admin
## Step 1: Check Power
- Main power on? Check main disconnect switch
- Control power on? Check 24V DC supply voltage
- Drive DC bus charged? Check drive status LED (should be green)
- E-stop released? Check all E-stop buttons (twist to release)
## Step 2: Check Safety Circuit
- Safety gate closed and locked?
- Light curtain clear (no obstruction)?
- Two-hand control buttons released?
- Safety relay energized? (Check safety relay LED)
If safety relay is not energized: trace the safety circuit from E-stop through all safety devices. Use PLC diagnostic screen to identify which input is open.
## Step 3: Check Drive Status
- Any active faults on drive display?
- Drive in ready state? (Not in fault or inhibit)
- Motor contactor closed? (Listen for click when enabling drive)
## Step 4: Check PLC
- PLC in RUN mode?
- Any PLC faults in diagnostic buffer?
- Press mode selector in correct position (auto/manual/setup)?
## Step 5: Check Press-Specific Conditions
- Lubrication system pressure OK?
- Counterbalance air pressure OK?
- Slide at home position (TDC)?
- Die protection sensors in correct state?
- Tonnage monitor reset after last alarm?
## If Still Not Starting
Check the press fault log (HMI → Diagnostics → Fault History). The fault log shows the exact reason the press is inhibited. This is faster than tracing the circuit manually.
mike_chen_eng
The 'press will not start' checklist is exactly what I give to new operators. One addition: check the stroke counter. Some presses have a maintenance interval counter that locks out the press when due. Operators don't always know this exists and spend 20 minutes checking everything else first.
mike_chen_eng
Great checklist. One thing I'd add from field experience: check the safety relay module itself. We had a press that passed all the individual safety checks but still wouldn't start — turned out the safety relay (Pilz PNOZ) had an internal fault that wasn't showing on the HMI. The relay's own diagnostic LED was flashing a fault code that we only noticed after pulling the panel door. Replaced the relay and it came right up.
Also worth checking: if the press has a two-hand control requirement, make sure both buttons are being pressed within the synchronization window (usually 0.5s). A worn button that's slow to make contact will cause a no-start that looks like a safety fault.