Preventive vs predictive maintenance: which does a small shop need?
Preventive maintenance runs on schedules; predictive runs on sensor data and condition monitoring. The real difference, the costs, and the honest answer for small shops.
Preventive maintenance services equipment on a schedule — every 90 days, every 250 hours. Predictive maintenance services equipment when its measured condition says wear is coming — vibration signatures, oil analysis, thermal imaging. Both aim at the same thing: no surprise failures. They differ in what pulls the trigger, and in what they cost to run.
The comparison, honestly
| Preventive | Predictive | |
|---|---|---|
| Trigger | Calendar or meter hours | Condition data (vibration, oil, thermal, current) |
| Requires | A schedule and discipline | Sensors, monitoring, and analysis |
| Cost to start | Nearly zero | Real money per monitored machine |
| Risk profile | Occasionally services things early | Occasionally trusts a model too much |
| Sweet spot | Most machines in most shops | High-value, failure-critical rotating equipment |
Preventive “wastes” some maintenance by servicing on schedule rather than on need — you’ll sometimes change a filter that had a month left. Predictive eliminates that waste but replaces it with instrumentation cost and a new discipline: someone has to read and trust the data.
Where predictive genuinely earns it
Condition monitoring pays where three things stack: the machine is expensive to stop, expensive to fix, and instrumentable — big spindles, critical compressors, production-line motors. A plant with a hundred pumps has a predictive program; that’s the environment the technique was built for.
The honest answer for small shops
A 10-person shop’s maintenance problem is almost never “we lack vibration analytics.” It’s that the compressor filter has no schedule, the schedule has no owner, and the history lives in someone’s memory. Get preventive right first — it’s cheap, it’s mostly discipline, and it captures the large majority of the benefit. A PM program you actually run beats a predictive program you aspire to.
Two pragmatic upgrades that borrow predictive thinking without the sensors:
- Hour-based intervals — triggering on real usage instead of the calendar is halfway to condition-based, and any hour meter supports it
- Inspection findings as data — a photo of belt wear at every PM builds a condition record; trends become visible to human eyes for free
Both are standard behavior in maintenance software, no accelerometers required.
The one-sentence version: predictive is a scalpel for expensive rotating equipment; preventive is the seatbelt every shop should already be wearing.