5. Measures to the displacement and size over tolerance: for improper adjustment of the mold, we can continue to adjust the mold to eliminate it; for the size over tolerance caused by mold wear, we need to replace the new mold. For the replacement of the old molds, we can repair and reuse them. A stamping die includes cutting mold, cutting knife board and die, their repairing and reusing are as follows:
5.1 Repairing and reusing of cutting mold: the quality of cutting mold determines the quality of the material and the steel balls. Repairing of cutting mold includes grinding the working face and bore of cutting mold. The grinding amount is 0.5mm. Since the length of the cutting mold is decided, wearing 0.5mm should add a gasket with thickness of 0.5mm to supplement.
5.2 Repairing and reusing of cutting knife board: same as cutting mold, the quality of cutting knife board determines the quality of the material and steel balls. Repairing and reusing of cutting knife board includes grinding the working face and edge part of cutting knife board.
5.3 Repairing and reusing of die depends on repairing its work part. From the test data, we sum up the best fatigue layer thickness is 0.5mm.
6. Measures to cracks: As the material crack is the quality problem of raw material, the raw materials with cracks can’t be used to upset steel balls blanks. Upsetting cracks is one of the common quality problems when punching steel balls blanks. Material hardness is too high or upsetting ratio is inappropriate may both cause upsetting cracks. The crack caused by the material of high hardness, we can pickle bar material to solve it; as for upsetting cracks caused by too large upsetting ratio and too long material, we can properly increase bar diameter or reduce the length of the material to eliminate.