How is a bimetallic screw barrel different from a conventional screw barrel?- Zhoushan Jiading Plastic Machinery Co., Ltd.

The screw barrel is one of the components that plays a key role in industrial processes such as plastic extrusion and injection molding. In response to the demands of handling high wear, high temperatures and corrosive plastic materials, technology has evolved to create a more durable and efficient solution - the bimetallic screw barrel.

Compared with traditional screw barrels, bimetallic screw barrels have significant differences. First of all, from a structural point of view, traditional screw barrels are usually made of a single material, usually high-quality alloy steel. A bimetallic screw barrel, on the other hand, consists of two distinct layers - an inner layer and an outer layer.

The inner layer is usually made of high wear-resistant and high-temperature-resistant materials, such as nitrided steel or high-speed tool steel, such as HPT-1. This layer is responsible for resisting the abrasive and corrosive effects of the plastic material. The outer layer is made of low-cost alloy steel, which has good strength and toughness, and provides structural support and heat conduction for the screw barrel.

This bimetallic layer is applied to conventional screw barrels through a specialized process known as bimetallic bonding or fusion. The outer layer is usually heated and softened, while the inner layer retains its original hardness. The two layers are then joined together to form a strong metallurgical bond.

The double-layer structure makes the bimetallic screw barrel superior to the traditional screw barrel in terms of performance and life. The wear-resistant inner layer resists the abrasion caused by the plastic material, thus prolonging the service life of the screw barrel. The outer layer provides structural support and efficient heat transfer, further improving processing efficiency and heat dissipation.

1. Plastic extrusion: In the plastic extrusion process, bimetallic screw barrels are widely used to produce plastic pipes, sheets, wires, profiles and other products. These products are often required to handle highly abrasive materials such as Polyvinyl Chloride (PVC), Polypropylene (PP) and Polyethylene (PE). The wear-resistant inner layer of the bimetallic screw barrel can effectively resist the friction between plastic particles and particles, prolong the service life of the screw barrel, and ensure the uniform extrusion of materials.

2. Injection molding: In the injection molding process, hot-melt plastic is injected into the mold to make various plastic products, such as plastic parts and products. For plastic materials that need to deal with high wear and corrosion resistance, such as glass fiber reinforced polyamide (PA6-GF), the bimetallic screw barrel can provide better durability and stability to ensure high quality injection molding.

3. Plastic recycling: Bimetallic screw barrels also play an important role in the plastic recycling and regeneration process. By processing waste plastics, melting them and reusing them, new plastic products are produced. Since recycled plastics may include different types of plastics, certain types of waste plastics may cause greater wear and corrosion on the screw barrel. The wear-resistant inner layer of the bimetallic screw barrel can better resist the wear of these different types of plastics on the barrel, improving the quality and sustainability of recycled plastics.

Single extruder bimetal screw and barrel
The bimetallic barrel for twin screw exruder is a kind of barrel spray a 1-3mm thick alloy coat on the barrel inner wall which has excellent corrosion resistance, abrasion resistance and high working temperature. And its useful service life is greatly improved contrast to common nitrided barrel. Bimetal has more obvious advantages when processing high calcium carbonate powder PVC mixture to enhance the abrasion life. Our company use special alloy powders being sprayed and welded on the top of screw flights, and use different alloys and welding methods for the screw of different functions.