It's mandatory that all suppliers of production goods are based upon:
a: customer requirements
b: legal requirements
c: environment requirements
d: our own technical requirements as a result of many years of experience in the area of high tech components for the automotive industry.
VCST standard procedure is that the raw material needs to be secured at the suppliers (steel source, forging company and or turning company) on all kind of defects (imperfections) like cracks, seems, laps, non metallic inclusions etc...
This means that for gear manufacturing the raw material is secured by UT and EC testing before reaching VCST.
Additionally for shaft manufacturing the supplier has to demonstrate that his process prevents the presence of non-metallic inclusions and chevrons.