
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:
- Large injection molds, injection molds with lower requirements for wear resistance;
- 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:
- Mass production;
- Plastic Injection molding with the additives of glass fiber;
- 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:
- The mold base is used or stored in a humid environment for a long time.
- The injection molding material is a heat-sensitive plastic, which will generate corrosive gas at high temperature and have corrosive effect on the mold.
- If the cooling channel is corroded or blocked, the cooling efficiency will be reduced, which will seriously affect the productivity of the mold.
- Prolonged downtime often causes corrosion on the mold surface.