What are the common defects and causes of blank pressing?

Common blank defects and causes are as follows:

(1) density is not uniform.

The reasons are: 1) the parts compression ratio is not consistent; 2) mold finish is low, increased friction resistance; 3) lubrication inadequate; 4) parts size is unreasonable (long diameter ratio is too large, long wall thickness ratio is too big...) 5) to suppress the wrong way.

(2) crack.

Causes: 1) uneven density; 2) powder forming poor, blank elastic aftereffect high pressure; 3) release the wrong way; 4) die poor rigidity; 5) die taper.

(3) drop off angle.

The reasons are: 1) the powder forming property is poor; 2) the blank density is low.

(4) surface scratch.

The reasons are: 1) die surface scratch; 2) there die.