How a Finite CNC Machining Toolset Boosts Cycle Time

Posted On February 6, 2018 By Matt Ahart

Similar to our injection molding service, CNC machining at Protolabs is a bit unconventional. In order to machine parts as fast as possible, we’ve developed automated processes to quote parts, analyze design manufacturability, and generate toolpaths. Additionally, our standardized toolsets help us streamline our machining center operations and boost cycle time.

Why a Finite Toolset?

Whereas a small machine shop will find the exact tool to machine a part geometry—or in some cases make it themselves—we use a finite, standardized toolset across our machining process.

Why do we do this? In one word—speed. We group materials into similar categories and have standard toolsets consisting of various end mills and drills for each. This means we can machine parts faster and save you weeks of development time and reduce manufacturing costs.  This combination of carefully selected tools is aimed at accommodating the most amount of part geometries while maintaining the quick turnaround times often required by product developers.

haas cnc machine toolset
Our machining toolset includes a combination ball and flat end mills. For metals like titanium and steel, we also use bull nose end mills.
Milling Holes, Threads, and Off-Axis Features

Our finite toolset does, at times, require us to take a creative approach to milling features like holes, for example. In most shops, holes are drilled using a drill bit—not that surprising. But we typically rely on our end mills to create holes. Drilling holes with end mills enables us to machine a variety of hole diameters, slots, and other features all with a single tool. This cuts down on cycle time (and subsequently cost) and has the added benefit of improved surface finishes within holes.

Next let’s talk about threading. A traditional machine shop will typically use a tap or die to cut threads into a part. This is a manual process that requires the technician to remove the part from the machine and then tap the holes by hand or with a machine such as a drill press. Whenever manual labor comes into the equation you can expect significantly longer manufacturing time.

To reduce the amount of time it takes to cut threads, we take a more automated approach by using thread mills. So if a part requires threading, we first drill the hole to the correct diameter and then the thread mill cuts the threads. This allows us to produce threaded holes within the machine, saving set up time and costs. Using a single toolset, we can cut UNC and UNF threads from #2 up to 1/2 in. as well as metric threads ranging from M2 to M12.

as machined view dfm feedback
Using the as-machined view within your quote, you can identify any features that may be difficult to mill and understand exactly how your final part will look before it’s manufactured.

Cutting cylindrical features and non-cylindrical features within a single machine is another way we reduce cycle time. For geometries with external threads, such as a screw, we will turn those parts in a CNC lathe that’s equipped with live tooling. This is a lathe that includes end mills for milling non-cylindrical features. A common application of turning with live tooling is hex bolts or cylindrical parts with slots and holes.

An undercut is any feature that a mill is unable to reach. Some machine shops will have undercutting end mills or create a custom tool in some cases. Our toolset doesn’t includes tools for milling undercuts, but we can mill any off-axis features with our 3+2 or 5-axis indexed machining capabilities.

Machining Resources

If you have questions about your design and whether our toolset can accommodate it, it’s best to upload a part. You’ll receive design analysis, which includes an as-machined view that shows exactly what your part will look like when it comes out of the mill. If you just want to get an idea of how our design analysis works, check out a sample quote for machining.

Having a conversation with one of our applications engineer is another way to determine if your design fits within our capabilities and any potential changes you can make to improve its manufacturability. Just email us at

And don’t rule out handling some post-machining work yourself. We can always partner with your internal machine shop by doing the initial cutting. Let’s say there’s a recessed feature with a corner that our end mills can’t quite get to, once you receive the part you can clean it up yourself and have it exactly as you need. This is a great way to get parts as possible and keep costs down.