Posted November 10, 2020

Assessing CNC Machining Quality Control at Your Prototype Vendor

CNC machining of a part using precision quality control methods

It’s crunch time! You’ve been working on the design for a while now, and it is time to get parts in hand to proceed with the next phase of product development. There are many machine shops that you could choose from to do this, but you need the highest quality part built as soon as possible to stay on schedule. How do you make the right choice?

While there are many factors to consider, you know already that the quality of the part is the most important. You can’t afford to rework defective parts to continue your product development, and you don’t have the time to be constantly looking over the shoulder of your prototype vendor. Here are some important questions about CNC machining quality control you should ask when considering who to use to build your next prototype project.

Key Factors of CNC Machining Quality Control in Prototype Parts

When assessing the quality of the machine shop you’re considering for your next prototype part, first explore the certifications they’ve obtained. 

To start, a machine shop should be certified and well versed in the requirements of ISO 9001. This is the standard for quality management, and they should have a well-developed documentation process in place for their quality systems.

In addition, different certifications may apply depending on your industry:

  • ISO 13485: Certification to this quality management system standard demonstrates the shop’s compliance with the rigid requirements of the medical industry.
  • ITAR: International Traffic in Arms Regulations certification is required for any manufacturer building parts used by the Department of Defense.
  • ISO/TS 16949: Certification to this global technical specification and quality management standard is required for builders of automotive parts.
  • AS9100 & AS9102: These standards outline the quality management system and first article inspection requirements for the aviation, space, and defense industry. Though not legally required, aerospace parts manufacturers that carry these certifications can most effectively partner with organizations in these industries.

Once you determine a vendor’s certifications meet your requirements, you then must understand the shop’s processes for monitoring and controlling for quality. To do this, review:

  • Inspection procedures: Does the shop inspect each part for accuracy? Do they offer first article inspections? 
  • Accuracy of equipment: Does the shop leverage advanced technology or software to ensure precise machining to your exact requirements?
  • Training: How are staff kept up to date on quality processes?
  • Quality team: Are there designated, in-house quality team members? How do they interact with machinists on the floor?
These initial factors give you a solid idea of a shop’s quality processes. As with anything, of course, there’s more to consider.

Additional Capabilities to Consider During Your Assessment

When assessing the CNC machining quality control of a prototype part vendor, ask these additional questions to get a better picture of their commitment to quality.

Can the shop handle your prototype order without delays? 

Not receiving your prototype when you expect it costs you time and money. Ask about the shop’s on-time delivery rate—it should be 90% or above. Also consider factors that can affect turnaround time, such as: 

  • Size: Larger manufacturers can often turn a prototype within five days, while smaller shops may take up to three weeks.
  • Service: Vendors that provide manufacturing as a service ultimately help to bring products to market more quickly due to their ability to rapidly prototype on demand and provide just-in-time manufacturing.
  • Location: A shop with locations in the United States and near you will be able to deliver your part in a more timely manner.

Can the shop scale your project from prototyping to production?

To start, you may only be interested in low-volume quantities to assess the form and function of your prototype. However, working with a shop that’s prepared to produce higher volumes allows you to scale whenever you’re readywithout having to find a new vendor. Ask about the automation available at the facility, which can help speed up production, as well as the number of machines, to ensure the shop can meet your short term and long-term needs.

Will the vendor’s facilities and equipment be able to handle your project?

This is where it’s critical to dive deeper into the shop’s machining capabilities so you get a quality part from the outset. For CNC milling, consider if the shop’s equipment supports three and five-axis indexed machining. Can they accommodate complex geometries? 

For CNC turning, can the shop support turning of inside and outside features? Ask about hole size limitations, as well as grooves and thread size. Also find out how much live tooling equipment the shop has so you can plan your design to leverage those capabilities and reduce your production costs. For all processes offered, also ensure you understand the shop’s part size limitations and tolerances for different materials.

And, while you may not invest in finishes on your prototype, if you anticipate scaling to production, consider if the shop offers secondary operations, such as anodizing, powder coating, or plating.

Are the materials you need for your project stocked? 

The procurement of materials can add significant delays to your prototype project. Most quality shops will maintain an inventory of the materials you’ll need, such as aluminum, steel, plastics, brass, copper, and bronze. They’ll also have suppliers on standby for special orders if a unique material is needed.

Will the shop evaluate and optimize the manufacturability of your design?

How a shop’s engineering team engages with you to evaluate your design is often a leading indicator of the vendor’s commitment to quality. The ability to apply the vendor’s engineering input on manufacturability enhancements and optimizations ultimately leads to a high-quality prototype and final product.

For example, our evaluation process at Plethora includes a manual review of your design data instead of merely building off the CAD input. This gives us the ability to understand beforehand what type of tolerances your design needs, and how we can better respond to those requirements.

Commitment to Quality Is Essential in Prototype Part Production

Prototype parts that don’t measure up cost you in alterations and product development delays. Working with a vendor that’s committed to providing the highest level of qualityfrom initial prototypes to regular production runsis essential to the ultimate success of your project.

At Plethora, one step we’ve taken to fulfill this commitment is to designate quality control team members to work alongside our machinists on each shift. This allows us to infuse a higher level of quality control throughout our entire production process in addition to our regular manufacturing inspections.

To find out more about the quality control methods employed at Plethora, as well as the industries we serve, take a look at our quality policy. We are an ISO 9001-certified and ITAR-compliant CNC machine shop. To get started on a new part evaluation, please upload your files to Quote My Part or give us a call at 415-726-2256.

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The Plethora Team

The Plethora team is your go-to CNC manufacturer for hardware done right the first time. We have the tools and experience needed to create high quality custom parts quickly and with precision, whether you need a prototype or production run.

Topics: CNC machining, Quality