Selection of automotive injection mold steel

Automobile injection mold steel must meet the requirements of high quality, easy processing, good polishing performance and stable heat treatment quality. In many cases, the steel is also required to have good electrical machining properties. Commonly used die steel types are pre-hardened die steel and mould base steel, and pre-hardened die steel includes integral hardened die steel and corrosion-resistant steel.

Automobile injection molds use steels with grades of 718, 618, 738, P20M, NAK80, etc., which can obtain higher wear resistance.
Pre-hardened steel is usually used in the follow cases:
  1. Large injection molds, injection molds with lower requirements for wear resistance;
  2. High strength mould base. Pre-hardened die steel is surface treated, such as nitriding.

The integral hardened steel is used as a mold or a mold insert, which hardness is 48-60HRC, can obtain better wear resistance, anti-deformation and anti-sag performance and better polishing performance. Areas such as mold cavity, runner system and parting line must have good anti-deformation and anti-sag properties to ensure product quality. Integral hardened steel usually uses 8407, 635, XW10, XW41, ASP23 and other steels.
Generally, hardened steel used in the following cases:
  1. Mass production;
  2. Plastic Injection molding with the additives of glass fiber;
  3. Integral hardened steel for optimum wear resistance and compressive strength for molds subjected to high clamping and injection pressures.

Commonly used corrosion-resistant die steels are S136H, 2316 and 2316H, etc. Usually, corrosion-resistant die steel must be used in the follow cases:
  1. The mold base is used or stored in a humid environment for a long time.
  2. The injection molding material is a heat-sensitive plastic, which will generate corrosive gas at high temperature and have corrosive effect on the mold.
  3. If the cooling channel is corroded or blocked, the cooling efficiency will be reduced, which will seriously affect the productivity of the mold.
  4. Prolonged downtime often causes corrosion on the mold surface.