Possible problems with alloy castings?

Possible problems with alloy castings?
It is well known that investment casting produces castings with high precision and good finish. However, many common casting defects may exist during the production process of investment casting. Based on our engineering experience and advanced equipment, we can find ways to prevent such problems by analyzing the causes.
In the following, we introduce several common casting defects and their causes and prevention methods. We hope this article helps our customers to understand the problem and our colleagues, and this analysis can help you to prevent possible casting defects.
Bottom casting and cold barrier
1、Problem description.
Bottom casting is often in the casting thin wall or away from the inner runner at the local lack of flesh, the edge is curved. Cold barrier is the two strands of molten metal are not completely fused, there is a clear joint.
2. Causes.
1) low metal liquid pouring temperature and mold temperature
2) Slow pouring speed or unreasonable setting of flow channel, metal flow is too long
3) Casting wall thickness is too thin, metal liquid flow is not good
4) cut off when pouring
3. Preventive measures.
1) Increase the pouring temperature of metal liquid and mold temperature
2) Increase the pouring speed or increase the number or area of the inner runner to reduce the flow of metal liquid
3) Increase the pressure head of the pouring riser to prevent cut-off during pouring
Shrinkage
1、Problem description.
It can only be found by X-ray inspection. Surface shrinkage can be found by fluorescence or staining inspection. Severe cases can be found after sand blowing.
2、Cause.
(1) casting structure is unreasonable, too many hot spots or too large
2) small heat capacity of the sprue, failure to form sequential solidification, or small pressure head, lower
3) Low mold temperature, fast cooling rate, replenishment channel blockage 3.
Preventive measures.
1) improve casting organization, reduce hot spots
2) Reasonable setting of the riser, or increase the reinforcement ba