How to manage outsourcing parts for machining?

Our company is mainly engaged in the production and sales of aluminum profiles, sometimes some projects will use outsourcing parts,
Usually the number of outsourced parts is small, but there are many types, and the outsourcing manufacturers will produce more or less problems.
For example, the color of the sheet metal spray paint and powder is inconsistent, and the hole size of the steel end machining center is too large.
Every time there is a problem, the leader will "change a supplier next time",
Our company does not have colleagues who are relatively experienced and understand the peripheral processing capabilities, so I go out to the leader without arranging time.

Is there any good way to coexist peacefully with outsourcing manufacturers?

1. Choose an outsourcing manufacturer with a more complete quality system
At present, the quality management level of most mechanical processing manufacturers is still in its infancy, and there is no process and regular control. Such manufacturers will lack the complete and systematic process of analysis, sorting and solving measures when there is a problem with the outsourcing workpiece. To summarize and solve related problems, it will cause many problems to recur and affect the processing quality. Therefore, choosing an outsourcing manufacturer with a more complete quality system will avoid these problems to a certain extent.
2. The technical requirements of the processed workpiece must be accurately marked
When the workpiece is handed over to the outsourcing manufacturer for processing, it is necessary to provide the outsourcing manufacturer with clearly prepared drawings and related technical requirements documents, and inform them of the uncertain factors that may be encountered in the processing, so that the outsourcing manufacturer can learn more in detail Workpiece processing technology requirements, thereby reducing errors caused by information transmission errors, and improving the quality of the work piece.
3. Choose strong outsourcing vendors
When choosing a subcontractor, please do not choose a weakly professional subcontractor in order to reduce costs. If you choose a subcontractor only by looking at the price and not comparing the strength of the subcontractor, it is not clear whether the subcontractor is Possess relevant machining equipment and core technical personnel, which may cause the quality of outsourced processing parts to be unable to be guaranteed.
4. Establish effective information feedback
When abnormal quality is found in the machining process, if the information is not fed back in time, the abnormality is analyzed, sorted out, and related solutions are formulated, this may cause a large number of unqualified workpieces, which may lead to serious losses.