What is preventive maintenance? Definition, examples, and a starter program

Preventive maintenance (PM) is servicing equipment on a planned schedule — time-based, usage-based, or both — so wear gets handled before it becomes failure. The contrast is reactive maintenance: fixing things after they break, at the worst possible time, at emergency prices.

What counts as preventive maintenance

Anything recurring and scheduled: lubrication, filter and fluid changes, blade replacement and sharpening, belt inspection and tensioning, calibration, cleaning that affects function (glycol systems, dust collection), and formal inspections. The defining feature isn’t the task — it’s the trigger. If the trigger is a calendar or an hour meter, it’s preventive. If the trigger is a noise, it’s already reactive.

Examples by machine type

• Bandsaw / cold saw: blade replacement every 60–90 days of use; guide bearing check monthly
• Air compressor: drain moisture weekly; filter change monthly-to-quarterly; oil per hours
• Forklift: daily operator walkaround; hydraulic and brake inspection semi-annually
• CNC machinery: way lube and coolant checks weekly; spindle and filter service per hours
• Welders: consumable inspection weekly; ground and lead check monthly
• Vehicles & heavy equipment: oil, filters, greasing by engine hours — the classic hour-based PM

Intervals come from the manual first, then get adjusted to your duty cycle — a compressor feeding two plasma tables is not on the manual’s schedule.

Why shops skip it (and why that’s expensive)

PM loses the daily argument because it’s deferrable: nothing bad happens today if you skip the filter. The costs arrive later, bundled — unplanned downtime mid-job, rush-shipped parts, overtime, and the machine that ages out years early. Reactive-heavy shops also can’t quote lead times honestly, because their capacity has a random failure schedule built in.

The economics are lopsided: a PM task costs minutes and a part; the failure it prevents costs a day and a customer.

Starting a program this week

1. List the machines that stop work when they stop. Not everything — the critical ten.
2. Write one recurring task per machine with an interval from the manual. Our free PM schedule template is exactly this list.
3. Put next-due dates on a surface people see. A schedule nobody reads is a wish.
4. Log completions — date, who, parts — so the schedule builds a history.
5. After a quarter, adjust intervals based on what you found: belts always fine? Stretch it. Filters always packed? Tighten it.

The failure mode of paper programs is step 3 — the schedule that lives in a binder chases no one. That’s the specific thing maintenance software fixes: due work surfaces itself on a dashboard, overdue work escalates, and completions write the log automatically.

The one-sentence version: preventive maintenance is choosing when your machines get attention — instead of letting them choose.