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What is CNC Milling and What is it Used for?

What is CNC Milling and What is it Used for?

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What Is CNC Milling?

Computer Numerical Control (CNC) milling is a subtractive manufacturing process which uses a variety of rotating cutting tools to remove material from a workpiece. CNC mills consist of a multi-axis system (three, four, or five axes, depending on the part complexity).

CNC milling tools perform a machining process similar to drilling and cutting parts shapes out of a metal or plastic block of material but with incredible precision, holding dimensions to tolerances as tight as 0.002″. As the name suggests, the cutting tools are programmed and managed by a computerized manufacturing process, leaving no room for human error. This process can also be repeated as many times as desired to achieve a production run of identical parts, as fast as 4 days here at HLH.

3, 4 and 5 axis milling machines

  • 3-axis milling machines are the most common variety of milling machines. It operates on two axes (the X and Y axis), allowing for vertical cuts in any direction. Due to the limitations of the axes it operates on, there are restrictions to how complex a part it can produce.
  • 4-axis milling machines are more complex because they add the ability to rotate the x-axis, similar to a lathe.
  • 5-axis milling machines incorporate rotation in both the x and y axis. It allows you to shape aerospace structures, car components, medical devices, and pretty much anything else you can imagine.

CNC Milling vs CNC Turning

There are various CNC processes fit for different purposes, the two most common processes being CNC turning and CNC milling. Simply put, the difference between CNC turning and milling lies within the way the machine itself or the raw material moves. In CNC turning, the workpiece rotates against a cutting tool, whereas, in CNC milling, the material is held in place while the cutting tools rotate around it.

Due to the difference in movements, some processes will be more suited to milling or turning, respectively. For instance, as a milling machine has up to 5 axes of movement to manage- 3 linear ones in the X, Y and Z planes, as well as two rotational axes, it is better suited for creating more complex and intricate shapes.

Factors that will affect this include:

  • Shape and size of the part
  • Quantity
  • Material in use
  • Required finish
  • Budget


In deciding which CNC machining process is suited to what design, the biggest determining factor is the shape of the part followed by the size of the project.

Why Use CNC Milling For Your Project?

CNC milling — commonly used for automotive, aerospace, medical as well as in the production of robotics and automation — can also be used in tandem with CNC turning to add design features, such as flat faces, that are impossible to achieve otherwise.

If you are looking to create fast and repeated highly complex and intricate parts (from 1 to 10,000+ parts), CNC milling is an excellent choice. HLH’s CNC milling services can deliver custom machined parts, in both metal and plastic, four to five times faster than it takes using more traditional machining methods.

The Different Types of CNC Processes

Apart from CNC milling, there are several other common types of precision CNC machining processes. They include:


In order to take full advantage of the benefits of CNC milling, product designers and engineers must familiarize themselves with the process and considerations. Partnering with an on-demand digital manufacturer like HLH Rapid can be the ticket to faster, more effective design and production.

Drop us your designs today and our team of experts will create a DFM and provide suggestions on the most suitable process and how to optimize your designs.

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