TL;DR
Back-gauge drift is usually a worn ball screw, loose timing belt, or lost home reference. Check belt tension and re-home the axis before bending production parts.
What you might see
- flange dimension changes over a production run
- back-gauge axis positioning alarm
- visible belt slippage on X / R axis drive
- servo motor encoder following error
Likely causes
Worn or stretched drive belt on the X or R back-gauge axis
Ball screw backlash from wear or insufficient lubrication
Lost home reference after power interruption or E-stop
Loose coupler between servo motor and ball screw
Required tools
- Digital caliper
- Belt tension gauge
- Grease gun with machine-specified grease
- Torque wrench for coupler clamping screws
- LOTO kit
Safety first
- Lock out electrical and hydraulic power before accessing the back-gauge drive compartment.
- Do not reach into the back-gauge travel zone while the machine is energized.
Procedure
- 1
Lock out and tag out the press brake electrical and hydraulic power.
- 2
Access the back-gauge drive compartment and inspect the timing belt on each axis for cracking, fraying, or visible stretch.
- 3
Measure belt deflection by pressing with your thumb at mid-span. Replace the belt if deflection exceeds the specification in the maintenance manual.[1]
- 4
Check the ball screw for lubrication. Apply the grade of grease specified on the machine nameplate to the screw and nut through the grease fitting.
- 5
Inspect the servo motor coupler for looseness or rubber insert wear. Tighten any loose coupler clamping screws.
- 6
Restore power and run the back-gauge homing cycle from the controller menu.
- 7
Measure the gauge position against a reference stop with a digital caliper to verify accuracy.[1]
Sources
Amada Amada HG / HFE 3i Press Brake general technical documentation, Amada
Amada HG / HFE 3i press brake maintenance manual, back-gauge drive inspection and lubrication procedures (general)
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