Wrote our homing SOP after a memorable Monday morning where three presses came up out of order and we crashed a transfer die. Sharing what stuck:
First rule ??never home with a die in the press if you can avoid it. Open the gate, raise the slide on a dry cycle to a safe parked position before any controlled shutdown if the schedule allows. Coming back from a power loss with a closed die is the highest-risk scenario and the one our procedure spends the most words on.
The sequence we settled on:
Start with control power only, no main contactor, no drive enable. Verify HMI is up, alarm history readable, no F-class faults latched in the drive. Acknowledge alarms one at a time and read each ??bulk-clearing hides things you need to know about.
Main contactor in, drives in standby, brake still engaged. Check DC bus voltage stabilizes at expected value (around 540V for 400V line). If it droops or wanders, stop here. We had a marginal precharge resistor that only showed up after a cold start.
Manual jog mode, low speed, brake released. Move the slide a few mm in each direction *before* requesting the home routine. Confirms the encoder reads, the brake fully released, and nothing is mechanically bound from thermal contraction overnight.
Then run the home routine and verify the position reading against a known-good reference (we paint a witness mark at TDC + clearance height). The home macro can complete cleanly and still end up off by a turn ??only the witness mark catches that.
Finally, dry-cycle once at low SPM and watch the tonnage trace. A successful home with a marginal encoder cable will look fine until the press is loaded.
Power-loss recovery isn't really about the press, it's about discipline. The procedure exists so the third-shift tech who hasn't seen this in a year does the same thing the senior guy would do.