Most companies use traditional maintenance Key Performance Indicators (KPIs) to track management and machine operation. Two of the most common ones are MTBF and MTTR, or Mean Time Between Failures and Mean Time to Repair.
Industries operate at a constant rhythm, especially in today’s fast-paced manufacturing environment – that is why avoiding equipment failures and unplanned downtime has become more crucial than ever, and that is where KPIs come into play.
A single hour of downtime in production lines can have serious consequences, such as delays in delivery schedules and significant financial losses for companies.
Conducting detailed inspections on machine performance, availability, and reliability is crucial. This is what allows factories to operate at peak performance and implement successful predictive maintenance strategies.
Equipment Failure Prevention: A Guide for Maintenance Managers
KPIs are established to assist maintenance teams, indicating how frequently machine failures occur and how quickly technicians can repair them. Below, we’ll further explain these metrics and explore how to calculate MTBF and MTTR with examples.
What Is MTBF?
MTBF stands for Mean Time Between Failures, which refers to the average operating time of a piece of equipment before failure. If a machine remains operational for an extended period of time without any interruptions, MTBF stays high – so the higher the MTBF, the better.
MTBF is a KPI used for repairable systems where interventions are needed to replace components, such as changing a shaft’s bearings in a centrifugal pump.
Engineers and technicians responsible for inspections use MTBF to track and detect potential defects in the maintenance activities previously performed on that same equipment. This consequently leads to a more in-depth investigation into the root cause of a failure, and from there, it is possible to determine the best way to rectify it.
How to Calculate MTBF
MTBF is calculated using an arithmetic average. Essentially, this means taking the data for the desired period (it could be six months, a year, etc) and dividing the total operating time by the number of failures during that same period.
The formula to calculate MTBF would be:
Total available time – Lost time / Total number of stops or Machine operating time / Total number of failures
Since this KPI is also used to calculate reliability, MTBF does not take into account planned downtime during scheduled preventive maintenance. Instead, it focuses on unexpected interruptions in production and failures.
Let’s use one of TRACTIAN’s clients as an example: a hydraulic pump in a CNC machining center.
The CNC machine has an operating window of 21 hours per day from Monday to Friday, which totals 105 hours per week. Over the course of one week, the hydraulic pump stopped the cutting tool lubrication system on 3 occasions, resulting in a total of 11 hours of downtime during that week.
This is how to calculate Mean Time Between Failures, or MTBF:
When KPIs are well implemented and managed, they become one of the greatest allies for maintenance teams. Want to reach maximum asset availability in your company? Click here to learn more.
