MTTR

MTTR (mean time to repair) measures how fast maintenance responds: on average, how long a machine stays down per breakdown. Together with MTBF, it shows whether the problem is the machine failing often or the team taking long to fix it.

How it works

The formula is total repair time ÷ number of failures. The clock starts when the machine stops and ends when it makes a good part again, so it includes waiting for the technician, diagnosing, getting parts and testing. Splitting these steps reveals where the delay is; often it is not the repair, but the late alert or the part that is not in stock.

Practical example

A machining center had 4 failures in a month, totaling 10 hours down. MTTR = 2 h 30 min. With an automatic WhatsApp alert to the technician when the alarm fires and a kit of critical spares in the storeroom, MTTR fell to 1 h 10 min.

Common mistakes

• Starting the clock only when the technician arrives, hiding the waiting time.
• Not recording the cause, which prevents tackling repeat failures.
• Lowering MTTR with quick fixes that later lower MTBF.