Mean Time To Repair (MTTR) & Mean Time Between Failure (MTBF)

Mean Time To Repair (MTTR) & Mean Time Between Failure (MTBF)

What is Mean Time To Repair (MTTR)?

 - Mean time to repair (MTTR) is a maintenance metric that measures the average time required to fix and repair failed equipment.
 - It shows how quickly an organization can respond to unplanned breakdowns and repair them.
 - MTTR calculates the period between the start of the incident and the time when system returns to production. This takes into account the time to: 
 1. Notify Technicians.
 2. Diagnose the issue.
 3. Fix the issue.
 4. Allow to cool down the equipment.
 5. Reassemble, align and calibrate the assets.
 6. Set up, Test and start up the asset for production.

Why MTTR is Important?

 - A lower MTTR indicates that your company has quick answers to problems in their processes, which demonstrates a high degree of efficiency.
 - To reduce MTTR, organization should have their own manitenance teams with extra critical spare parts or run parallel production line to avoid line stoppage.
 - It allows you to effectively plan maintenance around the time taken to repair so you can optimise time spent on maintenance to minimise downtime.
 - It reduces losses and improves productivity and quality.
 -Low MTTR means your company has an immediate action plan to overcome failures.

How to reduce MTTR

 - Maintain 5S.
 - Follow the standard operating procedures.
 - Keep the critical spare parts in stock to avoid stoppage.
 - Follow the breakdown history concept and troubleshooting concept.
 - By providing training on quick repair.

Example 

 - A machine should operate correctly for 80 hrs. during this period, 40 min, 30 min and 35 min failures occured.
MTTR = Total maintenance time/No. of repairs
            = (40+30+35)/3
            = 35 Mins.

Mean Time Between Failure (MTBF)

 - Mean time between failures (MTBF) is the average time between all breakdowns.
 - The higher the time between failure, the more reliable the production system.
 - MTBF comes to us from the aviation industry, where system failures mean particularly major consequences not only in terms of cost, but human life as well.

Why MTBF is Important?

 - MTBF analysis helps your maintenance team reduce downtime while saving money and working faster.
 - It reduces losses in productivity and improves the quality of product.
 - The increase in MTBF will show that your maintenance or verification methods are being well run.

How to increase MTBF

 - Proper Preventive manitenance schedule
 - Checking maintenance check like proper lubrication, aligning calibration system, oil level, cleaning etc.
 - Maintain 5S.
 - Follow the standard operating procedures.

Example

 - A machine runs 400 hrs in one month. in this peroid asset broke down 4 times, then
MTBF = Total Uptime/No. of Breakdowns
            = 400/4
            = 100 Hrs.

Mean Time To Repair (MTTR) & Mean Time Between Failure (MTBF)

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