One of the most difficult issues we come across in performing special processes is obtaining the proper procedural requirements and acceptance criteria.  We are certified to perform special processes for several industry primes.  Each one has requirements written to specific standards that are acceptable to the responsible engineering organization within their company.  These criteria are specified by the end user and need to be flowed down to vendors.  At times, we are working with companies that are the third or even fourth tier in the chain of suppliers.

When we ask for detailed information such as procedural or acceptance criteria, we are trying to perform an accurate inspection that will be accepted by the end user.  It is important to remember that the specification may only include the procedural criteria.  There may be a separate specification or print notes for the acceptance criteria.

For example, a customer brings in parts for magnetic particle inspection.  They tell us they just want to make sure it is “good.”  We inspect the part with a DC voltage magnetic field.  The end user reviews our certification and technique and says they require HWDC voltage magnetic field, which is specified on the print.  Our customer would be required to re-inspect parts, thus incurring additional costs.

In the above scenario the customer wants to make sure the part “is good.”  This is a very vague term.  Some acceptance criteria may allow stringers, where another specification may not allow any linear type indications.

Whenever possible please provide complete drawings from your customer to minimize uncertainties and possible rework.  Here’s a simple analogy:  if you walked into a barbershop that you’d never been to and the barber asked how you wanted your hair cut, would you say “I just want it to look good?”