The relocation checklist we actually use on aerospace jobs

Aerospace customers do not want to hear that the machine that was cutting 30 µm TP last week now needs a week of ballbar work because a slinger caught the way covers. Here is what we tick off before the hook takes weight.

Before disconnect

  • Baseline ballbar and laser interferometer run, filed and signed.
  • Photograph the levelling pad heights and torque marks on every anchor bolt.
  • Drain and cap the coolant and hydraulic circuits. Label the caps.

On the lift

  • Lift points confirmed against the manufacturer's installation manual, not the operator's memory.
  • Slings padded at every contact with a hard edge. Way covers wrapped in shrink film, not just packing tape.
  • Spindle locked with the OEM shipping bracket. Not a bit of dowel and a prayer.

After set-down

  • Levelling to 0.02 mm/m across the bed before any electrical goes back on.
  • Warm-up run to spec, 60 minutes minimum, before geometry checks.
  • Repeat baseline ballbar and interferometer. If numbers drift more than 20% from the pre-move report, we stay on site until we know why.

Every step gets a signature and a timestamp. On MOD-adjacent work that paperwork is not overhead, it is the reason the customer sleeps.

Renishaw ballbar: reading squareness errors without over-correcting

Ballbar is the fastest way to get a machine graded end to end. It is also the fastest way to talk yourself into work that does not need doing. Squareness is where most of the over-diagnosis happens.

What the plot really means

A squareness reading of, say, 30 µm/m looks alarming until you rerun the test at half feed rate and it drops to 12 µm/m. The delta is not squareness. The delta is servo lag showing up as a geometry error on the plot.

Before we quote for a scraper and a levelling job, we always run:

  • Two feed rates at the same radius. If the number moves with feed, it is not geometry.
  • Two radii at the same feed. If reversal spikes get worse at a smaller radius, backlash and stick-slip are in play.
  • A quick axis-by-axis linearity check. Cheap to do, saves the customer the price of a full geometric alignment when the ballscrew nut is the culprit.

Ballbar reports are diagnostic. They are not a work order.

The rule we live by: no squareness correction is signed off until the number is stable across at least two feed rates and two radii. Otherwise you are chasing an artefact and the customer is paying for the chase.