Does Precision Have to Be Painful?

The more effective and efficient processes result from accuracy being easy.


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When I write an article, I generally show my sources an advance copy. When Aerodine Composites reviewed an early version of this article, I got a question back that I didn’t expect. One of the readers at this company wondered whether the application described came off sounding overly casual, and therefore imprecise.

The article is about the use of on-machine probing to simplify setup by orienting a machining program’s XYZ coordinate system to match the actual orientation of that part on the table. This method of setup is certainly not unprecedented, but it is uncommon—which is what makes the story interesting. If there is any implication that the resulting process is uncontrolled or imprecise (and I’ve since reworked the story a bit to avoid that implication), then let me end that misperception here. Aerodine gives care to programming each part’s probing routine, and it is that very care that makes the resulting process seem casual, perhaps, because that care makes it possible for the machine’s operator to be relatively unconcerned about the exact position of each piece from one setup to the next. To me, that lack of concern is the whole point.

We tend to expect that precision ought to be difficult, even personally costly. That expectation comes from our heritage. In manual machining, the tightest tolerances are met by those who have spent years developing skill, and who painstakingly consider each manual step with an eye to holding the required precision.

But efficiency is about avoiding pain, and CNC expands the options for doing this. Here, I use “pain” in the broad sense (the same sense as “painstaking”). All of those steps in the process in which extra diligence or exertion are needed are pain points where the process will slow down or break when that diligence or exertion is not there. The simple and easy processes are therefore the most naturally efficient ones, and it is worth a combination of both technology and front-end engineering to achieve a process that will benefit from this simplicity going forward.

Aerodine achieved this. The company found a way to realize consistent, day-by-day precision in the drilling, milling and trimming of its curvy, short-run composite workpieces. The technique of probing for program alignment is not a universal solution to setup challenges, but I have a feeling this technique might be the answer for more facilities than are currently employing it.

To the question in the title above, there is no obvious response. Does precision have to be painful? One answer is yes. Manufacturers that succeed at holding fine tolerances do so by taking steps that not every shop can perform. But if the question is understood to ask whether precision has to be painful every day, then the most capable processes are likely to arise from the answer, “Maybe not.” The shop best able to achieve precision consistently is the one that has taken care to achieve it naturally and gracefully.