The processing technology is an important link in the production of plastic moulds, which is closely related to the production quality and performance of moulds. Let’s take you to understand the heat treatment characteristics of plastic molds. China’ s leading plastic food box mould manufacturer.
Heat treatment characteristics of hardened steel plastic mould
1. for molds with complex shapes, heat treatment shall be carried out after rough machining, and then finish machining shall be carried out to ensure the minimum deformation during heat treatment. For precision molds, the deformation shall be less than 0.05%.
2. the requirements for the surface of the plastic mold cavity are very strict. Therefore, during the quenching and heating process, it is necessary to ensure that the surface of the mold cavity is not oxidized, decarburized, eroded or hot. It shall be heated in a protective atmosphere furnace or in a salt bath furnace after strict deoxidization. If it is heated in an ordinary box type resistance furnace, protective agent shall be applied to the mold cavity surface, and the heating speed shall be controlled. During cooling, a relatively mild cooling medium shall be selected to control the cooling speed, so as to avoid deformation, cracking and scrapping during quenching. Generally, hot bath quenching is preferred, and precooling quenching can also be used.
3. tempering shall be carried out in time after quenching. The tempering temperature shall be higher than the working temperature of the plastic mold. The tempering time shall be sufficient. The length depends on the plastic mold material and section size, but it shall be at least 40 ~ 60min.
Heat treatment characteristics of pre hardened steel plastic mould
1. the pre hardened steel is supplied in the pre hardened state and generally does not need heat treatment, but sometimes it is necessary to change the forging. The die blank after changing the forging must be heat treated.
2. spheroidizing annealing is usually used for pre heat treatment of pre hardened steel to eliminate forging stress, obtain uniform spherical pearlite structure, reduce hardness, improve plasticity, and improve the machinability or cold extrusion formability of die blank.
3.the pre hardening process of pre hardening steel is simple. Most of them adopt quenching and tempering treatment. Tempered sorbite structure is obtained after quenching and tempering. The temperature range of high temperature tempering is very wide, which can meet various working hardness requirements of the die. Due to the good hardenability of this kind of steel, oil cooling, air cooling or nitrate staged quenching can be used for quenchi