Which Quality Problem Can Occur With Powder Metal Parts?

Common defects in powdered metal parts and their causes. What are the common defects in powdered metal parts and their causes?
The common defects and their causes of compaction are as follows:
Ⅰ Uneven density, caused by:
1) The compression ratio of each part is inconsistent;
2) The low smoothness of the mold increases friction resistance;
3) Insufficient lubrication;
4) The size of the parts is unreasonable (the length to diameter ratio is too large, the length to wall thickness ratio is too large...);
5) The suppression method is incorrect

Ⅱ Cracks can occur due to:
1) Uneven density;
2) Poor powder formability and large elastic aftereffect of pressed blanks;
3) The demolding method is incorrect;
4) Poor mold rigidity;
5) The mold has a taper angle.
Ⅲ The reasons for falling edges and corners include:
1) Poor powder formability;
2) The compact density is low.
Ⅳ Surface scratches, caused by:
1) Scratches on the surface of the mold;
2) Appearance of mold tumor