Corrosive, abrasive and high temperature resistant resin may damage the screw and barrel unconsciously. For example, some engineering materials, thermoplastic elastomers and biopolymer materials sometimes form a corrosive environment. In addition, reinforcing materials (such as glass fiber, glass ball, etc.), some fillers and additives are all abrasive.
In order to avoid affecting the production efficiency and product quality, the processor must closely monitor the hazards that these materials may cause to the equipment. In order to maintain high processing standards, it is necessary to establish a preventive maintenance program (hereinafter referred to as "PM program"). When necessary, the barrel screw should be checked and measured, and the screw should be pulled out for reinstallation or replacement, because minimal wear will also affect the product quality.
To protect the equipment from the damage of corrosive and abrasive resins, the best way is to select appropriate materials to manufacture screws and barrels. The processing cost of wear resistant barrel and screw manufactured to cope with corrosive, abrasive and high temperature resistant melts is about 3 to 4 times higher than that of standard polyolefin screw. This is because the cost of wear resistant alloys is expensive and difficult to process. However, they can provide longer service life and can be repaired at longer intervals.

1. In the process of extrusion production, because the process temperature is too low or metal foreign matters are mixed with materials in the extruder barrel, the working rotating torque of the screw will increase suddenly. This torque force exceeds the strength limit of the screw, which will cause the screw to break.
2. If there are fillers such as calcium carbonate or glass fiber in the material, the abrasion of extruder screw and extruder barrel will be aggravated.
3. The extruder screw rotates in the extruder barrel and extrudes materials. Long time friction between the screw, barrel and materials will inevitably cause wear of the barrel and screw. The inner diameter of the barrel will gradually increase and the outer diameter of the screw will gradually decrease. In this way, the gap between the screw and the barrel will gradually increase with their wear
4. Due to improper operation and unstable process temperature control, a large amount of HCI gas is often released when extruded materials are decomposed, such as PVC, which aggravates the corrosion of parts.
5. The heat treatment hardness of the working surface of the extruder screw or barrel does not reach the required value, which will accelerate the wear of the two parts.
6. Improper material selection of screw and extruder barrel will result in insufficient working strength of the two parts and shorten their working life.

The output value of extrusion directly depends on the screw speed, so precision cutting and controlling the screw speed of extruder are very important. The measured and flashed crown rod speed shall be accurate to 0.1 r/min at least, and 0.1 r/min or less at best. In other words, the sensitivity and resolution of screw speed measurement should be 0.1 r/min or very good. Assuming the full range is 200r/min, the measurement sensitivity is 0.05% of the full range. When the extruder operates at low speed, the measurement of rotating speed is particularly important. For example, if the extruder operates at 5r/min and the resolution of screw speed is 1r/min. When the screw speed changes within 20%, there will be no change in measurement control data. When the resolution is 0.1 r/min and the screw speed is changed within%, the measured flash value of the screw will not change.
Another major question that needs to be considered is the speed scheduling of the extruder and the tractor. The speed dispatching accuracy of a typical brush type current appropriate motor with speed measurement response dispatching is 1% of the full scale. Assuming that the maximum speed is 100r/min, when the screw speed is 10r/min, the change value can reach plus or minus 1r/min, that is, plus or minus 10%, and the total change can reach 20%. This is not allowed for most extrusion processes. Brushless DC motor or digital pulse brush DC motor with digital driving skills can greatly improve the speed regulation accuracy, which can reach 0.01% of the full range or very good. That is to say, even at a very low speed, this driving method can ensure that the screw speed is very stable.
Obviously, the dispatching of traction speed has the same main meaning. Assuming that the output value of extrusion is stable and the traction speed is changing, the scale of finished products will also change. Therefore, it is recommended that the speed scheduling accuracy of the extruder and the traction device should reach 0.01% or higher of the full scale. Because the digital drive is not expensive compared with the old brush DC motor with or without tachometer in price, there is no reason not to use the digital drive device.

The screw needs to be cooled when extruding materials, mainly to ensure smooth production and prevent materials from decomposing due to too high plasticizing temperature. For example, cooling in the feeding section of the screw is to prevent the temperature of this section of the screw from being too high, and to prevent the materials from being attached to the screw thread groove due to the high temperature and rotating with the screw, which affects the forward movement of the material delivery, resulting in the failure of normal production due to insufficient material supply. The homogenizing section of the screw is cooled because the molten materials in this section generate more heat due to greater extrusion, friction and shearing, and the temperature rises faster. In order to prevent material decomposition, cooling is required.