I will try to explain it in a way that is as simple as possible since it is a boring reading. The operation and management process involve:
1) Select qualified suppliers
a) Inspect the background of the suppliers including its factories, sources of materials, labours (some companies forbidden their suppliers hiring child labour), etc.
b) Supply selection requirements to potential suppliers
c) Potential suppliers need to prove they can meet the requirements and certified examination reports of their products often are mandatory
2) On going inspection of products and suppliers
a) Suppliers need to provide 化驗報告 for the products they supply. The frequencies and the type of化驗報告 required will depend on the products and company policies.
b) QC (quality control) team will inspect the received products on receiving (include 化驗) according to the company standard. If the shipment is for sourcing procurement to be exported. The QC team always inspects every shipment.
3) Rate and review suppliers
a) Rate suppliers based on criteria and quality is certainly one of the most important aspect
b) Eliminate unqualified products and suppliers
P.S. this is not something I made up myself and I was involved in a project relating to one of the companies I mentioned.