TL;DR
A knock at the crankshaft is almost always bearing wear or inadequate lubrication. Check oil pressure and oil condition before the next production run.
What you might see
- knock or rumble at top of stroke
- vibration at crankshaft housing
- oil pressure warning on crankshaft circuit
- elevated temperature at main crankshaft bearing
Likely causes
Main crankshaft bearing wear from extended service or lubrication starvation
Low lube oil pressure from a worn oil pump or blocked pickup screen
Degraded or contaminated crankshaft lubricant
Loose crankshaft eccentric or connecting rod assembly
Required tools
- Lube oil pressure gauge
- Oil sample collection kit
- LOTO kit
- Replacement oil filter element
- Aida-specified crankshaft lubricant
- Torque wrench (for eccentric bolts)
Safety first
- Stop the press immediately if you hear a new or worsening knock. Running with a failing crankshaft bearing can cause catastrophic mechanical failure.
- Lock out and tag out the main disconnect before opening any crankshaft access panel. The flywheel stores significant rotational energy.
- Insert the die block before entering the press work zone for any internal inspection.
Procedure
- 1
Stop the press immediately if the knock is new or worsening. Continued operation with a bearing knock risks catastrophic crankshaft failure.
- 2
Press the Emergency Stop and lock out the main disconnect.
- 3
Check the crankshaft lube oil level in the reservoir. Add Aida-specified oil if low.
- 4
Check the lube oil pressure gauge reading against the Aida specification. Low oil pressure confirms a lubrication circuit fault.[1]
- 5
Inspect the oil filter and pickup screen for blockage. Replace the filter if the differential pressure indicator shows restriction.[1]
- 6
Take an oil sample from the crankshaft lubrication circuit and send it for spectrographic analysis to check for bearing metal (copper, lead, tin).
- 7
If oil pressure is normal and the oil sample is clean, inspect the crankshaft eccentric bolts for looseness while the main disconnect is locked out.
- 8
If oil analysis shows bearing metal above acceptable limits, stop the press from production use and schedule a crankshaft bearing inspection with an Aida-qualified technician.
Sources
Aida NC1 Mechanical Servo Press Operation Manual, Aida Engineering
Aida NC1 Mechanical Press Operation Manual, crankshaft lubrication and bearing maintenance procedures (general)
View source
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