TPM's Myth of Zero Unplanned Downtime
One of the goals of Total Productive Maintenance is to achieve zero unplanned downtime. While I understand the value of zero targets, in this case I think it serves to alienate some of the seasoned veterans that we desire to include in our reliability improvement efforts. Our craftsmen intuitively know that preventing all failure is not possible, this disconnect between goal and reality aids the unfortunate leap to the philosophy that their job is simply to repair the failures quickly. This problem is often compounded by rewarding reactive behaviors. For example, when I worked in the trades, I quickly learned that the best troubleshooter and fastest repairman got the most recognition, praise, and overtime.
When I was performing planned maintenance and found a problem, I felt like a doctor delivering a bad prognosis; nobody wanted to hear it, and many would prefer to ignore the problem and hope it would go away (I think they hoped I would go away as well).
What the trades understand is that there will be random and sudden failures. These failures cannot be prevented and must be managed through redundancy, spare parts, or re-engineering. What we need to help the trades see is that while some failures are random and sudden (like a flat tire from a nail) at least three other types of failures exist, and can be detected or replaced before failure. For example, age related but sudden failures can be managed through time based or fixed interval replacement. Random and gradual failures can be managed through Condition Based Maintenance and inspection.
Let's help our trades to realize that they are right that we will see some unplanned, undetectable failures, but these should only be about 5% to 10% of our work, not 50% or 60%. By recognizing that we understand there will be some unplanned failure, we can gain more buy-in from our maintenance crew and build credibility for the reliability improvement effort.