MTTR | Mean Time To Repair | MTBF | Mean Time Between Failure | MTTF | Mean Time To Failure

MTTR | Mean Time To Repair | MTBF | Mean Time Between Failure | MTTF  | Mean Time To Failure 

What is MTTR, MTTF & MTBF?

👉 With the help of MTTR, MTTF and MTBF we know about Availability of machine or System.

👉 (MTBF) Mean Time Between Failure and (MTTR) Mean Time To Repair are two important KPI's in Plant maintenance mangement and lean manufacturing.

MTTF:

“Mean time to failure” is the average time that a machine will function before it fails. It is the mean lifetime of the machine.

MTBF:

“Mean time between failure” is a metric that concerns the average time elapsed between one failure to next failure. 

It’s calculated by a formula;

MTBF = (Total available time - Total breakdown time) / Number of breakdown

              or 

MTBF = MTTF + MTTR

How to improve MTBF:
👉 Through regular maintenance of machine.
👉 By implementing small Kaizen activity for the machine.
👉 Make a machine failure history book and take a strong preventive action on its so this failure will not repeat in future.

Benefits of MTBF:

👉 It is the basic indicator to predict the reliability of a machine.

👉 The MTBF increase will show that your maintenance methods are going good.

Example of MTBF:

This table is taken for an example, its data is taken on a random base to understand you.

MTBF = (Total available time - Total breakdown time) / Number of breakdown

MTBF = (92.5 - 3.5) / 5

MTBF = 17.8 Hours

Note:

⇒ It's value should be maximum always.

⇒ This index reveals that a failure in a machine occurs every 17.8 Hours.

MTTR:

"Mean Time To Repair" is the average time that it takes to repair something after a failure. This includes notification time, analysis time, waiting time, reassembly time and testing time etc.

It’s calculated by a formula;

MTTR = Total breakdown time / Number of breakdown

Why MTTR is important:

👉 Long MTTR means loss of productivity and loss of organization's profit.

👉 Due to long MTTR sometimes,  a company can miss orders or it can impact on 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 to improve MTTR:

👉 We can improve MTTR by team work.

👉 Implement and follow the breakdown history concept.

👉 By providing training on quick repair and motivate people.

👉 maintaining 5S at our workplace.

👉 Keep critical spare parts in stock.

👉 Follow the SOP's (standardize operation procedure).

Benefits of MTTR:

👉 It indicates the efficiency and productivity of a machine.

👉 it reduces losses in profit.

👉 It improves productivity and quality of the product.

👉 By reducing MTTR we can improve the efficiency and productivity of a machine.

Example of MTTR:

MTTR = Total breakdown time / Number of breakdown

MTTR = 3.5 / 5

MTTR = 0.7 Hours (42 minutes)

Note:

⇒ It's value should be near to Zero always.

⇒ The Company  knows that every 17.8 Hours (MTBF), the machine will be unavailable for 42 minutes (MTTR) 

Availability: 

👉 It is the ratio of the time a machine is functional to total time required.

👉 Higher the availability, Higher the operational time and Higher the accessibility.

Formula:

Availability = MTBF / (MTBF + MTTR) X 100

Availability = 17.8 / (17.8 + 0.7) X 100

Availability = 96.21%

Note:

⇒ It's value should be maximum always.

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