Plastic injection molds are basically divided into static molds and dynamic molds. In the injection molding machine, the sprue bushing on the side of the injection head is a static mold. The static mold generally consists of a sprue bushing, a backing plate and a template. The simple mold can also be used without a backing plate, and a thick template can be used directly. The sprue bushings are generally standard and are not recommended for special reasons unless cancelled. The use of the sprue bushing is conducive to the installation of the mold, easy to replace, without polishing. Some special mold sprue sleeves can be drilled or cut with a taper line. When the partial mold must be demoulded, the static mold release mechanism must be added. The structure of the movable mold is generally a movable formwork, a movable formwork plate, a demolding mechanism, and a die and an installed fixed plate.

      In addition to the stripping rod and the return rod, the parting mold also adds a spring to realize functions such as automatic demoulding. There are also basic structures of a mold which is indispensable for a guide post, a cooling water hole, a flow path and the like. Of course, the oblique guiding mold also has a slanting guide box, a slanting guide column and the like. When designing a mold for a product, the basic structural dimensions of the mold must first be set to prepare the material to speed up the mold manufacturing. Complex products should be drawn first, and then the size of the mold.

      The current mold is basically subjected to heat treatment to increase the hardness of the mold and increase the service life of the mold. Before the heat treatment, the template is firstly processed: drilling the guide post hole, return hole (moving mold), cavity hole, screw hole, gate hole (moving mold) cooling water hole, etc., milling the flow channel, For the cavity, some molds should also be milled with a slanted guide box. Nowadays, the template of ordinary precision molds generally uses cr12, cr12mov and some professional mold steels. The hardness of cr12 can't be too high. It often cracks when HRC is 60 degrees. The common hardness of the template is generally about 55 degrees HRC. The hardness of the core can be above HRC58. If the material is 3Cr2w8v, the hardness of the surface should be nitrided after manufacture, the hardness should be above HRC58, and the thicker the nitride layer should be.

   The gate is directly related to the beauty of the plastic part. If the gate design is not good, it is easy to produce defects. Snake flow is easily generated without any blockage. For products with high requirements, overflow and exhaust should also be designed. The ejector can be used in the overflow, and there is no overflow flash on the stencil to affect the life of the mold. There are more and more design mold software, and most of them rarely use pencils to draw mold maps.