What is the injection screw of a plastic machine?

Update:14 Sep 2021

The application of plastic products is closely related to our lives. Injection molding and extrusion molding are currently the most economical and energy-efficient processing methods in the field of plastic processing. Among them, the injection screw of the plastic machine is the most important key component, and different plastics have their own physical characteristics, which makes the design of the injection screw of the plastic machine different. Regarding the design of the injection screw of the plastic machine, it is generally judged by experience in the past, but the high cost does not necessarily solve the problem. Therefore, some details of the design of the injection screw of the plastic machine are worthy of our discussion and analysis.

Introduction to the injection screw of the plastic machine: The solid plastic raw material enters the screw groove from the feed hopper, and the high-speed rotation of the screw produces a shearing effect with the melt barrel, so that the plastic raw material is mixed and transported along the screw groove to make the solid plastic The raw material is heated by the electric heating plate on the outside of the melt cylinder and the shear heat generated by the screw, so that the inside of the melt cylinder is heated and melted into a melt state.

The Nitriding screw barrel  of the plastic machine can be divided into four areas according to its function:

1. Solid conveying area This section is connected with the feeding funnel, and the plastic solid particles are tightly compressed to form a solid bed. Under the shearing effect of the melt cylinder, the temperature of the plastic is gradually increased, and the plastic is conveyed forward.

2. Melting delay zone This zone is the area from the end of the solid conveying zone to the area before the melting pool is formed. Its main feature is that a thin film layer composed of melt will be formed on the surface of the solid bed and the melt cylinder, and the melt in the film layer will be subjected to the melt. The viscous force of the barrel accumulates toward the front screw groove, and the pressure formed at the end of this area is large enough to deform the solid bed, and the accumulation in the front screw groove gradually forms a melting pool.

3. The solid-melting zone is the end of the melting delay zone until the plastic is completely melted. This zone can be divided into two parts for discussion. One is plasticization, and the plasticization mainly comes from the shearing effect of the melt barrel, and the other One is the melt transfer, which transports the melt to the melting pool.

4. Melt conveying zone When all the plastics are completely melted, they will enter this zone, and end at the end of the injection screw of the plastic machine, to maintain a uniform temperature of the melt and stabilize the flow of the molten plastic.