What is MTBF & MTTR? | Formula | Example | Calculation

What is MTBF (Mean Time Between Failure)?

→ It indicates the expected time between two failures for a repairable machine or system.
→ MTBF=[(Total working time) - (Total Breakdown time)] / (No of Breakdowns)
     or        = (Total uptime) / (number of breakdowns)
→ It is very important for Total Productive Maintenance (TPM) implementation which is one of the most popular Lean Manufacturing Tool.

MTBF Calculation:

→ Three similar_machines starting to function properly at 0 hours are working until all of them fail.
→ The first machine failed at 120 hours, the second failed at 140 hours and the third failed at 150 hours.
→ The MTBF=(Total uptime) / (number of breakdowns)
                       = [(120+140+150)]/3
                       = 136.667 hours.

→ The MTBF is the average of the three failures, which is 136.667 hrs.
→ It can be calculated as the arithmetic mean between the failures of equipment.
→ In other words, It is the average duration between the failure of equipment.
→ This value of 136.667 means that a failure in the system occurs every 136.667 hours and it generates losses for the company.
→ The opportunity is to increase the duration between two breakdowns.
→ In other words, the MTBF is the timing from one failure to another for repairable equipment.

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How can I improve my MTBF?

→ We can improve it by regular maintenance of machines.
→ By implementing small Kaizen activity for the equipment.
→ Make an equipment breakdown history book and take strong preventive action on it so this breakdown will not repeat in the future.

Benefits of MTBF:

→ It is a basic indicator to predict the reliability of a machine.
→ If the_MTBF has increased after a preventive maintenance activity then this indicates a clear improvement in the quality of your processes
→ It is very useful for implementing Lean Manufacturing culture in the factory.
→ The_MTBF increase will show that your maintenance or verification methods are going good.
→ It should be used to elaborate on the company’s knowledge about processes.
→ It reduces losses in productivity and also improves the quality of the product.

What is MTTR (Mean Time To Repair)?

→ It is the average time required to analyze and solve the problem and it tells us how well an organization can respond to machine failure and repair it.
→ In other words, failed equipment returns to normal operating conditions or the mean timing duration between the equipment failure and returns to operation.
→ It is a basic technical indicator related to the maintainability of the machine and repairable parts.
→ It represents the average duration required to repair a failed component.
→ In other words, how long the machine is out of production.
→ This includes notification timing, analysis timing, fixing timing, waiting, reassembly timing, alignment timing, calibration timing, testing timing, etc.
→ The formula of MTTR=Total maintenance time/number of repairs
→ It is also called as the meantime to recovery.

MTTR Calculation:

→ A machine should operate correctly for 20 hours. During this period, 6 failures occurred. The sum of all failure duration is 90 minutes.
→ The MTTR = Total maintenance time/number of repairs
                       = 90 / 6
                       = 15 minutes

Why MTTR is important?

→ It has a remarkable effect on the organization’s profit.
→ Long_MTTR means loss of productivity and sometimes, an organization can miss an order or it can impact business relationships.
→ To reduce the impact of MTTR, organizations should have their own maintenance teams and hold critical spare parts onsite or run parallel production lines.

How can I improve my MTTR?

→ We can improve it by Team Work.
→ Implement and follow the troubleshooting manual concept or breakdown history concept
→ By providing training on quick repair and motivating people
→ Maintaining 5S
→ Follow the standardized operation procedure.
→ Keep the critical spare in stock

Benefits of MTTR:

→ It indicates the efficiency and productivity of the equipment and it has reduced after the preventative maintenance of the machine.
→ By reducing Mean Time To Repair we can improve the efficiency and productivity of the machine.
→ Lower_MTTR indicates that your company has an immediate action plan to overcome failure.
→ It should be used to elaborate on the company’s knowledge about how strong the action plan against the machine failure.
→ It reduces losses and also improves productivity and Quality of the Product.
→ It is very useful for implementing a Lean Manufacturing culture in the factory.

👉 See Also:

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➨ ISO 9001:2015 & IATF 16949:2016

➨ 7 QC Tools

➨ Quality Core Tools like MSA, FMEA, APQP, SPC

➨ Six Sigma

➨ QA & QC Topics