The Causes of Extruder Screw Abrasion and the Methods of Reducing Abrasion

The extruder screw is operated under high pressure, high temperature, high mechanical torque and high friction environment for a long time. Generally, the extruder screw has undergone surface nitriding treatment to improve the surface hardness, that is, to improve the wear resistance.

However, if the cause of wear is neglected and the wear is not minimized, it will inevitably greatly reduce the working life of the extruder screw for sale.

Ⅰ. Reasons for abrasion of extruder screw and methods to reduce abrasion

1. The screw speed of the extruder should be adjusted properly, because some plastics are added with strengthening agents, such as glass fiber, minerals or other fillers. The frictional force of these substances on metal materials is often much greater than that of molten plastics.

When injecting these plastics, if a high speed is used, while increasing the shearing force to the plastic, it will also make the reinforcement correspondingly produce more torn fibers. The shredded fibers contain sharp ends, which greatly increase the abrasion force. When inorganic minerals slide at high speed on the metal surface, their scraping effect is not small. Therefore, the speed should not be adjusted too high.

2. Each plastic raw material has an ideal plasticizing processing temperature range, so the processing temperature of the barrel should be controlled to make it close to this temperature range.

Granular plastic enters the barrel from the hopper and first reaches the feeding section. Dry friction is bound to occur in the feeding section. When these plastics are not heated and melted unevenly, it is easy to cause the inner wall of the barrel and the outer surface of the extruder screw to increase. Similarly, in the compression section and the homogenization section, if the melting of the plastic is disordered and uneven, it will also cause increased wear.

Ⅱ. If the screw assembly gap in the extruder barrel is too large, what will be influenced?

1. The output of the products produced by the extruder is unstable or the output decreases.

2. If the working surface gap between the screw and the extruder barrel is too large, the amount of reflux material generated when the screw is plasticized and the melt is pushed forward is large. The result of this is that part of the molten material stays in the barrel for a long time and becomes yellow, which causes discoloration or focal spots on the surface of the product.

3. If the gap is too large, the pressure of the extruded melt will be unstable, resulting in a large error in the geometric shape and size of the product's cross-section.

4. Because the gap is too large, the melt flow rate pushed out by the screw and barrel of the extruder is also unstable, which makes the surface of the product prone to horizontal wrinkles.

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