Computer numerical control (CNC) is programmed code that represents instructions for precise movements to be carried out by machines. Indirectly, this code defines how to automatically create, produce, or transform a virtual object into a real one.
Based on this definition, a CNC machine must interact with a computer equipped with software that transforms numerical code into Cartesian coordinates. This allows the machine to work with a high degree of precision, just like a robot.
A CNC machine transforms raw material into a finished model through different methods, either by adding (additive) or removing (subtractive) material. The available techniques depend on the type of machine. A 3D printer or CNC milling machine are fine examples of additive and subtractive CNC machines, respectively.
Milling is the process of cutting and drilling material (like wood or metal). A milling machine, regardless of whether it’s operated manually or through CNC, uses a rotating cylindrical tool called a milling cutter. It is held in a spindle and can vary in form and size.
The main difference between a milling machine and any other drilling machine is the ability to cut in different angles and move along different axes. For this reason, there are several kinds of milling machines, which are designated by number of movement axes:
Now we know that a CNC milling machine is any milling machine controlled through a computer. Yet, apart from axis classifications, there are still several types of milling machines, whether manual or CNC:
For each machine, you can find different sets of tools that perform different cuts. Some bigger, more industrial machines can even change the tool mid-job.
Different tools are designed for different materials, and it’s important to choose the perfect tool for the job. Failure to do so could result in unwanted damage to the material, the tool, or both.
Let’s compare wood and steel: If you choose an overly strong steel tool to cut wood, you could end up losing the workpiece. Meanwhile, if you use wood tools for steel, you will certainly end up breaking the tool and the machine.
As stated earlier, the most basic tool is a milling cutter, which kind of resembles a drill bit, but with teeth designed to remove material in ways other than just drilling. Cutters can vary in shape and size as well as in teeth orientation and spacing.
Digital technologies and CNC milling machines allow for the resolution of many problems which cannot be easily solved using prior methods. The technology approaches the working process in a way that’s both more effective and more efficient.
For example, without a CNC milling machine machine, the process of cutting metal for car parts or even aerospace components would be much riskier. With the support of computer programs, one can access and create high definition designs that are easily converted into Cartesian coordinates. This process even helps lower the costs of prototyping!
But these technological machines aren’t only for industrial use. Here are a few other areas to which CNC milling can be applied:
There are also a wide range of (hard and soft) solid materials that a CNC milling machine can cut:
If you’re a hobbyist looking for further guidance, take a look at our article on how to choose the right material for CNC milling.
License: The text of "What is CNC Milling? – Simply Explained" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.
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