What is preventive maintenance?

Preventive maintenance explained

Preventive maintenance is performed before a functional failure occurs. Typical activities include inspection, lubrication, cleaning, adjustment, replacement and proof testing at a predetermined interval.

It differs from simply doing work early. A defensible task has a reason: it controls age-related wear, detects deterioration or confirms that a protective function remains available.

Common preventive maintenance triggers

Calendar-based maintenance uses elapsed time, while usage-based maintenance responds to hours, cycles, distance or another exposure measure. Some programmes combine the two and act on whichever limit is reached first.

The right trigger depends on how the failure develops and what data can be measured reliably.

• Calendar intervals for statutory or age-related tasks
• Runtime or cycle intervals for use-related wear
• Inspection routes for observable deterioration
• Planned replacement where life is reasonably predictable

Benefits and limitations

Preventive maintenance can reduce disruptive failures, improve work preparation, support compliance and create predictable opportunities to inspect equipment. It can also waste labour and introduce faults if unnecessary work is performed too often.

The aim is not to maximise preventive work. It is to choose the most suitable response for each significant failure mode and review whether that response works.

Building a practical PM programme

Start with critical assets and credible failure modes. Define the task, method, acceptance criteria, interval and person responsible, then measure findings and breakdowns after implementation.

Treat the schedule as a controlled hypothesis. Adjust it when operating context, manufacturer guidance, failures or inspection results provide better evidence.