When you’re searching for a contract machining partner to supply the critical parts you need, how can you best determine the supplier(s) that will be able to meet your quality requirements? What questions should you be asking to separate the best from the rest?
Just like in construction, manufacturing must start with a good foundation to attain a quality product at completion. What are some of the characteristics that build a superior foundation? Machine shops that are ISO certified are a good start. ISO certification assures that the company has established procedures based on proven industry standards, and that they are consistently followed. Another key question to ask is this, does the supplier have manufacturing engineers on staff to properly review your machining needs before starting production? It’s important that a supplier fully understand your requirements, ask appropriate questions, develop a quality plan, provide input to lower costs, and develop a robust manufacturing process that builds in quality. Part of this procedure should include a process review with key personnel that will be involved in the manufacturing process for important analysis and input.
Another key question pertains to the inspection equipment that will be used to verify your part(s). First off, does the supplier have the appropriate equipment to independently and accurately confirm your part meets the required specifications? Measurements must be verified on equipment other than what was used to produce the part, or true validation has not been accomplished. Are all gages (including CMM’s) verified for accuracy that is traceable to NIST? Is there a schedule for all inspection equipment to be tested and proof that this actually is happening? Obviously, if the inspection equipment is inadequate or not being verified, the possibility of measurement errors is greatly increased.
Another key area to understand about your supplier pertains to training. Does the supplier have a formal training program for machinists that covers proper gage selection and how to use the gages correctly? Have the machinists been verified for gauging accuracy through gage R&R (repeatability and reproducibility)? A supplier can have the best equipment, but it must be used correctly and consistently, and this is only achieved through proper training.
One final area to consider for your potential supplier pertains to the technology they use. Does the supplier have the capability to utilize your solid (CAD) model for all aspects of the manufacturing process? Utilizing your solid model for fixture design, CNC program generation and part verification greatly improves data accuracy across all critical manufacturing areas. Tooling technology is another item to question. Does the supplier utilize state of the art tooling and tooling set up procedures? Variations in tooling and setup can cause major quality issues from job to job and is critical for repeatable results.
As you can see, there are many areas to consider and verify with your supplier so that you can put yourself in the best position for a quality result.
Written by Brett Baldi who has 38 years of manufacturing experience
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