Ask yourself and your team what am I expecting from this subcontractor and are they able to deliver
This is the most important part of the preperation and you must be prepared very well to save you and your company embarrasment.
I focus on several aspects:
Contract and pre contract review is vital, this is a stage that has a direct impact on you. Do they really check the feasability of what they are quoting, do they really understand the demands.
Process audit, follow the process do not waste time looking for documents without signatures, some one else does this. What is important is the "spirit of the supplier" from your point of view.
Here is an example of a supplier audit plan:
8.30 - Opening meeting, presentation of Supplier and customer.
9.00-9.30 Short tour of plant.
9.30-10.00 RFQ and Contract review including treatment of orders of production approved parts.
10.00-11.00 APQP, FMEA and PPAP.
11.00-11.30 Continual Improvement, Customer satisfaction,
11.30-12.30 Purchasing, supplier evaluation and development.
13.30-15.30 Audit of process from reception of materials to shipment.
15.30-16.30 Measurement, Gauge R&R, comparison of measuring abilities.
16.30-17.00 Organisation of findings.
17.00-17.30 Closing meeting.
This enables you to cover all the aspects that are really important to you.