Two parts made to a drawing that was superseded on Tuesday

A customer issues a revision. It reaches the estimator, who files it. Whether it reaches the operator depends on someone printing it, walking it out and taking away the old one.

The old print stays

Removing the superseded copy is the step that gets missed, and it is the one that matters. Two drawings at a machine is worse than none, because the operator has no reason to doubt the one in front of them.

Revision against job

When a part is rejected, the first question is which revision it was made to. Without that recorded against the job, the shop cannot tell whether it made an error or worked correctly to superseded information — and those have completely different commercial consequences.

Repeat orders inherit the problem

A repeat order six months later is quoted against whatever drawing is found. If that is not the revision last supplied, the shop is quoting one part and making another, and discovers it at inspection.