Thursday, March 3, 2011

Vision Troubleshooting #2

In "Vision Troubleshooting #1" we talked about the PoS vision system that’s been a career-killer for several engineers. (Every plant has one.) Today let’s take a different tack: we’ll call this “What do you mean, it’s not working?”

The question I want to address here is this: has it suddenly stopped functioning, or has there been a gradual deterioration? And when I say “suddenly stopped” I mean has it, for no apparent reason, decided to kick out everything? (Of course, a worse case is if it decides to pass everything. When that happens you may not even notice, but I’ll wager your customer will.)

If the change has been sudden, I suggest you look closely at the product being inspected. Is the material a different color? Has the sheen changed slightly? (Different batches of material will often look slightly different.) You might even want to ask Quality if the so-called ‘good’ item really is good. It’s not unusual to find the system is doing exactly what it is supposed to, much to annoyance of Production.

The answers to these questions may lead you into making changes to the system to cope with part-to-part variation, but that’s a different problem to troubleshooting a machine that’s just been doing a worse and worse job for months. To address that you need to read Vision Troubleshooting #3.

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