting are not filled with metal liquid; cold partition refers to the obvious discontinuity defect where the double-stranded metal gathers, because it cannot Completely welded. The appearance of this defect usually appears as cracks or wrinkles with smooth edges. Characteristics of these 2 defects:
1. It is easy to find during casting inspection; 2. In addition to the cleaning process, almost every forging process has its reasons. Next, the causes and countermeasures of insufficient pouring of castings and cold isolation will be introduced.
Causes:
1. Low temperature or low temperature molten metal or low mold temperature;
2. The alloy composition does not meet the regulations and has poor fluidity;
3. Add molten metal to divide the parts, resulting in poor welding;
4. The gate is unscientific and the steps are too long;
5. Low speed or poor exhaust;
6. The injection ratio is a little lower.
Countermeasures:
1. The product turns black with flow marks. Moderately increase the pouring temperature and mold temperature; observe the mold temperature and reduce the coating spray
2. Change the alloy composition and improve fluidity;
3. When ironing the mold, you can see the inflow of aluminum liquid, and the cold insulation caused by the impact of the metal liquid is generally a vortex, accompanied by flow marks. Improve the pouring system and increase the charging direction of the inner gate. In addition, a slag collection bag can be set at the edge of the casting. Improve charging standards;
4. The far side is not pressed firmly. Change the gate position and cross-sectional area, improve the overflow standard, and increase the overflow amount;
5. Processing precision casting manufacturers change the flow rate of metal liquid to increase the injection rate;
6. The overall casting is not pressed firmly. Increase the specific pressure (try not to choose this option). If conditions permit, it can be improved to a large-tonnage machine.
