CNC Machine Maintenance Checklist: What to Check and When

Start of every shift

Check the way-lube and spindle-oil levels, and the coolant level and concentration. Look at the air pressure gauge if the machine uses air for the tool changer or chuck.

Warm the spindle and axes up before precision work. A short warm-up cycle brings the machine to working temperature, so the first parts aren't cut while the structure is still growing.

Glance at the alarm history on the control. A warning that appears and clears on its own, such as a lubrication pressure alarm, is often the first sign of a fault that later stops the machine.

Lubrication and coolant

Weekly: confirm lube is actually reaching the slideways, not just leaving the tank. Dry ways and a lube tank that never drops point to a blocked line or a failed pump.

Monthly: clean the coolant tank strainers and skim tramp oil. Coolant that smells or foams breeds bacteria, corrodes the machine and shortens tool life.

Axes, ways and ballscrews

Weekly: clean chips from way covers and wipers. Damaged wipers let swarf onto the ways and ballscrews, which wears them faster than anything else.

Every six months: measure backlash on each axis with a dial indicator and compare it with the last reading. A rising number is a ballscrew or support bearing wearing out, long before parts go out of tolerance.

Spindle

Weekly: listen to the spindle at speed and watch its temperature and load reading. New noise, heat or load at the same cut is an early bearing warning.

Monthly: clean the spindle taper and toolholder tapers, and check the drawbar clamping on machines with automatic tool change. A dirty taper causes runout that looks like a machine accuracy problem.

Electrical cabinet and control

Monthly: check the cabinet fans and filters. Heat is the main cause of drive and control failures, and a clogged filter can push the cabinet past its limit in an Indian summer.

Every six months: re-torque the power terminals with the machine isolated, and look for discoloured terminals or burnt smells.

Yearly, or as the manual specifies: replace the control and encoder backup batteries with the power ON, so parameters and absolute positions aren't lost.

Accuracy checks

Every six months: check level and run a circularity or ballbar test if available, or cut and measure a test part. Re-level the machine after any move or floor work.

When results drift, check thermal growth, backlash and compensation values before adjusting offsets. Offsets hide a mechanical problem; they don't fix it.

Backups and records

Keep a current backup of parameters, PMC or PLC ladder, pitch-error compensation and part programs, stored off the machine. After a battery or board failure, a backup turns days of reconstruction into a short restore.

Log every check, reading and repair with a date. Trends such as backlash creeping up or spindle temperature rising are what tell you to act before a breakdown.