Diagnosing a Problem

Auto-Index
Angle Errors

Features punched at the wrong angle, angles that drift over the course of a job, or index alarms that clear on a reset and come back. What is wearing, and how to confirm it before you take anything apart.

What you are seeing

Any of these, usually appearing gradually:

  • Angled features that are close but not right — a louvre or slot a degree or two off.
  • Angle accuracy that drifts across a long run, so the first parts pass and the last do not.
  • Index or positioning alarms that clear on a reset and return.
  • The station audibly working harder, or indexing more slowly than it used to.
  • Tooling damage in the auto-index station specifically.

What is actually wearing

An auto-index station rotates tooling to precise angles — in 0.01° increments — which is what lets you punch complex angled features without a separate key-angle tool for every orientation. That precision comes from a drive train of gears and bearings and a rotary encoder mechanism reporting position.

All of it is in constant motion, and all of it wears:

  • Gears develop backlash. The commanded angle and the delivered angle stop matching, and the error changes with direction of approach.
  • Bearings lose preload, allowing the tool to move under punching load rather than staying where it was indexed.
  • The rotary encoder mechanism loses reliable position feedback, which is where the alarm codes usually originate.

Left alone, worn auto-index stations damage tooling and ruin parts — and because the error is small at first, the scrap usually starts before anyone suspects the station.

Confirming it before you disassemble anything

Test repeatability, not just accuracy. Index the station to the same angle several times, approaching from both directions, and punch a test piece each time.

Consistent error in the same place every time points more toward calibration or programming. Error that varies between identical commands, or that changes depending on which direction the station rotated to get there, points at mechanical backlash or feedback — that is wear, and calibration will not hold.

Drift that grows over a long run is the same story: something is moving that should not be.

What a rebuild involves

An auto-index refurbishment is a full teardown, not an adjustment:

  • Complete disassembly and inspection of every internal component.
  • Replacement of worn gears, bearings and rotary mechanisms.
  • Precision rebuilding to meet or exceed OEM specification.
  • Calibration and angular accuracy testing after reassembly.
  • Full operational test before sign-off, punching at multiple angles.

Full detail on the auto-index refurbishment page.

Worth doing at the same time as sleeving

If the machine has enough hours for the auto-index stations to be worn, the standard upper turret station bores are usually showing wear too — they have taken the same number of hits. Both jobs are done on-site by the same engineers on the same visit, which means one period of downtime instead of two.

If you are seeing angle problems and holes going out of round, that is worth mentioning when you call — it changes what we would recommend.

Not sure which it is?

Tell us the machine model and what you are seeing and we will tell you straight whether this is something we fix. If it is tooling or clearance, we will say so — we would rather point you right than sell you a service you do not need.

Free estimate within 12 hours. Work is typically scheduled within 30 days, and our engineers come to your facility — the machine never ships.

Ask an Engineer 📞 1-888-686-5900