Test and Inspection Assembly

Hoffmann on Testing: Software for Everything...Really?

If the assumptions are wrong, the conclusions are not likely to be very good.

February 14, 2012
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A wise engineer once remarked that, “If the assumptions are wrong, the conclusions are not likely to be very good.” We engineers buy into that, right?

After all, we are logic-driven, faithfully following good mechanical and algorithmic processes to an appropriate solution. In this case, designing a leak test or solving a test problem on a high-speed production line. Then someone brings a software guy in the room...

Unfortunately, some technical types start out with the wrong assumption: That software can fix problems often caused by product dynamics or defects in tooling. When the root problem is mechanical in nature, you have to get to the underlying issues.

Still, they persist in seeking an easy way out—like using software to compensate for mechanical factors they probably don’t understand. This assumption is likely to introduce further errors into the process.

This will surely be the case anytime a fixed off-set is used to compensate for a variable effect, such as seal creep in a leak test fixture or fluctuating signals from a damaged torque sensor.

When an arbitrary function is used to compensate for a variable effect of indeterminate function, such as temperature compensation using an average of readings, well, those assumptions are probably not going to be fruitful, either.

As engineers we should prefer conclusions based on solid analysis of the actual situation. That’s why upfront consideration of real-world test requirements, which may include detailed feasibility and correlation studies, will always yield a best-practice approach.

The beauty of such analysis is that it lowers production line inefficiencies, while being more cost-effective. It’s also a process and benefit that software can’t provide. One of the more straightforward ways to optimize production uptime is by adding electronically self-calibrating leak testers that automatically validate entire test systems while they are in operation.

These are the kind of things you can’t do with off the shelf software. Really.


Jacques Hoffmann is president of InterTech Development Co., which designs and builds equipment for leak testing, functional testing and test-centric assembly. He can be reached at 847-679-3377.

 

Editor’s note: “Hoffmann on Testing” is part of a series of guest spots by industry experts that will appear regularly on ASSEMBLY’s blog page. Check back frequently to read more commentaries from Jacques, as well as contributions on automated assembly systems, machine vision, robotics and ergonomics.

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Cody Steele
February 15, 2012
I agree. It sounds a lot like Deming's funnel experiment. Fixing something that's not the real problem inevitably makes things worse. http://tinyurl.com/837xu2a —Cody Steele, Statistical Communications Specialist, Minitab, State College, PA

Debi Anderson
February 15, 2012
Yes. Analysis is only as good as the data that is input. If you don't understand or look at the mechanics of the process the data is flawed. —Debi Anderson, engineer, Aero Brake & Spares Inc., Austin, TX

Ron Scicluna
February 23, 2012
I think the goal of test and assembly software is to “look for” failures identified through an FMEA. This analysis is the design and production engineer’s best guess as to what unacceptable results might look like and what material or process discrepancy is the likely culprit. If designed right, the software should be able to identify a performance trend and, based on the FMEA breakdown, point out the most likely cause. Apart from that there is no substitute for honest to goodness root-cause analysis. The results can be used to improve materials and assembly processes. Of course, the software can’t be any smarter about potential failures than the FMEA (and the programmer) tells it to be. —Ron Scicluna, PPI Consulting Group, Chicago

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