MTBF MTTR and MTTF
Mean Time Between Failure (MTBF) is a reliability metric used to quantify the expected number of failures per million hours of operation for a product. This metric is often a crucial consideration for industries and system integrators, especially in mission-critical applications. While it may not be a primary concern for typical consumers who are primarily price-driven, MTBF plays a significant role in decision-making processes for complex and reliable systems. In some cases, MTBF may be explicitly requested in a Request For Quote (RFQ), and lacking this data could disqualify a manufacturer’s equipment from consideration.
Mean Time To Repair (MTTR)
Mean Time To Repair (MTTR) represents the time required to repair or replace a failed hardware module in an operational system. When a piece of hardware fails, the repair process typically involves replacing the faulty component. Prolonged MTTR can lead to increased installation costs due to downtime while waiting for replacement parts and scheduling installation windows. To mitigate MTTR, many companies maintain spare products on hand to facilitate quick replacements. Customers often inquire about the turnaround time for repairing a product, which indirectly relates to the concept of MTTR.
Mean Time To Failure (MTTF)
Mean Time To Failure (MTTF) is a fundamental reliability measure used for non-repairable systems. It represents the expected time until the first failure of a piece of equipment. MTTF is a statistical value and is calculated as the mean over a long period and a large number of units. In technical terms, MTBF should be used exclusively for repairable items, while MTTF is more appropriate for non-repairable items. However, it is common practice to use MTBF for both repairable and non-repairable items.
The relationship between these metrics can be expressed as follows: MTBF = MTTR + MTTF
In this equation, MTBF is the sum of the Mean Time To Repair (MTTR) and the Mean Time To Failure (MTTF), illustrating the interplay between these key reliability metrics