CNC machining is a highly accurate and precise manufacturing process that is commonly utilized in projects that require one-offs to hundreds of pieces. Machining is used to produce parts out of metal, plastic, composites, and natural materials. It is commonly used across low and high volume requirements, and as a bridge technology between low and high volume.
Given all of the capability of CNC machining, you may be interested in buying a CNC machine. But what if you’re less interested in capital investments and more interested in identifying a great CNC Machining service to do manufacture your designs for you? To identify the best CNC machine shop for your business needs, there are a number of key characteristics you should consider.
Can the machine shop meet your tolerance requirements? .005″ tolerances are standard for most CNC machinists, but certain manufacturers are capable of hitting tolerances well below .001″. Present a drawing and make sure the supplier can meet all of your tolerance requirements. The right CNC machine shop for your business should be able to commit to hitting the tolerance requirements you need either straight off their machine, or provide a clear post-processing plan if the primary machining step won’t do. Remember too that if your tolerances aren’t very tight, working with a precision machinist that provides parts well beyond what your application needs may be overkill and can create unnecessary costs.
Can the machine shop cut the specific material you are looking for? While it is not uncommon for shops to cut a wide variety of alloys, they also generally specialize in a few. For example, a CNC machine shop might be experts in cutting stainless steel and aluminum, but have less experience with harder metals like tantalum, vanadium, titanium, or inconel. It’s generally best to engage suppliers who already run your material rather than convince a supplier to run a new material. There is typically a learning curve for shops running a new material in the way of procuring appropriate cutting tools, defining material feed rates, and optimizing cutting speeds. A great CNC machining partner won’t make you suffer through that learning curve with them or they will be up front in telling you about the learning curve ahead and how they plan to make coming up that curve painless for you.
Is the machine shop in the right geography for your needs? The supplier’s geographical location can have a number of key impacts. For one, international suppliers may be subject to import/export impacts that can impact both your project pricing (tariffs) and delivery (customs) timeline. For two, even when weighing two domestic CNC machine shops, manufacturers in your state may be subject to different tax requirements than suppliers shipping from out-of-state. For three, certain contract manufacturers will have various locations around the globe to dynamically leverage what’s best for you. Quite simply, there is no cut and dry requirement for a CNC shop’s geographical position. The right CNC machine shop partner for your business may come from anywhere in the world, so long as it is a fit for your requirements. Know what those requirements are up front to save yourself and prospective partners that aren’t a fit some time.
Does the machine shop have machines big enough to meet the needs of your project? Certain parts simply don’t fit into the work envelope of every CNC machine. On the flip side of the coin, bigger machines represent bigger capital investments – and with that higher hourly machine rates. Particularly with small volumes, a good rule of thumb is that you’re doing things most economically when the machine fits the build envelope comfortably. As you scale to larger production volumes, the capabilities of bigger or newer CNCs running small parts can sometimes offset the higher machine rate in savings of time or post-processing. But for smaller volumes, they can come with higher setup costs that kill a per piece price. A great CNC machining partner should be able to handle what you intend to throw at them – or present a clear plan to address any shortcomings of their machine shop.
Does the machine shop carry the certifications – commonly referred to as “certs” – to support you from prototype to production? While anyone with a few bucks can buy a CNC machine, it takes more money – and perhaps more importantly, time – to get industry-recognized certifications. Common certifications are ISO9001 (general), AS9100 (aerospace), ISO13485 (medical), and TS16949 (automotive). FDA-certification and ITAR compliance are also commonly requested certifications that a facility may or may not have. And there are a host of others. To the extent your production work will require a certification, it’s good to sort through that up front. That isn’t to say that great (and sometimes more affordable) work can’t be delivered by shops without certs – or without the most current certs. But it’s generally helpful to know that in advance. A great CNC machining partner will be up front with what certifications they carry and how they ensure quality.
Does the machine shop have the ability to scale with you? Some shops have dozens or hundreds of machines. Others may just have one or two workhorse machines. Knowing the capacity of your manufacturing partner in advance is helpful in a few ways. For one, if you anticipate providing a variety of designs and materials, a CNC machine shop’s access to a range of technologies such as mills, lathes, sheet metal forming, and laser or water jet cutting technologies will let you know if they can handle everything you’ll throw at them. Moreover, taking stock of their capabilities gives you a degree of transparency into when certain production volumes might stretch the capacities of your partner to the limit. A great CNC machining partner doesn’t necessarily need to be able to scale from prototype to production with you – such partners sometimes carry extra overhead. But many great CNC machine shops do have that ability, and those that don’t should be up front about their limitations and willingness to share information so that you can scale production elsewhere if necessary.
Finishing / Post-Production / Inspection
Does the CNC machine shop you are considering have the post-process technologies to meet your needs? For some parts, all that you need of a machine shop is a functioning machine – no critical tolerances or requirements for surface roughness or finish. But for other parts, post-processing is everything. Need a multipoint CMM or optical inspection? Need anodization or heat treatment? Need a grit blast or shot peen? Need assembly and packaging? Not every shop carries these capabilities in-house, and going externally can add weeks or months to a project timeline. A great CNC machine shop will be able to meet your typical requirements – and often times not much more than that! Don’t necessarily assume a shop having everything under the sun is the right one for you. To the extent many of those technologies are overkill for your needs, they might represent unnecessary overhead that gets baked into the prices you pay.
Does the CNC machine shop provide you with the right tools to keep in touch with them and track work through to completion? Many CNC machine shops will provide online tools for uploading RFQs, delivering you quotes, tracking projects, logging past jobs. Some will go a step further and provide things like online parts inventories and visual access to your programs via videoconferencing. A great CNC machine shop will provide you with enough tools to stay on top of progress without having to pay them a visit in person, especially in light of the global pandemic.
Finding a great CNC machine shop that you can truly partner with can be a real challenge. And as often as not, finding just one partner isn’t enough. Most companies find that they need multiple manufacturers to meet the variety of requirements they expect to encounter – from material selection to scaling to certification and beyond. This also serves to hedge them against risk should their primary partner ever be backlogged. The most important thing is clear and transparent communication with a prospective partner around the questions we have outlined above, so that you understand up front what their capabilities and limitations are. Armed with that knowledge, you can build sourcing plans and supply chain resiliency accordingly.
You may note that somewhat conspicuously we didn’t call out delivery or price as key questions to ask. This isn’t an omission, even though these are two critical components to any good manufacturing partner. The main thing to understand is that depending on your requirements, delivery and price expectations will vary wildly. Understanding a supplier’s answers on the above dimensions will go a long way in helping you understand price and delivery variance – and in helping you understand when a given partner is the right one. Circle around to discussions of price and delivery once you have a tangible project in hand to quote.
Does this sound like a lot of work, or you aren’t quite sure where to identify machine shops to ask these questions of? Conveniently, 3Diligent ProdEX offers you multiple ways to identify the right CNC machining solution for your needs. With ProdEX Connect, you can be introduced directly to machine shops that meet your project requirements, and you can both use our embedded tools to manage your projects. With ProdEX PM, you can outsource supplier management to the ProdEX team, so that we can dynamically utilize the best suited manufacturers from our network of hundreds worldwide. You can sign up for a free ProdEX account here and get matched to qualified suppliers in minutes!