Extruder Operation, Maintenance and Repair
Proper and reasonable use of the extruder can maximize its effectiveness, maintain good working condition, and extend the service life of the machine. The screw extrusion system adopts two maintenance modes: daily maintenance and periodic maintenance.
I. Maintenance and Repair of Extruders
Daily Maintenance
Daily maintenance is regular daily work that is not included in the equipment operation time, and is usually carried out during the operation of the machine. The focus is on cleaning the machine, lubricating all moving parts, tightening fasteners prone to loosening, and timely checking and adjusting motors, control instruments, working parts and circuits.
Periodic Maintenance
Generally, after the extruder has been running continuously for 2500-5000 hours and is shut down, the main components that need to be disassembled are inspected, measured and identified. Parts with wear reaching the predetermined limit are replaced, and damaged parts are repaired.
Key Maintenance Rules
- No idling is allowed to avoid damage to the screw and barrel.
- If abnormal sound occurs during the operation of the extruder, it should be stopped immediately for inspection or repair.
- Prevent metal or other debris from falling into the hopper to avoid damage to the screw and barrel. Install magnetic components at the suction port and screen materials in advance.
- Pay attention to a clean production environment, as garbage will block the filter plate material, affect product output and quality, and increase resistance.
- When the extruder needs to be stopped for a long time, anti-rust grease should be applied to the working surfaces such as the screw, shaft and machine head. Small screws should be hung in the air or placed in special wooden boxes.
- Regularly calibrate the temperature control instrument, and check the correctness of its adjustment and the sensitivity of control.
- The gearbox should use the specified lubricating oil at the proper oil level. Too little oil leads to poor lubrication; too much oil generates excess heat and accelerates oil deterioration.
- The inner wall of the cooling water pipe is easy to form scale and external corrosion. Descaling and anti-corrosion measures must be taken during maintenance.
- For the rotating drive screw, focus on checking the wear and exposure of the DC motor brushes, and regularly measure the motor insulation resistance value.
- Designate a person responsible for equipment maintenance. Keep detailed records of all maintenance and repair.
II. Operation Methods of Extruders
1. Preparations Before Starting
- Raw materials should be dried to meet the required requirements, and further drying should be carried out if necessary. Materials should be screened to remove bulk aggregates and mechanical impurities.
- Check whether the water, electricity, gas equipment and various systems are normal; ensure no leakage of water and gas flow; test auxiliary equipment at low speed without load; lubricate the sliding parts in various equipment.
- Install the head and calibrator. Assemble the head as a whole and install on the extruder. Check the cavity surface for bumps, scratches and rust, then coat the channel surface with silicone oil.
- Apply threaded parts of each block plate bolt with hot grease, then tighten the bolts and flange. Place the porous plate between the head flange.
- Adjust the head level, tighten connecting flange bolts, install the heating coil and thermocouple.
- Install and adjust the calibrator in place, check whether the main engine, setting sleeve and tractor are aligned with the center line.
- Turn on the heating power. Heat to 140 degrees first for 30-40 min, then raise to the normal production temperature. Keep for about 10 minutes to stabilize temperatures.
2. Starting
- After the thermostat is driven, tighten the head flange bolts again to eliminate the temperature difference expansion.
- Slowly rotate the screw speed adjustment knob to start the screw speed slowly, then gradually accelerate while feeding a small amount. Pay close attention to the host ammeter. The screw torque shall not exceed 65%-75% of the torque meter.
- Before the plastic profile is extruded, no one shall stand in front of the die to prevent accidents.
- When the discharge die is uniform and the plastic has ideal traction, it can be used as a good calibration standard.
3. Stopping
- Stop feeding the extruder, squeeze the internal plastic out, expose the screw, close the power cylinder and head, and stop heating.
- Turn off the power of the extruder and auxiliary equipment.
- Open the flange connection of the head, remove the head, and clean the perforated plate and various parts of the head.
- Clean the screw and barrel using shutdown material, then blow with compressed air to remove residual particles and powder.
- Pay attention to safety of heavy parts. Lifting equipment must be equipped in the extruder workshop.
