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Three Wear Types for Screw and Barrel for Horizontal Injection Molding Machine
Screw and Barrel for Horizontal Injection Molding Machine manufacturers tell you that the screw and barrel are the key parts in the injection molding machine, which can be called the "heart". Due to their good wear resistance and high hardness, their service life is relatively long. , but they will also wear during long-term high-speed operation. Today, we will introduce the three wear types of Screw and Barrel for Horizontal Injection Molding Machine. I hope you can pay more attention to them during use.
The barrel is generally made of alloy steel or alloy steel with high compressive strength and corrosion resistance, while the screw is generally made of alloy steel with corrosion resistance and high temperature resistance. The barrel and the screw cooperate with each other to realize the crushing, melting, exhausting, compacting and conveying of raw materials.
The screw rotates at high speed in the barrel, and wear will occur over time. There are many places where wear occurs, it can occur on the screw flight, it can also occur on the surface of the barrel, or both. To reduce the degree of wear on the barrel and screw, we need to recognize three types of wear.
1. Adhesive wear
Adhesive wear occurs when the surface of the flight and the inner surface of the barrel are in contact. When there is a brief contact between the surfaces, since the two are welded together, once a rupture occurs, a high stress will inevitably be generated.
How to identify adhesion wear? The manufacturer of Screw and Barrel for Horizontal Injection Molding Machine tells you that one of the more obvious features is the burr at the end of the screw. Scratches on the surfacing material or disappearance of the surfacing material from the top of the flight also indicate adherent wear on the barrel and screw. In addition, you can also check the barrel for scratches.
2. Abrasive wear
This is a more common type of wear for Screw and Barrel for Horizontal Injection Molding Machines. Abrasive wear is very unlikely to occur if low viscosity polymers are not filled or processed. When the raw material is transported to the barrel along the screw and squeezed on the barrel wall, the raw material will wear the screw and the barrel wall due to the shearing force.
When the injection molding machine is processing resin materials containing fillers, additives, contaminants, or high-viscosity polymers, abrasive wear is more likely to occur.
The material of the raw material is relatively hard, which tends to remove material from the softer surface, so the material of the screw is generally a relatively hard and wear-resistant alloy.
Abrasive wear at the root of the screw is also caused when glass and mineral-filled resin materials are processed. This wear generally occurs in the second half of the compound channel, before the additive is wetted, and before the molten plastic is mixed.
3. Corrosion and wear
Generally, corrosion wear is formed by the gradual destruction of the material of the barrel and screw through chemical attack. Most of the atoms on the surface of the metal are oxidized, which destroys the entire surface. Once the surface of the metal is eroded, it will accelerate the wear of the barrel and screw.
When processing PVC or fluoropolymer materials, it is more prone to corrosion and wear, especially these materials will corrode iron-based components.
Generally speaking, regardless of whether the processing is polymer or metal particles, the harder the raw material to be processed, the faster the barrel and screw wear, and the original gap distance will increase. Once the gap increases, the melting efficiency of the raw material will decrease. Due to the decrease in melting efficiency, many operators will increase the speed of the screw, increase the temperature of the barrel, and increase the back pressure to compensate for the decreased melting efficiency.
Many customers hope to have a scientific method to reduce the wear and tear of Screw and Barrel for Horizontal Injection Molding Machine, but this is not an easy task, and needs to be started from the aspects of design, cutting, processing technology, and use.