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Servo presses are reliable machines, but when faults occur, fast diagnosis saves production time. Here are the 10 most common faults.
## 1. Servo Drive Overcurrent (OC) Fault
**Cause:** Mechanical overload, short circuit in motor winding, or acceleration ramp too steep.
**Fix:** Check motor insulation resistance (>1MΩ), verify load is within spec, increase acceleration time.
## 2. Encoder Communication Error
**Cause:** Damaged encoder cable, loose connector, or encoder failure.
**Fix:** Inspect cable for damage near flex points, reseat connectors, check encoder supply voltage (5V ±5%).
## 3. Position Deviation Alarm
**Cause:** Mechanical binding, excessive load, or servo gain too low.
**Fix:** Check for mechanical interference, verify lubrication, tune servo gain parameters.
## 4. Overtemperature — Motor
**Cause:** Continuous duty cycle too high, cooling fan failure, ambient temperature too high.
**Fix:** Check duty cycle vs motor rating, clean/replace cooling fan, verify ambient is below 40°C.
## 5. Overtemperature — Drive
**Cause:** Blocked ventilation, high switching frequency.
**Fix:** Clean drive heatsink, ensure 50mm clearance around drive.
## 6. Brake Not Releasing
**Cause:** Brake power supply fault, worn brake pads.
**Fix:** Verify 24VDC brake supply, check brake coil resistance (typically 20–50Ω).
## 7. Slide Position Drift
**Cause:** Encoder resolution insufficient, thermal expansion of frame.
**Fix:** Enable thermal compensation in CNC, check encoder coupling for slippage.
## 8. Abnormal Noise During Operation
**Cause:** Bearing wear, lubrication failure.
**Fix:** Perform vibration analysis, check lubrication levels.
## 9. Emergency Stop Will Not Reset
**Cause:** E-stop button stuck, safety relay fault.
**Fix:** Check all E-stop buttons physically, test safety relay with multimeter.
## 10. Inconsistent Part Dimensions
**Cause:** Slide parallelism error, die cushion pressure variation.
**Fix:** Check slide parallelism (should be <0.02mm/300mm), calibrate die cushion pressure.