Preventive maintenance prevents 80% of CNC downtime. Most machines need only 30 minutes daily and 2 hours weekly to stay reliable for years.
Daily (15-30 minutes)
- Inspect way oil level (top up if low)
- Drain water from air system
- Clean chips from work envelope (don’t leave overnight)
- Check coolant concentration with refractometer
- Wipe down machine exterior
- Verify spindle warm-up cycle ran (cold start risk)
- Visual inspect tool turret/changer for damage
Weekly (1-2 hours)
- Skim tramp oil from coolant (way oil floats up)
- Check coolant pH (8.5-9.5)
- Clean coolant filter / change if dirty
- Inspect way covers for damage
- Test emergency stops on all stations
- Verify backup of NC programs and parameters
- Inspect spindle taper cleanliness, blow out with air
- Check ball screw lubrication (if manual grease points)
Monthly (3-4 hours)
- Replace coolant if pH/concentration drifted
- Test machine accuracy with ball-bar (Renishaw, Heidenhain)
- Verify spindle runout (should be < 0.005mm new, < 0.015mm acceptable)
- Lubricate manual grease points per OEM schedule
- Inspect drawbar tension on tool retention
- Clean air filters in electrical cabinets
- Review chip auger condition
Quarterly
- Replace way oil if specified
- Inspect spindle bearings (vibration analysis if equipment available)
- Check axis backlash (record numbers, watch trend)
- Test machine under heavy cut (verify rigidity unchanged)
- Review parameter backups (compare to last quarter for drift)
Annually
- Full geometric calibration by service tech
- Rebuild or replace worn way wipers
- Replace gearbox oil where applicable
- Spindle bearing inspection (or rebuild plan if degrading)
- Full electrical safety inspection
Track Everything
Use a maintenance log (paper or CMMS software like Fiix, UpKeep, MaintainX). When something fails, the log tells you what changed.
Cost-Benefit
An hour of preventive maintenance prevents 4-8 hours of unplanned downtime. For a $200/hour shop rate, daily PM ROI is 8-20×.
For tools that maintain accuracy, browse our measurement tools.
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