Diagnosing Power Press Knocking Sounds: Bushing Play, Crankshaft Fatigue & Bearing Failure
Listen to Your Machine: Acoustic Diagnostics
An experienced press shop supervisor can hear machine health from across the factory floor. A sharp metallic crack at the instant of impact signals an entirely different mechanical issue than a continuous low-frequency hum during idle rotation.
Power Press Acoustic Troubleshooting Matrix
| Acoustic Signature | Operational Timing | Likely Mechanical Cause |
|---|---|---|
| Sharp Metallic "Clack" | Exactly at bottom dead center (impact) | Excessive clearance in connecting rod small-end bush or wrist pin |
| Heavy Deep "Thud" | During full stroke cycle under no load | Main crankshaft bronze sleeve bearings worn past $0.15 ext{ mm}$ tolerance |
| High-Pitched Squeal | Continuous while flywheel spins | Flywheel roller bearings starving of grease or outer race spinning in housing |
| Rhythmic Chattering | During slide return stroke | Counterbalance cylinder air pressure set too low; slide weight falling on crank |
Measuring Crankshaft Journal Runout
To pinpoint bearing wear, mount a dial indicator magnetic base to the press frame with the needle resting against the crankshaft journal. Bar the ram upward against a hydraulic jack placed on the bed. If vertical lift exceeds $0.06 ext{ mm}$ on presses up to $100 ext{ tons}$ (or $0.10 ext{ mm}$ on presses up to $300 ext{ tons}$), the phosphor-bronze bush must be scraped or replaced immediately to prevent crankshaft fracture.
Factory Reconditioning & Laser Alignment
Milap offers complete factory overhauls, crank pin regrinding, and in-situ hand scraping of phosphor-bronze bearings.
Consult Our Service Team: +91 98155 45065