Vital Questions for Finding a Great CNC Machining Partner

05 Jun.,2025

 

Vital Questions for Finding a Great CNC Machining Partner

You’re not asking for much. Reliable CNC machined parts and products that make customers happy. Simple, right?

You will get efficient and thoughtful service from kaierwo.

What’s not so simple is finding the right CNC machining partner. One that understands your needs, has the right people and capabilities, goes the extra mile, and keeps its pencils sharp so the RFQ process results in accurate quotes.

Let’s see what an ideal CNC machine manufacturer looks (and acts) like. Here are the six most important questions you should ask when evaluating a potential CNC machining partner:

  1. “What are the CNC machine shop’s capabilities and size?”
  2. “What kind of customers and industries do you serve?”
  3. “What certifications have you achieved?”
  4. “Are you able to procure castings?”
  5. “Do you have an in-house engineering department?”
  6. “What sets you apart?”

1. “What are the CNC machine shop’s capabilities and size?”

Scrutinizing capabilities is an obvious first step. Can the CNC machine company deliver what you need today and in the future? High-end machining is only possible by using best-in-class CNC machining equipment: CNC machine cutting tools, CNC lathes, milling machines, robotics, AI CNC machining, and other equipment.

Find out what casting materials can be handled by this CNC machine shop. What types of iron (gray, ductile, austempered ductile)? Aluminum? Steel and/or stainless steel? Brass? Bronze? Are there reasons why the shop doesn’t handle certain materials?

As valuable as capabilities are, size does matter. You need to be sure your CNC machining partner has the capacity to handle your needs. Obviously, a company increasing its capabilities or expanding its facilities is a sign of growth and the ability to take on large projects to meet customer demand. Be upfront about what your needs are and challenge the shop.

2. “What kind of customers and industries do you serve?”

It’s a good sign when a shop has experience in various industries; it shows flexibility and a willingness to take on unfamiliar projects. Plus, it likely means that a CNC machine shop can run complex parts with long cycle times just as easily as it can run high-volume (and less complex) parts.

Ask about specifics and listen for industries that demand high-performance parts, such as agriculture, construction, military, industrial equipment, and automotive. If professionals in those industries have experienced success working with a CNC machine manufacturer, you probably will, too.

Lastly, inquire about that shop’s Tier 1 relationships. Nothing will give you more peace of mind than knowing this shop has extensive direct OEM/Tier 1 customer interactions.

3. “What certifications have you achieved?”

Capabilities? Check. Recent growth? Check. Various industries? Check. So far so good.

Another quality check that every worthy CNC machining partner handling should pass is having an ISO -compliant quality management system (QMS).

Plus, the IATF standard — designed to be implemented as a supplement and in conjunction with ISO : — helps ensure that products consistently meet requirements and quality is routinely improved.

4. “Are you able to procure castings?”

High-end CNC machining shops value and respect the casting process. They know that, without casting, many intricate metal commercial and industrial products would be too complicated and too costly to produce.

Speaking of costly, did you know that design decisions can make up 70% of a product’s manufacturing costs? It’s vital that a part’s tooling and casting needs and costs are explored during the casting design stage. A strong partnership between the CNC machine shop, the customer, and the foundry offers cost-effective input on casting/machining designs.

A respected machining partner should help you compare both the advantages and disadvantages of different types of molding processes. Look for solid, long-term relationships with many quality foundries, meaning customers enjoy a reliable supply and the ability to hit deadlines.

Even better? Find a CNC machine manufacturer that owns the supply chain. If that shop takes responsibility for managing foundry relationships and reliably delivers completed machine parts, your life is much easier and worry-free.

5. “Do you have an in-house engineering department?”

A helpful engineering team – with numerous professionals of varied expertise – gets involved at a project’s early stages, helping develop the best possible part, efficiently and economically. The expertise these folks bring helps with design for manufacturability and creates a trusted partnership between the customer, the CNC machining contract manufacturer, and the foundry.

Quality in-house design teams provide designs/tooling quickly and cost-effectively, and can rapidly prototype a project for cast and machine tools. In addition, great in-house engineering departments have a continuous improvement team that stays on top of the latest technologies, identifying applications that could benefit customers.

The company is the world’s best cnc aluminum machining service supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

6. “What sets you apart?”

This open-ended question may seem unlikely to separate one shop from another, but the answers you get should tell you something. Here’s what you want to hear:

“Tolerances.” Different materials and processes involve different standards. Your CNC machining partner should put a premium on how its precise processes meet tight tolerances to satisfy customers’ requirements and specs.

Knowing associations’ guiding standards is critical, too. For example, a CNC machine shop that works with aluminum die casting should know and follow Aluminum Association standards and the North American Die Casting Association (NADCA).

“Quality control.” While all reputable CNC machine shops check parts, some do more by combining their workforce expertise with automated audits to ensure consistency and accuracy. Some examples: CMM inspection, Millipore testing, Custom Gaging, High Accuracy Bore Gages, Hardness Testing, Surface Finish Testing, and Roundness Testing.

The best quality control is error prevention, so ask about poka yoking, which removes mistakes from the machining process and ensures a superior part. Plus, ask about the shop’s Manufacturing KPIs (Key Performance Indicators), which evaluate performance in order to make strategic adjustments.

“Our people.” OK, this may sound cliché, but take note of exactly why people are so valuable. When you hear phrases like “better communication,” “culture fit,” “good collaboration,” “schedules and deadlines,” and “customer feedback,” it lets you know that your goals become their goals. And, because they’re a valued partner, they’re more willing to work hard for you and give you extra attention.

Aluminum cutting questions - CNC - YO! Asmbly

I am trying to cut 14mm x 14mm (.55 in x .55 in) holes in an Aluminum sheet that is 1/16" thick so that they can fit cherry mx style key switches.

I used 1/16" bits from Spetools to do test profile cuts and have broken 8 bits in the process of trying to find the right settings.

So far I have had success with rpm (bit manufacturer recommended number), 25 in/min feed rate, 15 in/min plunge rate and .15mm (. in) cut depth on each pass. Any deeper cut depth (0.20mm or 0.25mm) or faster feed rates (35 in/min) or higher rpm () breaks the bit.

However I have to eventually cut around 300 holes in a 1ft x 3ft sheet and with the current settings it would end up taking nearly 10 hrs (if the bits hold up).

I’m looking for a way to bring down the time to less than 3 hrs. I’ve these options things in mind
1. Get a better 1/16" bit from another manufacturer (Amana?) which will hopefully support higher speeds and/or deeper cuts and hold up better.
2. Get a 1/8" bit to do the profile cuts with dogholes to avoid rounded corners (Thanks Danny Miller for this suggestion) - but I’m not sure if the key switches will still fit snugly.
3. Get a 1/8" bit to do the profile cuts and do a cleanup pass with a 1/16" to get perfectly square corners

Am I missing anything else? Any suggestions on which option I should go with? Also, if you can share which bit sizes/manufacturers/settings worked for you for aluminum, that’d be welcome too - I don’t want to spend too much time/money on buying/trying/breaking bits.

Does it even make sense to try to cut a sheet this big with this many holes on a CNC or should I just find a laser cutting service? Anyone knows how much laser cutting costs?

It’s not about heat dissipation… you have to drastically low your spindle speed. Going from 1/16" to 1/4", you’re going to have 4 times the speed at the tip of the cutter. So much closer to 1/4th the spindle speed, while keeping the same feed rate. And if you lower you feed rate, you have to lower the spindle speed as well.

I frequently used 1/8" endmills to cut that exact thickness of aluminum, and I’ve bought some 1/4" endmills to try them out.

Cutting aluminum is about cutting super slowly. A high tip speed will cause galling, which will quickly kill your bits(as you found out). Watch the chips you produce, ideally they’ll almost be like a thin fingernail shaving, though I never really was able to get those. If it looks like little squares of glitter, that’s at least acceptable. Powder means you’re going way too fast. I’m sure someone will chime in with better advice, but maybe this can be a start point. Feed/speed calculators are important with metal, the “good” window for feed & speed is super narrow. Too fast, and the metal will gall because it skips over the top of the metal, rub and generate a bunch of heat, melt the metal onto the bit, and then break it. Too slow, and you’ll try to cut out too much at once, and break the bit that way. You have to be within roughly 20% of “right” to get it to cut consistently.

Drilling your entrance holes cuts down the amount of work the endmill has to do. I use the cheap 1/8" endmills from amazon, and found pre-drilling my holes so I didn’t have to plunge or ramp make it work much better, my bits lasted much longer.

I was drilling holes in solid aluminum with a friend of mine. He was fighting left and right to get them to drill, fighting and shoving super hard to get it to cut, while I was just breezing through them. I let him dull a (cheap) drill bit before showing him how to use the exact same (cheap) bit at a very slow speed… almost the slowest my cordless drill would go, and knocked them out super fast because I was cutting “right”. (I’d gone through the same thing a few weeks earlier…). The bit needs to get a proper bite on the metal, not just rub on it.

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