Type 1: Easy to repair (can be quickly handled by operators / maintenance workers)
Process and quality defects: rough surface of pipes, scorched particles, streaks, uneven wall thickness, internal bubbles, etc. In most cases, these can be resolved by adjusting temperature, cooling water flow, and haul-off speed without disassembling the machine.
Minor electrical and drive faults: main motor fails to start, unstable current. Usually caused by burned heaters, unstarted lubricating oil pump, slipping drive belt, or blown fuse. The machine can be restored by replacing heater bands, tightening the belt, or resetting the emergency stop button.
Poor feeding: bridging at the hopper or foreign material blockage. Cleaning the hopper and clearing the feed opening can usually be done within half an hour.
Category 2: Moderately Repairable (requires manufacturer or professional maintenance, takes several days)
Screw wear or breakage: Causes uneven discharge and substandard products. Repair difficulty is moderately low. The screw is a conventional spare part; production can resume normally by customizing a new screw, installing and commissioning it. For example, one case was restored to normal production in 3 days. If only local thread damage occurs, alloy spray welding can also be used for repair.
Bearing or gear damage: Causes abnormal noise or vibration. Repair difficulty is moderate. The gearbox needs to be disassembled, worn parts replaced, and the meshing clearance readjusted.
Category 3: Difficult to repair (or replacement is more cost-effective than repair)
Scratches or abnormal wear on the inner wall of the barrel: Extremely difficult to repair. Since the designed service life of the barrel is usually longer than that of the screw, and the inner wall requires extremely high precision finishing, once severe scratches occur due to shaft seizure (material locking the screw) or hard foreign objects, repair is generally not feasible and the barrel is replaced directly.
Complex system failures: Extremely difficult to repair. For example, severe vibration of the extruder may result from a combination of factors such as installation level, screw clearance, and axial movement of the gearbox output shaft. In one case, the technical team of a pipe company spent two months investigating item by item from 10 aspects to completely resolve the issue.