Tue Apr 25 14:57:13 CST 2023
Steel used for plastic mould material
Mould material refers to the steel grades used for plastic mould materials in China, which can be classified according to the steel characteristics and the heat treatment state when used.
The so-called pre-hardened steel is supplied having been pre-treated and brought to the hardness of the mould use state. The characteristics of this type of steel is in the state of hardness 30 ~ 40HRC can be directly shaped turning, drilling, milling, engraving, fine filing and other items of processing, finishing can be delivered directly after use, which completely avoid the impact of heat treatment deformation, thus ensuring the accuracy of the mold manufacturing.
China in recent years the development of pre-hardening plastic mold steel, most of them are based on medium carbon steel, adding the right amount of chromium, manganese, nickel, molybdenum, vanadium and other alloying elements made. In order to solve the problem of difficult cutting under higher hardness, by adding sulfur, calcium, lead, selenium and other elements to the steel to improve the cutting performance, thus making easy to cut pre-hardened steel. Some pre-hardened steels can be nitrided after the mould has been machined and shaped, so that the surface hardness and wear resistance of the mould can be significantly increased without reducing the hardness of the substrate.
Steel is precipitation hardening stainless steel, hardness of 32 ~ 35HRC when cutting, the steel and then by 460 ~ 480 ℃ after aging treatment, can obtain a better overall mechanical properties.
The common feature of such steel is the low carbon content, high alloy degree, by high temperature quenching (solution treatment), the steel is in a soft state, the organization of a single supersaturated solid solution. However, when this solid solution is aged, i.e. heated to a lower temperature and held for a period of time, small, diffuse metal compounds precipitate out of the solid solution, resulting in strengthening and hardening of the steel. Moreover, this strengthening process causes very little change in size and shape. Therefore, when using this type of steel to manufacture plastic moulds, the mechanical forming process of the mould can be carried out after the solid solution treatment, and then through the ageing treatment, so that the mould can obtain the strength and hardness in use, which effectively ensures the accuracy of the final size and shape of the mould.
In addition, this type of steel is often vacuum smelted or electroslag remelted, and the steel has a high degree of purity, so the mirror polishing properties and photo-etching properties are good. This type of steel can also be surface treated by chromium plating, nitriding, ion beam enhanced deposition and other surface treatment methods to improve wear resistance and corrosion resistance.