Mean time between failures definition
/What is the Mean Time Between Failures?
Mean time between failures (MTBF) measures the average time that equipment is operating between breakdowns or stoppages. It can be used to help management understand the availability of equipment, which can be a critical issue when there are process reliability issues. It can be used to plan for contingencies that require the repair of key equipment items, especially equipment associated with the bottleneck operation. In short, it is a measure of dependability.
How to Use Mean Time Between Failures
By taking steps to increase MTBF, you can increase the uptime of equipment. This is especially important for equipment that must be in continuous operation. Operations managers can use periodic maintenance checks and preventive maintenance to minimize the number of failures. This approach is especially important for bottleneck operations, where any downtime incurred will reduce the total amount of throughput generated.
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How to Calculate Mean Time Between Failures
To calculate MTBF, divide the total time a piece of equipment has been running during the measurement period by the number of breakdowns that have occurred during that period. For example, a mechanical sorter is designed to operate for 10 hours per day. The sorter breaks down after seven days of operation. The MTBF in this case is 70 hours, which is calculated as follows:
(10 hours per day × 7 days) ÷ 1 breakdown = 70 hours
The calculation is more complex when multiple breakdowns occur. For example, the same mechanical sorter breaks down twice in a 7-day period. The first breakdown occurred 20 hours from the start time, and took two hours to repair. The second breakdown occurred 40 hours from the start time and took two hours to repair before it was again operating normally. This means that the total uptime period is the sum of 20 hours of uptime, followed by 18 hours of uptime, followed by 28 hours of uptime. Given this information, the MTBF calculation is:
(20 hours + 18 hours + 28 hours) ÷ 2 breakdowns = 33 hours MTBF