Injection molding machine screw material and role of each screw section

Time：2025-06-06 07:55:04 / Popularity： / Source：

I. Classification of injection molding machine screw materials

1. HPT fully hardened powder alloy screw

Using tungsten-cobalt powder alloy tool steel, it is hardened and formed by a special process. The overall hardness of inside and outside of screw is same, reaching about HRC65°. It is suitable for processing various transparent products, precision products, and special high-temperature and highly corrosive plastics such as LCP, PPS, PES, and PPA with added fibers.

injection molding machine screw materials

2. Double alloy screw

Using SACM645 and 38CrMoAlA as base material, then ion spraying tungsten carbide nickel-based alloy on the top or screw groove, surface hardness of screw is about HRC60°. It is suitable for processing various transparent products and engineering materials such as PA6 and PA66 with added fibers.

3. Electroplated screw

SACM645 and 38CrMoAlA are used as base material. After molding, outer surface is electroplated with a layer of hard chrome, nickel, titanium and other elements. Hardness is about HRC60°. Suitable for processing PC, PMMA, PET transparent materials and corrosive plastic U-PVC materials.

4. Stainless steel screw

Material is 9Cr18MoV special stainless tool steel, which is processed by overall quenching + overall hardening, and the overall hardness is about HRC55°.

5. SKD61 screw

Hitachi SKD61 material is used, and it is molded by special process. Product has good toughness and strong torsion resistance.

6. Ordinary nitrided screw

SACM645 and 38CrMoAlA are used as base material and molded by special process. Depth of nitrided layer is 0.5-0.8mm, and the overall hardness is HV980~1080°. Suitable for processing ordinary plastics such as PP, ABS, PS, AS, PVC and other ordinary plastics.

II. Injection molding machine screw segmentation description

Injection molding machine screws can generally be divided into feeding section, compression section, and homogenization section (also called metering section). (Note: Ratio of three sections of different screws is different, screw groove depth is different, and screw bottom diameter transition form is different)

1. Injection molding machine screw feeding section

This section has a fixed screw groove depth, its function is responsible for preheating and plastic solid conveying and pushing. It must be ensured that plastic begins to melt at the end of feeding section.

2. Injection molding machine screw compression section

This section is a tapered screw groove tooth depth, and its function is to melt, mix, shear, compress and pressurize plastic raw materials. Plastic will be completely dissolved in this section, and volume will be reduced. Design of compression ratio is very important.

3. Injection molding machine screw homogenization section

This section has a fixed screw groove depth. Its main functions are mixing, melt conveying, and metering. It must also provide sufficient pressure to maintain a uniform temperature of melt and stabilize flow of molten plastic.

Gud Mould Industry Co., Ltd