Unplanned machine breakdowns are one of the biggest destroyers of production efficiency, OEE, and profitability in a factory. Preventive maintenance is the systematic approach to stopping breakdowns before they happen — keeping your equipment reliable, your production running, and your costs predictable.
| Type | When Maintenance Happens | Cost Profile | Best For |
|---|---|---|---|
| Reactive (Breakdown) | After the machine fails | Low planned cost, high unplanned cost — emergency repairs, production losses | Non-critical, easily replaced equipment |
| Preventive (PM) | At scheduled intervals (time or usage-based) | Predictable, moderate cost — planned downtime is controlled | Most production equipment |
| Predictive (PdM) | When sensor data indicates approaching failure | Higher initial investment, lower total cost — only maintains what needs it | Critical, high-value equipment |
| Total Productive Maintenance (TPM) | Continuously — operators perform daily checks | Lowest long-term cost — problems caught immediately | Lean/TPM environments |
Scheduled at regular calendar intervals regardless of actual equipment usage:
Triggered by a usage milestone rather than calendar time — more accurate for equipment with variable utilization:
List every machine and critical component in your factory. Include manufacturer, model, age, and current condition. This becomes your asset register.
Not all equipment deserves the same PM investment. Classify equipment by criticality:
| Classification | Definition | PM Intensity |
|---|---|---|
| Critical (A) | Breakdown stops the entire production line or creates safety risk | High — comprehensive PM, keep spare parts |
| Important (B) | Breakdown significantly impacts production but workarounds exist | Moderate — regular PM schedule |
| Non-Critical (C) | Breakdown has minimal production impact; easily replaced | Low — run-to-failure may be acceptable |
Review the manufacturer's manual for each machine. The OEM (Original Equipment Manufacturer) specifies service intervals, lubricant types, wear part replacement schedules, and inspection checklists. This is your PM baseline.
For each piece of equipment, create a checklist of specific tasks with:
Schedule PM during planned downtime windows — shift changes, weekends, scheduled shutdowns. Avoid scheduling critical machine PM during peak production periods.
Track PM completion rates, mean time between failures (MTBF), and mean time to repair (MTTR) for each machine. Review your OEE Availability score monthly to see if your PM program is improving equipment uptime.
| Metric | Formula | Target |
|---|---|---|
| MTBF (Mean Time Between Failures) | Total uptime / Number of failures | Higher is better — track trend over time |
| MTTR (Mean Time to Repair) | Total repair time / Number of repairs | Lower is better — target <2 hrs for critical machines |
| PM Compliance Rate | PM tasks completed on time / PM tasks scheduled | Target 95%+ |
| Planned Maintenance % | Planned maintenance time / Total maintenance time | Target 70–85% planned |
| OEE Availability | Run Time / Planned Production Time | Target 90%+ for world class |
The Availability component of OEE is directly driven by your maintenance effectiveness. If your factory has an OEE Availability score of 70%, it means 30% of planned production time is being lost to equipment failures and unplanned stoppages.
A good preventive maintenance program typically raises Availability from 70–80% to 88–95% — which directly improves OEE and output without any additional capital investment in equipment.
What is the difference between preventive and predictive maintenance?
Preventive maintenance is scheduled by time or usage intervals — you maintain the machine at a set frequency regardless of its actual current condition. Predictive maintenance uses sensor data (vibration analysis, thermal imaging, oil analysis) to predict when a specific component is about to fail and only maintains it when needed. Predictive is more efficient but requires investment in sensors and data analysis capability. Most factories benefit from starting with a strong PM program before moving to predictive.
How often should I perform preventive maintenance?
It depends on the equipment and operating conditions. Start with the OEM's recommended intervals, then adjust based on your actual experience — if failures occur between PM intervals, increase frequency. If no issues are found at PM, you may be able to extend intervals. Condition changes (increased load, dusty environment, older equipment) also warrant more frequent PM.
What is autonomous maintenance in TPM?
In Total Productive Maintenance (TPM), autonomous maintenance involves training machine operators to perform basic daily maintenance tasks themselves — cleaning, lubrication, inspection, and minor adjustments. This frees maintenance technicians for more complex work and ensures problems are spotted immediately by the people working closest to the machine.
Should I use CMMS software for preventive maintenance?
For factories with 20+ machines or complex equipment, a CMMS (Computerized Maintenance Management System) dramatically improves PM compliance, record-keeping, and spare parts management. Many affordable cloud-based CMMS tools are available starting at ₹5,000–15,000/month for small factories.
Track your equipment Availability with OEE measurement:
Calculate Your OEE →Related: Production Capacity Calculator | Takt Time Calculator | Electricity Cost Calculator