Mean Time Before Failure (MTBF), Mean Time To Repair(MTTR) and Reliability Calculators
Mean time between failures, mean time to repair, failure rate and reliability equations are key tools for any manufacturing engineer. it allows you to monitor the performance of components or machinery and enables you to plan production, maintain machinery and predict failures.
MTBF (Mean Time Between Failure)Mean Time Before failure is a measure of total uptime of the components(s) divided by the total number of failures. See formula:
Total Uptime is the measure of the total time a system or component is working, this is measured by taking the total time the machine should be operational, less the amount of time taken up by time to repair. Number of failures is the number of failures within this time. Careful! Make sure the number of uptime sessions matches the number of failures! Otherwise you might find your results are skewed.


Failure Rate
Failure Rate is a simple calculation derived by taking the inverse of the mean time between failures:
Failure Rate is a common tool to use when planning and designing systems, it allows you to predict a component or systems performance. Failure rate is most commonly measured in number of failures per hour.
MTTR (Mean Time To Repair)Mean Time To Repair (MTTR) is a measure of the average downtime. the formula for which is:
This takes the downtime of the system and divides it by the number of failures. again, be sure to check downtime periods match failures.

MTTR can be a useful tool for Preventative maintenance and other maintenance repair processes. It allows you to effectively plan maintenance around the time taken to repair so you can optimise time spent on maintenance to minimise downtime.
ReliabilityReliability is essentially the probability of a component or systems chance of failure and is calculated in one of two ways, if time is relatively small:
Or if the time is relatively large:
Calculating the reliability of a component allows you to design redundancy into a system. if a system exhibits a relatively high probability of failure you can place an identical compnonent in parallel to increase total system reliability:

Total System ReliabilityTotal System Reliability is a calculation which allows you to combine the reliabilities of several components to give a new value for syystem reliability. The formula for system reliability is:
