Key takeaways
Short answer: Utilization measures how much of a technician's paid time is assigned to tasks — it can look high while almost nothing gets fixed. Wrench time measures the hours actually spent doing hands-on work. The gap between them is travel, waiting for parts, hunting for information, getting permits and chasing approvals. In many plants wrench time is only 25-35% of the day, and closing that gap — not hiring more people — is the real maintenance productivity lever. See also maintenance engineer vs reliability engineer.
Utilization is the proportion of a technician's available time that is assigned or accounted for — at work, on a job, not idle on paper. It is easy to measure and easy to make look good, because a technician walking across the plant to find a part is "utilized" even though nothing is being repaired.
Wrench time (or tool time) is the share of the day actually spent with hands on the equipment doing maintenance. It is the honest productivity number, and it is usually far lower than utilization — because so much of the day is consumed by everything around the repair rather than the repair itself.
A maintenance team looks fully utilized — every technician assigned all shift. But a wrench-time study following them with a stopwatch finds the average technician spends just 30% of the day actually fixing things. The other 70% is walking to and from the store, waiting for a part that was not kitted, searching for a manual, getting a permit signed, and travelling between jobs. Hiring more technicians would just add more people at 30%. Fixing the kitting, the information access and the job planning lifted wrench time to 45% — a 50% increase in real maintenance output with the same headcount.
Utilization tells you the team is busy; wrench time tells you whether that busyness produces maintenance. A plant chasing utilization optimises the wrong number and concludes it needs more people. A plant measuring wrench time sees the 70% of the day lost to travel, waiting and searching — and realises it can get far more done by removing those barriers, no new hires required.
Plan and kit jobs before the technician starts, so parts and information are ready. Schedule to minimise travel. Make asset history and documents instantly accessible. Each barrier removed converts non-wrench time into wrench time — which is why good planning, not more headcount, is the highest-leverage maintenance productivity move.
1. Targeting utilization. The team looks busy while little gets fixed.
2. Hiring to add capacity. More people at low wrench time just adds cost.
3. No job kitting. Technicians spend the day fetching parts mid-job.
4. Inaccessible information. Searching for manuals and history burns wrench time.
Higher wrench time means faster repairs and more preventive work completed, which cuts MTTR and lifts Availability. A maintenance team that converts travel and waiting into wrench time protects OEE without growing — the productivity gain shows up directly as uptime.
See how Fabrico captures this automatically on your lines — explore OEE for manufacturing or book a demo.
Often only 25-35% of the day; the rest is travel, waiting and searching.
Utilization counts being busy; wrench time counts actually fixing things — they are very different.
Plan and kit jobs in advance, schedule to cut travel, and make information instantly accessible.
No — it usually means poor planning, kitting and information access stealing their time.
More wrench time means faster repairs and more preventive work, cutting MTTR and lifting Availability.
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