admin
Abnormal noise from a servo press is always a warning sign. Identifying the source quickly prevents minor issues from becoming major failures.
## Noise Diagnosis Framework
First characterize the noise:
- **When does it occur?** Approach, forming, return, or all stroke?
- **What frequency?** Once per stroke, continuous, or random?
- **Where is it coming from?** Use a stethoscope or vibration analyzer to localize.
- **Has anything changed recently?** New die, maintenance, parameter change?
## Common Noise Sources
### Knocking at BDC
**Cause:** Excessive slide-to-gib clearance, worn main bearings, or loose bolster.
**Diagnosis:** Measure gib clearance. Check bearing play with dial indicator.
**Fix:** Adjust gibs, replace bearings if worn beyond limit.
### High-Pitched Whine from Servo Motor
**Cause:** Servo gain too high causing oscillation, or bearing wear.
**Diagnosis:** Check for position oscillation on drive monitor. Measure motor vibration.
**Fix:** Reduce velocity loop gain by 10-20%. Replace bearings if vibration >4.5 mm/s RMS.
### Grinding Noise
**Cause:** Lubrication failure — metal-to-metal contact.
**Diagnosis:** Check lubrication system pressure and flow. Inspect oil for metal particles.
**Fix:** Restore lubrication immediately. Inspect contact surfaces for damage.
### Clunking During Direction Reversal
**Cause:** Backlash in drive train, loose coupling, or worn gear teeth.
**Diagnosis:** Check coupling tightness. Measure backlash at slide.
**Fix:** Tighten coupling. Replace worn gears.
### Air Noise
**Cause:** Counterbalance cylinder seal leak, or air valve malfunction.
**Diagnosis:** Listen for hissing. Check counterbalance pressure gauge for drift.
**Fix:** Replace cylinder seals or air valve.
## Using Vibration Analysis
A vibration analyzer with FFT capability can identify bearing defects before they become audible. Key frequencies to monitor:
- Main shaft rotation frequency
- Bearing defect frequencies (BPFO, BPFI, BSF)
- Gear mesh frequency
Baseline measurements taken during commissioning make trend analysis much more effective.