Posted November 11, 2019

Choosing the Right Machining Vendor

12 Questions to Ask For Your Next Project

_DSC5567-2Finding the right CNC machining vendor for your project can be a challenge, especially considering how quickly the already crowded machining market continues to evolve.

Large national shops, marketplaces, traditional machine shops, and specialty shops can each have their own unique advantages and drawbacks. Some may provide quick turnaround or low prices at the expense of quality. Others focus on quality, but at a higher price and with slower delivery.

Finding a vendor that offers the right balance between quality, speed, and price starts with understanding your unique project requirements and long-term business needs. Then, ask potential vendors the right questions to ensure that they’re a good match.

This guide will help you find a machine shop that delivers the capabilities, quality, and service needed to make your next manufacturing project a success.

PART 1: Capabilities

01. Can the machining vendor consistently deliver on time and meet your production schedule?

Speed matters. The right partner should have the manufacturing capacity to provide quick turn delivery, ensuring that you’ll have your parts when and where you need them. Look for CNC shops with an On Time Delivery (OTD) rate above 90%.

Delivery speed can depend on:

  • Vendor size—quick-turn delivery time ranges from three to five days for large national manufacturers, and up to three weeks or longer for smaller machine shops.
  • Order size—some shops are great with low-volume orders, but simply don’t have the equipment to quickly turn higher quantities.
  • Manufacturing services available, including Just In Time (JIT) manufacturing, rapid prototyping, and secondary operations.
  • Number and locations of regional production facilities within the United States.

02. Can they quickly scale up or down as needed?

Capacity may not be a major concern for low-volume prototyping, but if you anticipate requiring higher quantities in the future, you’ll need a machine shop that can scale with your needs. Tombstone fixtures and automatic pallet changers can all boost productivity and shorten manufacturing time. The number of machines matters as well. If your production quantities are in the thousands, you’ll likely need a vendor with dozens of machines.

03. Does the shop have the right equipment for your project?

L1000187Typically, there are a few different ways to machine a given part, but there’s almost always a right way to do it. Your machining vendor must have the equipment needed to produce cost-effective, quality parts that meet your project’s specific requirements.

  • What are the dimensions, minimum and maximum part sizes, and geometries that the vendor can produce?
  • What are the vendor’s tolerances and precision capabilities?
  • For CNC milling, do they support 3-axis and 5-axis-indexed machining, accommodating approach vectors for complex geometry from any angle?
  • For CNC turning, do they support turning of inside and outside features, as well as most coarse and fine metric, inch, and NPT thread sizes?
  • What is the range of finishes and secondary operations (powder coating, plating, anodizing, Alodine coating, electro polish, blasting)?

04. Does the vendor work with or supply your project’s materials?

Some materials will be a better fit for your project based on strength, durability, price, conductivity, machinability, and available finishes.

Aluminum, steel, stainless steel, copper, brass, bronze, and plastic each has its own unique advantages and drawbacks. Your vendor should work closely with you to understand your project needs and help recommend the right material for each part.

If speed is important to you, consider a machining vendor that stocks the materials you need. Ordering material can add days to your delivery time.

PART 2: Quality

05. What’s the machine shop’s quality management process?

A qualified machining vendor will demonstrate their commitment to quality by investing in:

  • A written Quality Policy to ensure that parts are consistently made to spec and delivered on deadline, including extensive documentation detailing the equipment being used, material and testing reports, and an inspection equipment testing schedule.
  • A designated quality team responsible for preventing production errors throughout every step of the manufacturing process, including First Article Inspection (FAI)—inspecting the first piece to come off the machine to ensure that it meets specifications.
  • A Quality Management System (QMS) that documents processes, procedures, and responsibilities for achieving quality policies and objectives. ISO 9001:2015 is the international QMS standard.
  • A Coordinate Measuring Machine (CMM) to ensure accuracy and confirm that each part meets your specifications.

06. Which certifications do they hold?

To help guarantee the highest possible quality, be sure your machining vendor fully understands your project requirements up front, has the proper qualifications to complete the job, and holds the relevant certifications to demonstrate that they adhere to proven industry standards and procedures.

In addition to ISO 9001, a qualified machine shop should hold specialized certifications based on your industry and objectives.

  • ISO 13485 for medical devices.
  • International Traffic in Arms Regulations (ITAR) for military and defense.
  • ISO/TS 16949 for the automotive industry.
  • AS9100 and AS9102 for the aerospace industry.

07. What training has their team completed?

A shop is only as good as their operators and engineers. Learn as much as you can about each production team member’s unique qualifications, as well as the hiring procedures and training programs in place to ensure that everyone on the team is knowledgeable and experienced.

PART 3: Service

08. Does the vendor offer design support services?

Your vendor partner should be involved early in the process, providing you with immediate design feedback and manufacturability recommendations for your project, as well as ongoing guidance to help you optimize your design.

plethora analysis exampleToday, many manufacturing vendors offer Manufacturability Analysis software custom tailored to their manufacturing solutions. These analyses are often a great, no-risk way of seeing if a vendor is able to make your part, and usually a first step toward more personal design consultations.


09. What level of communication can you expect?

Clear communication is essential to any successful project. A designated contact team should be readily available to answer your questions and implement alterations. They should be quick to respond and knowledgeable, accommodate your preferred communication method (phone, email, text), and provide you with ongoing status updates throughout the entire project.

10. What will the project cost?

Evaluating a quote requires more than simply looking at the total price. While it may be tempting to just go with the cheapest option, it can be difficult to compare the true value provided by multiple vendors based on price alone.

Before making a decision, it’s important to understand the components that make up the project’s costs, as well as the situations that could reduce or increase your expenses.

  • Does the quote offer price breaks at certain quantities?
  • How might outsourced finishing or secondary operations affect cost and turnaround time?
  • What are the fees for prototyping?
  • What are the material costs?
  • What circumstances and issues may increase the total cost?
  • What are the payment terms?

11. Can the vendor provide recent customer references?

Check online reviews and speak with previous customers to get a clearer picture of the level of service provided.

  • Did the vendor partner meet (or even exceed) their expectations?
  • Were there any defects or deadline issues? If so, how were they resolved?
  • How well did they communicate throughout the project?
  • When changes were necessary, how were modification requests handled?

12. What’s the shop’s order cancellation policy?

Your project timeline and requirements could change at any time. The right production partner should be reasonably flexible, and have a written cancellation policy with clearly-defined cutoffs and conditions.


Choosing a machining vendor doesn’t have to be complicated. By asking the right questions, you’ll get a much clearer understanding of how each one differs from the competition, why those differences matter, and which vendor will best fit your needs.

For more information about Plethora and our machining capabilities, email today.

Topics: Manufacturing, machining, sourcing