The basic parameters of screw of injection molding machine are generally divided into three sections, namely feeding section, compression section and homogenization section. The main function of the feeding section is to transport raw materials to the back section, so it is mainly the problem of transport capacity, with parameters (L1, H1), H1 = (0.12-0.14) d.

The main function of the compression section is to compact and melt the material and establish the pressure. The parameter compression ratio is h 1 / h 3 and L 2. The accuracy should be based on the gradient a = (h1-h3) / L2.

Homogenization section (metering section) - extrude the melted material in the compression section to the front end of the screw at constant temperature, with parameters (L3, H3), H3 = (0.05-0.07) d.