What are the consequences of improper heat treatment of plastic molds

2023-07-19

The main reason for the failure of plastic molds is due to improper heat treatment processes, such as improper selection of heat treatment process parameters such as heating temperature, insulation time, cooling speed, etc. During the processing of plastic molds, cracks or deformations, surface oxidation and decarburization are mainly caused by Mold failure.
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Firstly, it is about the impact of oxidation and decarburization, mainly because mold quenching is stopped at high temperatures but cannot be strictly controlled. In addition, after decarburization on the surface of the mold, due to differences in the internal and external layers of the structure, significant structural stress appears during cooling, leading to quenching cracks.

Next is the rate of heating. Due to the high content of carbon and alloy elements in mold steel and poor thermal conductivity, the heating speed should not be too fast and should be stopped slowly to avoid deformation and cracking of the mold. When heating and quenching in an air furnace, in order to avoid oxidation and decarburization, packing maintenance heating is used. At this time, the heating rate should not be too fast, and the heat transfer should also be slow.

The above will not generate significant thermal stress and is relatively safe. If the heating speed of the mold is fast and the heat permeability is fast, a large amount of thermal stress will be generated inside and outside the mold. If the control is not good, situations such as deformation or cracks can easily occur, and preheating or slowing down the heating rate is necessary for prevention.

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