Analysis of Manufacturing Quality Requirements and Wear Solutions of Extruder Screw

Ⅰ. What are the requirements for the manufacturing quality of the extruder screw?

1. The screw used for the extruder should be made of alloy steel with small thermal deformation, wear resistance and corrosion resistance. Commonly used materials are 38CrMoAlA alloy steel or 40Cr steel, and repair parts can also be made of 45 steel.

2. The blank for the screw of the extruder should be formed by the forging method.

3. After the screw of the extruder is machined, the accuracy of the outer circle should meet the quality requirements of grade 8 (GB 180-79).

4. The coaxiality error between the working shaft surface of the extruder screw and the connecting part of the drive shaft and the outer circle of the thread of the extruder screw should not be greater than 0.01mm.

5. Roughness R of the working surface of the screw of the extruder. Value: The two sides of the thread should not be greater than 1.69m, and the bottom and outer circle of the thread should not be greater than 0.8/1m.

6. If the extruder screw elements are made of low-carbon alloy steel material, in order to improve the hardness, corrosion resistance and wear resistance of the thread working surface, the surface of the thread should be nitrided, the depth of the nitride layer is 0.3~0.6ram, and the surface hardness is 700～840HV. The brittleness is not more than grade 2.

7. 0.3MPa water pressure test should be performed on the connection of the inner hole of the extruder screw, and there should be no leakage of water for 5 minutes.

Ⅱ. The solution to the wear of the extruder screw

Two methods of extruder screw wear:

1. Each plastic has an ideal plasticizing temperature range, and the barrel processing temperature should be controlled to make it close to this temperature range. Granular plastic enters the barrel from the hopper, and will first reach the feeding section. Dry friction will inevitably occur in the feeding section. When these plastics are insufficiently heated and melt unevenly, it is easy to cause increased wear on the inner wall of the barrel and the surface of the extruder screw. Similarly, in the compression section and the homogenization section, if the molten state of the plastic is turbulent, it will also cause faster wear.

2. The speed should be adjusted properly. Because some plastics are added with reinforcing agents, such as glass fibers, minerals or other fillers. These substances tend to have much more friction on the extruder screw than the molten plastic.

When injection molding these plastics, if the high rotational speed is used, the shear force on the plastic will be increased, and at the same time, more shredded fibers will be generated accordingly. The shredded fibers contain sharp ends, which will increase the wear force to increase. When inorganic minerals slide at high speed on the surface of the extruder screw, their scraping effect is not small. So the speed should not be adjusted too high.

LESUN specializes in the production of parallel co-rotating modular screw elements, barrels and screws, ranging from Ø20mm to Ø300mm. After ten years of vigorous development, our company now has a number of advanced CNC machine tools and special processing equipment for screw manufacturing. Now our machining operations are basically intelligent and automated.

Advanced processing methods, strong technical force and sophisticated processing technology ensure that the quality and technical indicators of each production fully meet customer requirements. If necessary, welcome to consult.