CNC Machining Basics

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By Jeremy Losek, Nov 4th, 2022

CNC Machining Basics

CNC (Computer Numerical Control) Machining is a subtractive manufacturing process that involves using high speed, precision machines to remove plastic or metal from a blank block of material to create a part. As the name implies, these machines are controlled by a computer and use a variety of cutting tools. Machines commonly controlled in this manner include vertical milling machines, horizontal milling machines, lathes, routers, and grinders. 

The computers and control consoles used to operate the machines make CNC machining a unique manufacturing process. CAM (Computer Aided Manufacturing) programming instructions tell the machine how to move its cutting tools. The software works in conjunction with a CAD (Computer Aided Design) model of the part provided by the customer. The machines are programmed with CNC machining language, known as G-code, that controls machine features like feed rate, coordination, location, and speeds. The computer controls the exact velocity and positioning of the tools, resulting in a precise and repeatable manufacturing process.  

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CNC Machine Basics

CNC machines operate following the instructions in the CAD model. The CAD file is loaded into the CAM software. Tool paths are generated based on the geometry of the part. The software tells the machine how fast to spin the tool tip and where to move in a 3-, 4- or 5-axis coordinate system. A CNC machine is essentially a computerized sculptor. The machine removes material from a metal or plastic block much the same way a sculptor removes material from a slab of marble to reveal the statue within.

What are the Types of CNC Machines?  

There are several types of CNC machines. These machines typically fall into five categories that are classified by function; CNC milling machines, CNC lathes, CNC plasma cuter, CNC grinders, and CNC drilling machines. The differences between the machines come down to the type of cutting tool, amount of axes the tools can operate, and the material that can be cut. CNC milling machines can cut on up to five axes, making them ideal for manufacturing parts with complex geometries. CNC milling machines use a spinning tool tip to remove material from blank blocks.  CNC plasma cutters typically only operate on two axes. A plasma torch is the standard cutting tool used to cut parts out of flat stock like sheet metal. CNC lathes also cut on two axes. The metal or plastic block is spun at high speed while the machine applies the cutting tool to the spinning material. CNC lathes will make identical cuts wherever the tool is applied. CNC lathes are ideal for cylindrical parts. CNC drilling machines typically operate on two axes. CNC drilling machines are used to create holes in designated areas of the block or flat stock. CNC grinders operate in a similar manner to CNC milling machines. Material is removed from a blank block using a grinding tool. 

ICOMold by Fathom has a wide array of CNC machines and access to Fathom’s extended manufacturing network. Speak with the experts at ICOMold to see what kind of CNC machine is best suited for your next project.  

CNC Machining Advantages 

CNC machining has many advantages over other manufacturing processes. It is a more precise process than manual machining and provides exact repeatability. A computer controls the machine movement ensuring the machine tools can all move precisely and simultaneously on their axes to create complex, three-dimensional shapes. These complex geometries would be almost impossible with manual machining. CNC machining is the ideal manufacturing process for jobs that require a high level of precision or repetition. 

Learn more about Plastic CNC Basics. 

Learn more about Metal CNC Basics. 

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