Three-screw extruder: the cause of screw wear, and its maintenance work!
Reasons for the screw wear of the three-screw extruder:
If you find that the screw wear is very serious in the process of using the three-screw extruder, it may be because of the following reasons, let's take a look!
1. The processing temperature of the barrel
Every kind of plastic has an ideal plasticizing processing temperature range, and the processing temperature of the barrel should be controlled to make it close to this temperature range. When the granular plastic enters the barrel from the hopper, it will first reach the feeding section, and dry friction will inevitably occur in the feeding section. When these plastics are not heated enough and melt unevenly, it is easy to cause increased wear on the inner wall of the barrel and the surface of the screw.
2. Friction between material and screw
The screw rotates in the barrel, and the friction between the material and the two causes the working surface of the screw and the barrel to wear gradually: the diameter of the screw gradually decreases, and the diameter of the inner hole of the barrel gradually increases. In this way, the matching diameter gap between the screw and the barrel increases a little bit with the gradual wear of the two. However, since the resistance of the head and the splitter plate in front of the barrel has not changed, this increases the leakage flow when the extruded material advances.
3. The speed should be adjusted properly
Because some plastics are added with reinforcements, such as glass fibers, minerals or other fillers. These substances tend to be much more abrasive to metallic materials than molten plastic. When injecting these plastics, if they are molded at a high speed, while increasing the shear force on the plastic, it will also make the reinforcement correspondingly produce more shredded fibers. The shredded fibers contain sharp ends, causing wear and tear. The force is greatly increased.
4. The material contains calcium carbonate or glass fiber
If there are fillers such as calcium carbonate and glass fiber in the material, the wear of the screw and barrel can be accelerated. Because the material is not plasticized evenly, or there is metal foreign matter mixed into the material, the screw rotation torque suddenly increases, and this torque exceeds the strength limit of the screw, causing the screw to break. This is an unconventional accident damage.
Maintenance of three-screw extruder:
When using a three-screw extruder, it is necessary not only to use the correct operation method, but also to maintain it according to the regulations. Let's take a look at its maintenance work:
1. Since the electrical control system of the three-screw extruder has high requirements on ambient temperature and dust prevention, the electrical system should be isolated from the production site, and ventilation or ventilation fans should be installed. It is recommended to place the electrical control cabinet in a simple room Inside, keep the room clean and ventilated so that the indoor temperature does not exceed 40°C.
2. The three-screw extruder is not allowed to run empty to avoid linting of the screw and machine. When starting the main engine, start at a low speed. After starting the main engine, check whether there is any abnormal noise, and then slowly increase the main engine speed to within the allowable range of the process. When the new machine is running in, the current load should be 60-70%, and the current in normal use should not exceed about 90%. Note: If there is abnormal sound when the extruder is running, it should be stopped immediately for inspection or repair.
3. Turn on the oil pump first when starting up, and then turn off the oil pump after shutting down; the water pump remains in working condition during the whole production process, and the operation of the water pump cannot be stopped, so as to avoid the decomposition and carbonization of the material in the barrel due to the temperature rise of the barrel; the asbestos wind cover of the main motor fan needs to be Clean it frequently to avoid excessive dust adhesion to block the windshield, resulting in insufficient heat dissipation of the motor and tripping due to overheating.
4. Clean up the dirt, tools and sundries on the surface of the unit in time. Strictly prevent metal or other sundries from falling into the hopper, so as not to damage the screw and barrel. In order to prevent iron debris from entering the barrel, a magnetic component or a magnetic frame can be installed at the feeding port of the barrel when the material enters the barrel. To prevent debris from falling into the barrel, the material must be screened in advance.
The above is what TENGDA Plastic Extruder Machine Manufacturers introduced to you about the reasons for the screw wear of the three-screw extruder and its maintenance work. I hope this article can help you better understand this industry.
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