3. In the mold manufacturing process
(1) EDM produces stress
The surface of the mold produces a white bright layer rich in electrode elements and dielectric elements, which is hard and brittle. This layer itself has cracks and stress. EDM should use a high frequency to minimize the white bright layer, must be polished and removed, and tempered, and tempered at the tempering temperature.
(2) The quality of rough forging
Some molds produce cracks only when they are produced in a few hundred pieces, and cracks develop rapidly. It is possible that only the outer dimensions are ensured during forging, and the loose defects such as dendrites, inclusions, shrinkage cavities, and bubbles in the steel are stretched and elongated along the processing to form a streamline, which is the last of the streamlines. The quenching deformation, cracking, brittle cracking during use, and failure tendency have a great influence.
(3) Grinding stress occurs during hardening of steel, friction heat is generated during grinding, softening layer and decarburization layer are generated, thermal fatigue strength is reduced, and thermal cracking and early cracking are easily caused.
(4) Cutting stress generated during final machining such as turning, milling, planing, etc., which can be eliminated by intermediate annealing.
It is believed that in the above three processes, as far as possible, step by step and careful inspection will inevitably reduce the loss caused by stress, and the output of the die-casting mold will also be improved to some extent.