Mean Time To Repair (MTTR) is one of the important metrics to improve OEE and reduce length of breakdowns. Ultimate goal is to have zero breakdowns.

But breakdown has happened, so how can we return equipment back to production ASAP?

Two things required:

  • strong skill set (mechanical, electrical and controls, pneumatic and hydraulic etc.);
  • spare parts availability (interchangeability of existing stock)

Skill set or lack of knowledge

Skill improvement needs to be done based on Breakdown Analyses, which can include following lean tools:

If one of the causes was “took a long time to repair” and spare parts were available, particular skill needs to be improved, for example:

Equipment was down for extended periods of time due to mechanics were troubleshooting “top sealing assembly”. They had to alter temperature, sealing pressure and dwell time in order to eliminate product leakage.

From example above we can clearly identify that set points, principle of operation etc. were not clearly understood by maintenance crew.

Next steps – implement training and share with entire team, following tools can be utilized:

Spare parts

In perfect world with unlimited R&M budgets for spare parts, we would stock every part locally. But every manufacturing facility has a budget, so balance needs to be found between parts availability and equipment criticality.

Machine ledger is a great tool to identify importance of equipment, which will lead to maintaining necessary stock:

Component level understanding is the key to eliminate breakdowns A machine breaks down because a component breaks down
MTTR as a part of Machine Ledger

Another way to reduce necessity of having all parts – interchangeability of existing stock. Instead of using just OEM part in description (which usually carries unique number) add manufacturers part number to CMMS, so next time, for example, you will need PLC input card for liquid filler but same part can be already in stock but assigned to case packer.

Also if you have a strong skill set, parts can be interchangeable even between different manufacturers, for example using OMRON normally-opened photoeye instead of Allen-Bradley one.

To summarize, analysis of lost time is very important but it’s crucial to follow-up on all actions related to “lack of skills or knowledge” and parts inventory management.


  1. Would there be an estimative (%) on how much MTTR would be brought down if all these procedures were followed?

    1. Thanks for your question. It all depends on your current breakdown time and number of occurrences based on formula below:
      Possibly in teen numbers.

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