ISO registration does not qualify the usefullness of the work done, it's only function is to monitor that you do what you write and you write what you do.
As far as the motor goes, did anyone established that it is indeed a motor issue, not a off-shore supply of 'inexpensive' brushes? The wear rate usually does not go from good to bad in a single step change, b ut comparative trending of the wear rate will be an indicator that the commutator needs to be re-cut. You would also notice the tracking changes on the surface. Was THAT part of the PM procedure?
You are very correct about ISO. IMHO, I think that unless it is followed properly and a quality system is in place, ISO is a complete joke and a waste of time and effort. By no means is it a measurement of the quality of the product. It only means that the same faulty product is made the same way each and every time. The managers and supervisors here scramble when there is an ISO audit because they want to make sure that all of the PM sheets are filled out properly and that the machine operators have filled out the daily PM sheets as it applies to their job function. There have been times in which the operators' sheets haven't been filled out for months, but when there is an audit, the supervisors tell the operators to fill the sheets out, which is falsifying information. As I said, a complete joke unless, as you said, you do what you write and you write what you do.
On our PM sheets, we do write down anything that is out of the ordinary such as whether or not there is ghosting or burning or any grooves worn into the commutator. If any of the brush holders or springs are changed, that is written down as well. Yes, we also measure the length of each brush and write it down. If there is anyting unusual about the brush condition (pitting, etc.) then it is also recorded. The individual brush locations on the commutator are also tracked.
As far as the brushes go, we only use Helwig Carbon or GE brushes. On the particular incident that I mentioned before, it was not 100% of the story. The particular motor in question had not been PM'd for 12 months (we run 24/7 and management does not want to shut the machines down for a PM, despite our pleadings. On that aspect, my hands are tied. I can't do a PM if management never wants to shut the machine down. We constantly push management to do PM's every 3 months, but if they don't want to, then we can't do it.
As I said, it had been 12 months since the last PM. Prior to that, the brushes had started to show an increasing amount of wear between PM's, but it wasn't quite at a rate yet that we would have pulled the motor and sent it out. As you have probably already guessed where this is going to lead, the brushes had gotten so short after 12 months that they started to arc on the commutator and the commutator was pitted pretty badly. One of the other shifts tried their best to try and re-surface the commutator, but it was too far gone. It ran for 3 more months and on the next PM was when we saw that the wear rate was almost 2" over a 3 month period. That was when we pulled the motor and sent it out for repair.
