Tuesday, March 1, 2011

Vision Troubleshooting #1 – has it ever worked?

Have you noticed how the newly-hired manufacturing engineer often finds “fix vision system” on his to-do list? In my experience there’s usually at least one vision system that gives manufacturing a constant headache but no one has ever had the time to sort it out. So let’s take this as our troubleshooting start point. What do you do?

The first question to ask is, has it ever worked?

That’s not as dumb a question as it might seem. It’s not uncommon for engineering to give up trying to fine tune a new system and just accept it the way it is, flaws and all. Everyone knows it doesn’t do quite what it was supposed to, but there’s an implicit understanding that they’ll all live with it for now.

That’s OK until someone new arrives and feels the need to question why it can’t be made to work properly

So as you stand clueless, watching the system kick out good product, here’s your start point: find out how it performed when new. Dig out the acceptance records, the run-off records, whatever you call them in your company, and see how it ran back then.

Now, compare the historical data with the way it’s running now. Is it running the same, worse, or don’t you know? (If you can’t find any historical data you’ll be in the ‘don’t know’ category.)

If it’s running just the same as when new, then you have a design problem, not a maintenance problem.

If you don’t know, then you’ve just learnt the importance of keeping baseline data. Your next system will have a baseline, won’t it? So, in the absence of formal data on the when-new performance, ask around, find out what people remember, and try digging out quality data. Have reject rates gone up since installation? Down?

Now if you’re in the fortunate position of being able to say ‘yes, it’s running worse,’ then you start on the problem solving. We’ll start on that in Vision Troubleshooting #2.

No comments: