CNC milling is an automated, subtractive manufacturing technology designed to remove material in a controlled, pre-programmed manner to produce parts. Almost any material can be processed using CNC milling, including  metal, plastic, and wood. CNC mills require specialized operators, but once programmed, they can produces parts without continuous supervision. Engine blocks, gears, brackets, and various other components are produced with CNC mills.

A quick note on CNC milling vs CNC turning: CNC milling works by a moving tool across a stationary workpiece, whereas CNC turning rotates the workpiece, and a stationary tool does the cutting.

The CNC Milling Process

A CNC mill introduces a cutting tool into a stationary workpiece, automatically driving the tool through the material as the tool spins. Below is the basic workflow for CNC machine milling:

Design: The part is designed with 3D CAD (Computer-Aided Design) software using relevant DFM.You can check out our free CNC Design Guide  for some expert tips on designing your next CNC milled part. 

2. CAM: Once the CAD design is complete, it must be processed using CAM (Computer-Aided Manufacturing) software. CAM helps convert the 3D model into a set of instructions to tell the machine how to make it — i.e. which cutting tool to use when, the speeds and feeds, when to engage coolant, and when to probe specific features. Some may know these instructions as G-code for CNC machining, or have programmed CNC machine tooling and table positioning based off a coordinate system. Thankfully, this programming is mostly automated with CAM software.

3. Machining: The output from the CAM software is then loaded into the CNC machine, the workpieces (raw materials) are loaded into fixtures, and the CNC milling takes place. After the parts are finished, they’re unloaded from the CNC milling machine for assembly, consumer delivery, or post-processing.