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Grinding Slow, Grinding Fine
June 27, 2022
Another benefit of walking the shop floor regularly is an early warning of problems that will require your attention. Most of my work has been with low-volume or “one-off” gearboxes where every component is “handcrafted,” so perhaps I am overly sensitive to the need for constant vigilance on part quality. Perhaps — but it never hurts to be careful with prototype or pre-production runs on mass-production parts, either.
Too many engineers refuse to get involved with the resolution of non-conforming parts. This attitude of “Make it like the damn drawing” infuriates the shop and encourages them to delight in humiliating that same engineer when a drawing mistake slips through. Management naturally tends to side with the shop and your life will be further complicated if you dig your heels in on re-designs and rework.
So, unless you are absolutely certain you will never, ever make a mistake, it is necessary to involve yourself in the fate of less-than-perfect parts. I was a terrible machine operator as an apprentice and know first hand how the slightest mistake can turn “jewelry” into scrap. Schedules and bottom lines suffer damage if your answer is always “Throw it out and start over.”
I am not saying you should look the other way on defects, but rather that you use each case as an educational opportunity. Ask the right questions in a respectful way, because doing so gets truthful responses and finds the root cause. Sometimes that “root cause” will turn out to be you having unrealistic expectations on process capability. Other times it will be honest mistakes by people trying to get things done.
Occasionally, the debate over the rework procedure will reveal some highly amusing (provided you are not personally involved) circumstances. Like that time our multi-national team argued back and forth over whether to plate certain bearing journal diameter. The “It will be OK after polishing” side prevailed, only to have the damn part fall off the truck on its way to assembly and need that plating after all.
To quote a famous philosopher, “Things are right or wrong depending upon their circumstances.” Sometimes they really do need to throw it out and start over. Other times, a careful rework or repair will produce a part that performs every bit as well as a “perfect” one. We’ll need a few blogs to cover this topic.
