The choice of mold materials Before we talk about mold materials, we first need to understand some basic information about the mold, first of all this is the classification of the mold, the general mold from the service life is divided into five categories, a class of more than 1 million times, with the second class, 500,000 - 1 million times, the third class 300,000 - -500,000 times, the fourth class 100,000 - 300,000 times, the fifth class 100,000 times or less, one or two molds need to use hardness in HRC50 or so can be heat-treated steel, otherwise easy to wear, injection molding products are easy to super poor. Steel should not only have good heat treatment performance, but also have good heat treatment performance in the high hardness state, cutting performance, of course, there are other considerations. Since I rarely encounter domestic plastic mold steel, so I can only introduce the Pearl River Delta commonly used imported materials. Usually Sweden's 8407, S136, the United States 420, H13, Europe's 2316, 2344, 083 or Japan's SKD61, DC53 (the original metal mold material, used in special circumstances) belong to the steel. In addition, injection molding raw materials and added fillers, especially glass fiber wear on the mold, has a great impact on the choice.

Some plastics can cause acid corrosion, and some have added enhancers or other modifiers, such as glass fiber, which seriously damage the shape, so comprehensive attention should be paid to the selection of materials. For highly corrosive plastics, generally choose S136, 2316, 420, for slightly corrosive plastics, in addition to S136, 2316, 420, SKD61, NAK80, PAK90, 718M. Strong acid plastics: PVC, POM, PBT Weak acid plastics: PC, PP, PMMA, PA

The requirement of product appearance also has a great influence on the choice of mold material. For transparent parts and products whose surface needs mirror polishing, S136, 2316, 718S, NAK80, PAK90, 420 materials and molds can be used. For high transparency, choose S136, then 420.

The above is about meeting product requirements, but as a designer, if you only consider them, not only will you not be a good designer, your work and the cost of the tooling you use may also be in question. re. The most important thing is to consider the price, take S136 and 2316 to make a comparison, the difference between 55-60 yuan a kilogram, choose the wrong one, the boss either do not take orders or go bankrupt.

There are many pre-hardened tertiary mold materials, these grades are: S136H, 2316H, 718H, 083H, hardness HB270 ----340, fourth and fifth grade for P20, 718, 738, 618, 2311, 2711. You can use S50C, 45# steel, that is, directly on the mold base for the cavity. (Bulletproof glass adhesive)

Mold shrinkage of common plastic