A Brief Explanation of CNC Milling

IMAGE: CNC Machined Multi-tools

Engineers love initialisms, mostly because they make saying long or complex phrases more efficient.  In this case the engineers that coined the term CNC didn’t feel like repeating Computer Numeric Control over and over again.  In subtractive manufacturing techniques like Milling, the goal of the operator is to liberate the useful object from inside a block material by removing the surrounding useless material.  So how is this done?

If you breakdown the phrase you can glean the function of this technology.  At its most basic a CNC machine manipulates an end effector in an established coordinate system to perform a task set about by the operator who controls it using a computer. CNC machines are typically used in an industrial setting; however, a printer is a good example of a nearly ubiquitous CNC machine. In order for a printer to deposit ink on a piece of paper, it needs the instructions from an operator. The operator tells the computer what they want to print and the computer sends that information to the printer in a way the printer can understand.  There is an unbroken thread from operator’s thought to information on paper and this is the same as fabricating a part. 

A mill works in a similar manner to a printer; however, instead of depositing ink a mill removes material from a work piece by moving a rotating cutter.  In the case of our multi-tool, steel was precisely cut away from a solid block until a multi-tool was all that was left. This type of machining is what CNC does best.  When high precision is needed to make complex parts, like aerospace components and injection molds, CNC milling is used.  Watching the highly coordinated and repeatable movements can be hypnotic.

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1 Response

Braden Bills
Braden Bills

December 29, 2016

I’ve always wondered about CNC milling technology. It’s so interesting that it can coordinate the process so well! It’s like a printer, but for metal. http://www.aeromechanism.com/company.php

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