A special process is a production process whose result cannot be fully verified by measurement and inspection immediately after completion.
You cannot see the internal structure of a heat-treated part with the naked eye. You cannot measure the adhesion strength of a plating without damaging the part. You cannot tell the penetration of a weld seam from the surface. Verification usually requires destructive testing, which is not possible for every part.
This has a direct consequence: in special processes, quality assurance cannot rest on finished product inspection. The only way to obtain repeatable, conforming product is to keep the process itself under control.
How is it handled in automotive?
In the automotive supply chain, special processes are audited with AIAG’s CQI series assessments. Separate manuals exist for heat treatment, electroplating, painting, welding, soldering, molding, casting, rubber processing and wire harness production.
These assessments audit not the product but the system that produces the product: equipment, parameter control, calibration, personnel competence and record system. They are usually applied as an annual self-assessment, and the obligation arises through customer-specific requirements.
If you purchase the process
If you do not run the special process yourself but source it externally, the responsibility does not disappear. Since you cannot verify the product’s conformity on receipt, you need to obtain assurance from your supplier’s process control system. The responsibility for verifying the supplier’s conformity rests with the buyer.
Which CQI assessment concerns you depends on the process you run or purchase. For electroplating, for example, the CQI-11 training is suitable, and for paint and surface coating the CQI-12 training; for heat treatment, welding, casting and other processes, see the full list of our CQI training topics.