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1 Reason: The drive shaft inside the injection molding machine’s shot platen is too long, the internal spline hole is too shallow, or the fit between the internal spline and the motor shaft’s spline is too tight; forced installation of the motor results in damage to the bearings in the motor housing, causing difficulty in the motor’s rotation and abnormal internal leakage. Solution: Remove the motor and check whether there are obvious indentations at the cutting start position of the motor shaft spline. If there are indentations, it indicates that the drive shaft inside the two injection plates is too long. Based on actual conditions, shorten the drive shaft of the plastic molding machine; add a chamfer at the front end of the spline in the drive shaft. It is also possible to thicken the second injection plate, or use shims of appropriate thickness at the five mounting holes on the front surface of the motor, thereby lifting the motor a certain distance away from the second injection plate. Modify the size of the spline hole in the plastic molding machine’s drive shaft until it matches the motor’s spline. 2 Cause: The plain thrust bearings and tapered bearings on the drive shaft inside the second platen of the plastic injection molding machine are severely worn, resulting in excessive load on the motor and abnormal internal leakage. Solution: Replace the damaged plain thrust bearings and tapered bearings on the plastic machine’s drive shaft. 3. The loosening of the lock nut on the plastic machine’s drive shaft caused the shaft to shift axially, resulting in damage to the bearings in the motor housing due to impact; this led to difficulties in rotating the motor and abnormal internal leakage. Solution: Remove the motor from the plastic molding machine, tighten the lock nut on the machine’s drive shaft, and then install a new motor. 4 Reasons: The oil is too dirty, foreign objects have entered the motor, the internal components of the motor are damaged, resulting in severe internal leakage in the motor. Solution: Filter or replace the system oil. 5 reasons: The motor operates at a high speed or the system oil temperature is too high (the system oil temperature should generally be below 80°C); the oil has deteriorated; the internal components of the motor are worn out, resulting in severe internal leakage in the motor. Solution: Inject forced cooling oil into the motor housing, and increase or upgrade the cooler to lower the system oil temperature. Note: First, use an air gun to check and confirm whether the oil return pipe of the motor housing is blocked. Then remove the motor and run it without a load; if the internal leakage remains high (the internal leakage is lower under no-load conditions), it indicates that there is an abnormality inside the motor. Additionally, if the motor experiences severe internal leakage due to cracks in individual cylinders, the motor should be removed and rotated with the oil pipes attached to check whether the internal leakage is normal. Sometimes, the internal leakage in such cases remains low, in which case the motor needs to be disassembled to inspect its internal components.