What is Run to Failure (RTF)? Of course the simple answer is that you operate the equipment until it fails, a philosophy based somewhat on the age old statement, “If it ain’t broke, don’t fix it”. The main problem with this attitude is that it often ignores the consequences of the failure.
In fact, there are cases where run to failure is the best practice. However, it should be a deliberate decision and one should consider the following factors before proceeding.
1. Safety. If the machine fails is there any probability that someone might be injured? Safety should never be compromised.
2. Collateral Damage. The failure of a small horsepower motor may be of no consequence but if the failure of the motor interrupts the production process resulting in a raw material loss, then the costs go up. Also the failure of one component may cause the failure of another.
3. Cost of condition monitoring. Labor and equipment costs are in this factor. In some cases it just may not be worth it to monitor the equipment. Roof fans and such like come to mind.
4. Cost of repair. Where machines are tracked as cost centers, historical records will provide the data to again decide if it worth fixing or just let it run. Empirical data has shown that as a rule of thumb, it costs 10 times more to repair a failure vs scheduled maintenance based on monitoring.
5. Cost of replacement. Does the equipment have a spare on standby or in the warehouse? Is there a loss of production during the switch over? How long does it take to obtain a spare or repair the damaged unit and how does that effect production?
These are the major decision factors that one must evaluate before running a machine to failure although certainly not all inclusive. Others may have additional factors depending on their unique circumstances.