MTBF
Also called: Mean Time Between Failures
MTBF is the average time a piece of equipment runs between one failure and the next. The higher it is, the more reliable the machine.
MTBF (mean time between failures) measures equipment reliability: on average, how many hours it runs before breaking down again. It shows whether maintenance is preventing failures or just chasing them.
How it works
The formula is simple: total operating time ÷ number of failures in the period. Only unplanned breakdowns count; setups and preventive maintenance stay out. Tracked per machine and per component (spindle, tool changer, hydraulics), MTBF shows where preventive work needs reinforcement and helps set part-replacement intervals.
Practical example
A press ran 420 hours in a month and broke down 6 times. MTBF = 420 ÷ 6 = 70 hours. After replacing hydraulic hoses in the preventive plan, the next month had 2 breakdowns in 430 hours: an MTBF of 215 hours.
Common mistakes
- Counting setups and preventive maintenance as failures and dragging the metric down.
- Calculating MTBF for the whole plant, which hides the problem machine.
- Looking at MTBF without MTTR: a machine that rarely fails but stays down for days is still a problem.
FAQ
What is the difference between MTBF and MTTF?
MTBF applies to repairable equipment that returns to service; MTTF (mean time to failure) is used for items that are replaced, not repaired.
Updated
Related service
CNC Pulse
Need to apply this in your company? Tell us the case and we reply with the path and the price.