Causes of die-casting mold damage:

In die-casting production, the most common form of mold damage is crack, cracking. Stress is the main cause of mold damage. Heat, mechanical, chemical, operational shocks are the source of stress, including mechanical stress and thermal stress, stress generated in:

(A) in the mold manufacturing process

1, rough forging quality problems. Some molds produced only a few hundred pieces of cracks, and cracks developed rapidly. It is possible for forging only to ensure that the size, and steel dendrites in the crystal, inclusions carbide, shrinkage, bubbles and other loose defects along the processing method is extended to form a streamline, this streamline to the future The final quenching deformation, cracking, the use of the process of brittle fracture, failure tendency greatly affected.

2, in the car, milling, planing and other final processing of the cutting stress, this stress can be eliminated by the middle annealing.

3, quenching steel grinding wear stress, grinding friction generated heat, resulting in softening layer, decarburization layer, reducing the thermal fatigue strength, easily lead to hot cracking, early cracks. The h13 steel after grinding, can be heated to 510-570 ℃, the thickness of every 25mm insulation for one hour to eliminate stress annealing.

4, EDM stress. Mold surface to produce a layer of enriched electrode elements and dielectric elements of the white layer, and hard and brittle, this layer itself will have cracks, stress. EDM processing should be used high frequency, so that the white layer to a minimum, must be removed by polishing method, and tempering treatment, tempering in the three tempering temperature.

(B) mold processing process

Improper heat treatment, will lead to mold cracking and premature scrapped, in particular, only the use of quenching and tempering, no quenching, and then surface nitriding process, in the die-casting thousands of times after the surface cracks and cracking. The stress generated during the quenching of the steel is the result of the superposition of the thermal stress during the cooling process and the stress at the time of phase change. The quenching stress is the cause of the deformation and cracking, and the solid must be tempered to eliminate the stress.

(C) in the die-casting process

Mold should be preheated to a certain temperature before production, or when the high temperature metal liquid filling when the cold, resulting in mold inside and outside the temperature gradient increases, the formation of thermal stress, so that the mold surface cracking, and even cracking. In the production process, the mold temperature rising, when the mold temperature overheating, prone to sticky mold, moving parts failure caused by mold surface damage. Should set the cooling temperature control system to keep the mold working temperature within a certain range.