The management of assets or equipment has to take into account a number of measurements and analysis. Maintenance-related metrics are an essential part of that. The three main metrics – by no means the only ones – based on their prevalence in organizations and companies are:
- MTBF (Mean Time Between Failures)
- MTTR (Mean Time To Repair)
- MTTF (Mean Time To Failure)
Briefly, to understand what each acronym covers, before looking at MTBF more in detail –
MTBF helps get a notion of how reliable your equipment is.
MTTR gives you an idea of the efficiency of your maintenance teams.
MTTF helps estimate the lifespan of non-repairable assets.
For an organization that requires physical assets to deliver, tracking equipment failure is the most optimal way to avoid disruption.
We’ll focus on MTBF, by covering the following factors:
- What it measures
- Why it is useful
- How it is calculated
- How to increase MTBF
MTBF is an important indicator of expected performance and efficiency. If the metrics reveal a high number of failures or breakdowns, manufacturers can use MTBF as a reliability metric for future design improvements on their equipment.
Introduction to failure metrics
Any and every organization needs to plan for equipment failures. But above all, you need to identify what equipment failure looks like. Failure occurs in varying degrees, from partial to total failure.
A succinct definition of failure in this context would be a system, component, or device that is no longer able to achieve the results it was designed for. An example of partial failure would be manufacturing equipment that still runs, but is producing at a lesser rate than expected. Total failure, as the name indicates, would be a complete breakdown of the piece of equipment or asset.
Reliable data is crucial to managing failure
To manage failure properly is to minimize its potential negative effects. Any proper management requires precise data. Hence, the compiling of metrics.
A close understanding and exact interpretation of metrics will help reduce guesswork at all levels. It will also give maintenance teams accurate data to make informed decisions. In order to undertake maintenance in equipment, it’s vital to collect data consistently, and for that data to be accurate.
Your maintenance history should include data and information from a number of key factors:
- Works hours spent on maintenance
- number of breakdowns and repairs
- operational time (total expected operating hours per week minus total equipment downtime)
This is where a CMMS usually comes into play, making the gathering of information and data easier on the maintenance crews. Consequently, it will reduce the risk of writing down figures inaccurately, or result in incomplete data.
Any missing data will render your failure metrics void and useless. It may lead to worse consequences, whereby you make decisions that may be ineffective or even damaging.
Streamlining maintenance operations requires identifying assets or parts with a high failure rate, firstly. Later, the cause of those failures needs to be ascertained.
When correctly used, CMMS software optimizes the gathering of information and expedites maintenance procedures.
How to calculate MTBF
MTBF calculation does not factor in assets that are undergoing preventive servicing, or parts replacement. In actuality, it sets a failure rate due to the inherent design of the asset, requiring it to be taken out of operation for repairs.
Expressed mathematically, mean time between failures can be calculated using the sum of operating time divided by the numbers of failures.
Looking at the example of a piece of machinery that runs for 12 hours, but failure occurred 3 times, lasting one hour each time.
MTBF = 12 hours / 3 hours of repairs = 4 hours
In conclusion, the asset fails every 4 hours on average.
This example shows that repair time is not counted in the calculation of MTBF.
A major factor in an asset’s failure rate is human interaction. A low MTBF may be an indication of poor handling by its operator, or even badly executed repairs, thus leading to premature failure.
To sum up, an MTBF calculation establishes not a matter of if, but when to expect a failure will occur.
How to increase your asset’s MTBF
There are incremental steps organizations can take to improve the rate of MTBF.
Increasing the amount of proactive maintenance work; making use of CMMS to establish and stick to preventive maintenance schedules should avoid critical malfunctions.
Use good quality spare parts. Fitting the equipment with compatible but cheap alternatives is never a good deal in the long run. Sooner or later, a failure will occur due to said part.
Respect the parameters set by the equipment manufacturer. Putting in elements that are over-sized or above the recommended weight will only put strain on your assets, leading to premature failure.
Clear and precise onboarding program. Irrespective of who the operator may be, equipment must be used according to the manufacturer’s manual. A clearly explained program will reduce the risk of mishandling by new operators, which would lead to shortened time between failures.
Tips on how to handle older equipment, to get the most out of their life cycle. As part of constant feedback, maintenance technicians can pass on their tips to asset operators to avoid recurring problems.
Conclusions on MTBF
The role of maintenance managers is to ensure maximum equipment availability and reduce asset downtime. The use of MTBF metrics is essential for them to uphold diligent maintenance practices and procedures. Based on the collecting of data, they can develop better asset management strategies over the long run.
Best use of failure metrics will lead to a reduction in reactive (or corrective) maintenance. Ideally, preventive maintenance should be enough to keep the organization flowing, with very little downtime. Anathema to good management is having to deal with unexpected breakdown and failure, as it pulls you into the unknown.
The best way forward is knowing how much time you’ll need for maintenance, and when it will need to be engaged. By investing in CMMS, you’re in control of the maintenance schedule, thereby keeping things churning with as little friction as possible.