Mean Time Between Failure & Mean Time Between Repair

1. MTBF & MTTR
- Example
- Equation
- Definition

2. (rata – rata repair time)
(rata – rata kehandalan equipment time interval)
Equation on Examples

3. Definition
• "Mean Time" means, statistically, the average time.
• MTBF: "Mean Time Between Failures" is literally the average time elapsed from one failure to the next. Usually people think of it
as the average time that something works until it fails and needs to be repaired (again). As reliable production processes are
crucial in a Lean Manufacturing environment, MTBF is vital for all lean initiatives
• MTTR: "Mean Time To Repair" is the average time that it takes to repair something after a failure.
• MTTF: For something that cannot be repaired, the correct term is "Mean Time To Failure" (MTTF). Some would define MTBF – for
repair-able devices – as the sum of MTTF plus MTTR. .In other words, the mean time between failures is the time from one failure
to another. This distinction is important if the repair time is a significant fraction of MTTF.
• Example:
• A light bulb in a chandelier is not repairable, so MTTF is most appropriate. (The light bulb will be replaced). The MTTF might be 10,000 hours.
• On the other hand, without oil changes, an automobile's engine may fail after 150 hours of highway driving – that is the MTTF. Assuming 6
hours to remove and replace the engine (MTTR), Mean Time Between Failures is 150 hours.
• Like automobiles, most manufacturing equipment will be repaired, rather than replaced after a failure, so Mean Time Between
Failures is the more appropriate measurement.