What does “mean time between failures” (MTBF) measure?

Mean Time Between Failures (MTBF) is a critical metric used in maintenance and reliability engineering to assess the reliability of a system or component. Specifically, it measures the average time that elapses between one failure and the next during operation. This means that if a system experiences multiple failures over a defined period, MTBF helps to calculate the average duration of time that the system operates without experiencing a failure.

This metric is essential in various industries because it provides insights into how long a piece of equipment can be expected to function correctly before a failure occurs, thereby assisting in planning maintenance, reducing downtime, and improving operational efficiency.

In contrast, the other choices focus on different aspects of maintenance or performance. For instance, total downtime addresses the period when equipment is not operational due to failures or repairs, which is a different concept. The duration of each maintenance session refers to how long maintenance tasks take, thus not providing information about system reliability. Lastly, the frequency of repairs addresses how often maintenance work is needed rather than how reliably the equipment performs over time. Understanding MTBF allows organizations to enhance their maintenance strategies and optimize equipment usage effectively.