Wednesday, April 22, 2009

On improving traceability

What happens if a part somehow by-passes the machine vision system at final inspection? How do you ensure that you only ship product that has been inspected and pronounced “good”?

You could have the inspection system apply some kind of mark or label, then ask your shipping guys to verify the label is present, but is that really error-proof? When the truck is at the dock and the driver wants to leave, those are the kind of checks that get forgotten.

A better method is to set up a part traceability system where every item is given a unique number during manufacture, preferably in the form of a 2D datamatrix code. A scanner at the inspection station reads each code and writes it to a database, along with the date, time, and inspection result. That creates the inspection record.

Next, at shipping every part is scanned again as its packed or palletized. Any item lacking an inspection record is flagged, and ideally, it will not be possible to produce shipping documentation until the exception is resolved.

Yes there are probably ways in which the system can be fooled, but this kind of traceability can take you quite a way towards perfection.
So who do you go to for support in putting together a system? You could do much worse than talking to
Freedom Technologies (which is where I lifted the image above from.) Data management and traceability is what they do.

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