metal part

Design for Machining Toolkit

Get in-depth design advice to optimize your plastic and metal parts for CNC machining. Designing with machining in mind can accelerate production time and reduce production costs

Optimizing Part Design for Machining

There are many design considerations involved when creating CNC machined plastic and metal parts. You can design for cost, design for quality, design for assembly, or design for manufacturability, but navigating that landscape can be challenging, at times. At Protolabs, we provide automated design analysis on CAD models that highlights features in your part design that can be adjusted for manufacturability. It’s a great design resource to have at your fingertips. To keep those manufacturability advisories at a minimum and optimize your part design, we created this helpful kit detailing different CNC machining resources.

Designing for Machined Parts

Deep Features
Threads and Inserts

Navigating Critical Machining Advisories

Material Left Behind
Thin Walls
Holes That Can Be Threaded
Part Too Large

cnc stainless steel part

Designing for Machinability

CNC machining has been around for decades, and for good reason. It’s one of the fastest manufacturing technologies for prototypes and end-use parts. Want to learn how you can optimize your product development cycles with CNC machining? Our white paper shares how to design for this subtractive manufacturing process, select the best material for your application, and streamline new product development.

Design software

Optimizing your part for CNC Machining

Manufacturing both prototypes and production parts quickly and cost-efficiently is often a balancing act between on-demand CNC machining capabilities and an optimized part designed for those capabilities. When working with Protolabs’ milling and turning processes, there are a handful of important design considerations that can accelerate production time while reducing costs.

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Design Guidelines for Common Features


* Try adding steps to buttresses to stiffen your design. Watch out for deep, narrow pockets, or part features situated alongside tall walls. Cutter or workpiece vibration could cause deflection, and a loss of accuracy or surface finish.

** Generally, radii are a good thing, fillets spread loads well, sharp corners can act as stress raisers and can initiate fatigue cracks. We deburr every part, but if you are considering adding external radii to improve cosmetics and handling, a 45° chamfer is quicker to machine and considerably more cost effective.

Remember for CNC:

  • Internal corners—fillet or radii
  • External corners—chamfer

Any part that requires square corners will cost much more, as the only way to produce them is to burn them out with electro-discharge machining (EDM) or to cut slowly with extremely small tools.

Navigating Critical Machining Advisories

Get an online quote and manufacturing analysis today.

CNC silver parts

Enhanced Machining Capabilities with Our Protolabs Network 

Get anodizing, tighter tolerances, and volume pricing options through our network of manufacturing partners. You'll find plating (black oxide, nickel), anodizing (Type II, Type III), and chromate coating at scale; tolerances down to ±0.020mm; and cost-efficient machined parts at higher volume.

Try Protolabs Network