How to select high-quality screws and barrels for plastic extruders

Release Time:2023-12-15 13:47


In this era of rapid development of the plastics industry, the application of plastic extruders is becoming more and more widely valued and known. The screw and barrel used in the plastic extruder is one of the core parts of the equipment, which has an important influence on the plasticization, kneading and molding of plastics. Therefore, the reasonable selection of screw structure and parameters is one of the prerequisites for improving product quality and output value. High-quality parts can better ensure normal production and improve key data such as yield and output. To meet the needs of different plastic processing. There are many kinds of screw structures, and there are three common types: gradient type (equal depth unequal distance or equal distance or unequal depth unequal distance), sudden change type, torpedo head type, etc.

So, how to choose the screw of the plastic extruder? Select high-quality screw and barrel from the following aspects:

1, according to the extruder extrusion production needs reasonable selection of barrel and screw manufacturing materials, generally choose the heat deformation is small, with wear and corrosion resistance of alloy steel. At present, the most used material in China is 38CrMoAIA alloy steel, and the material properties are optimized by performing secondary heat treatment or coating spraying on the metal surface in contact with the material. We can make certain choices from the material.

2. The screw blank chooses forging forming material to obtain better physical properties.

3. The inner wall of the barrel and the outer circle of the screw need precision machining, and the accuracy requirements should meet or exceed the 8-level accuracy requirements.

4. The outer circle of the screw thread and the transmission shaft keep concentric precision. In theory, the higher the precision, the better. However, there will always be certain errors in actual machining, which should be controlled within 10 μm.

5. If the barrel and screw need to be installed in the water cooling channel, hydraulic pressure test shall be done in advance, and there shall be no water seepage for 5 minutes under the water pressure of 0.3Mpa.

6. The gap between the inner wall of the barrel and the outer circle of the screw is strictly controlled, and it should not be too large or too small.

7. For example, some parallel twin-screw extruders adopt segmented detachable barrels. Each barrel needs to be matched directly and continuously. The center is concentric and the materials will not overflow from the joints.