Asset criticality matrix: stop giving every machine the same PM
Ask four questions about what happens when an asset fails: can someone get hurt, does anything leave the building, does the line stop, does bad product ship? Score each from 1 to 5, add them to get a number out of 20, and let that number set PM effort, spares and which job goes first.
Price is not scored, so a costly press with a twin can rank below a cheap conveyor that everything runs through.
Why even PM fails
When every asset gets a preventive maintenance task and every task gets about the same attention, the roof fan with a spare in the crib is inspected as faithfully as the machine that feeds three lines. When two things break at once, the order comes from whoever called first or whoever outranks whom. The crew is busy all week and still behind on the machines that make the money.
Emergency medicine solved the same problem more than two centuries ago by treating the wounded in order of how badly they were hurt, not by rank. Every emergency room works that way now. A work order queue can borrow the idea: rank by consequence of failure.
The four questions
Ask them about the failure, not the asset. What happens when it fails with no warning?
| # | Ask | Think about |
|---|---|---|
| 1 | Can someone get hurt? | Stored energy, pressure, a guard that comes off. |
| 2 | Does anything leave the building that should not? | A spill, a release, an emissions problem. |
| 3 | Does the line stop? | Or is there a backup, a spare, a bypass? |
| 4 | Does bad product ship? | Slow drift that turns into scrap or a customer complaint. |
What each score means
Agree on the anchors before you start and score as a group of maintenance, operations and safety. Without anchors every asset becomes a 4 or a 5.
| Score | 1. Safety | 2. Environment | 3. Production | 4. Quality |
|---|---|---|---|---|
| 1 | No realistic way to cause injury | Nothing can escape | A twin or spare takes over at once | No effect on product |
| 2 | Minor injury, first aid only | Small leak, contained and cleaned up in the shift | Standby or bypass, only a short slowdown | Slight drift, caught by routine checks |
| 3 | Injury that costs lost time | Spill beyond the bund, reported inside the company | Output drops; the spare takes hours to fit | Some scrap or rework in-house |
| 4 | Serious injury possible (stored energy, pressure, guard removed) | Reportable release or permit limit exceeded | One line stops for hours to a day | Out-of-spec product could reach the customer unless inspection catches it |
| 5 | Fatality or several serious injuries possible | Major release, or repeated emissions breach | Plant or several lines stop; no backup, long lead time | Defective product likely to ship; complaint or recall risk |
Bands and plans
Add the four scores for a total out of 20. Many sites add one override: if Safety or Environment scores 4 or 5, the asset is Critical whatever the total.
| Total | Band | What the asset gets |
|---|---|---|
| 16 to 20 | Critical | Condition monitoring plus frequent PM. Spares on site. Root-cause review after every failure. |
| 12 to 15 | High | Full PM, critical spares held, periodic condition checks. |
| 8 to 11 | Medium | Basic PM at the standard interval. Repair on condition. |
| 4 to 7 | Low | Run to failure. Keep a spare on the shelf and do minimal checks. |
Worked example
An illustrative list for a small plant. The numbers are examples, not benchmarks.
| Asset | Safety | Env. | Production | Quality | Total /20 | Band |
|---|---|---|---|---|---|---|
| Ammonia compressor | 5 | 5 | 4 | 2 | 16 | Critical |
| Filler feeding three lines | 3 | 2 | 5 | 4 | 14 | High |
| Boiler feed pump | 4 | 3 | 5 | 2 | 14 | Critical |
| Main bottleneck conveyor | 2 | 2 | 5 | 4 | 13 | High |
| Twin hydraulic press (one of two) | 3 | 2 | 2 | 3 | 10 | Medium |
| Plant manager's favourite lathe | 2 | 1 | 1 | 2 | 6 | Low |
| Roof exhaust fan (spare in crib) | 1 | 1 | 1 | 1 | 4 | Low |
The conveyor and the filler outrank the costly press because they have no backup. The roof fan and the favourite lathe score low, so they get a run-to-failure plan and a shelf spare. The ammonia compressor is Critical on safety and environment alone.
Quick test: where do the hours go?
Pull the last three months of PM labour hours and sort the assets by score. Add up the hours for the top third and the bottom third. If the bottom third uses about as many hours as the top third, the PM budget is spread evenly instead of by risk. Move hours from the low scorers to the high scorers, then repeat the check after a quarter.
Putting it into the CMMS
- Week 1: pick the scope, usually the top 50 to 100 assets by process importance.
- Week 2: score them in a short workshop using the anchors above.
- Week 3: add Score and Band as fields on the asset so they show on every work order.
- Week 4: give each band a standard plan.
- Weeks 5 to 12: cut tasks on Low assets, add condition checks on Critical ones, then repeat the hours check.
Dispatch rule: two jobs at once, the higher score goes first. Equal scores, the asset with no backup goes first. Safety or Environment of 4 or 5 always goes first.
Common mistakes
- Scoring by purchase price. Price is not one of the four questions.
- Scoring by who shouts loudest or who owns the machine.
- Giving everything a 4 or 5. Use the anchors and expect a spread.
- Never revisiting the score after a spare, a bypass or a process change.
- Keeping the matrix on one laptop instead of in the work order system.
Free matrix and CSV template
The Rotec AI tool has an interactive matrix: add assets, score them with a dropdown, see the band, enter PM hours and run the top-third versus bottom-third test. Your list stays in your browser. You can export and import CSV.
Open the PM criticality matrix · Download the CSV template
Questions
What is an asset criticality matrix?
A table that scores each asset on what happens when it fails. Four questions are scored 1 to 5 (safety, environment, production, quality) and added to give a number out of 20. The score sets PM effort, spares and the order of work.
Should the purchase price be part of the score?
No. Price is deliberately left out. An expensive machine with a twin beside it can score lower than a cheap conveyor that every other machine depends on.
How do I use the score on the shop floor?
Store the total and band as fields on the asset in your maintenance system (CMMS) so they appear on every work order. When two jobs arrive at once, the higher score goes first.
What should I do with a low-scoring asset?
Give it a run-to-failure plan: minimal checks and a spare on the shelf. That frees labour hours for the assets that can hurt people, leave the building as waste or stop the plant.
How do I know if my PM budget is spread too evenly?
Take three months of PM labour hours and sort the assets by score. If the bottom third uses about as many hours as the top third, the effort is spread evenly rather than by risk.
Is this the same as a full FMEA or criticality analysis?
No. It is a fast first screen that ranks whole assets. A detailed failure-mode analysis can follow for the Critical assets.
Related: Lubrication guides · Condition monitoring · Bearing failure modes · Plan the PM window · Open the PM tool