What is CNC?
Terminology, history and applicable materials
The main CNC machining processes
CNC as such can be applied in a huge variety of manufacturing processes and machinery. In this page we focus on machining operations that can be identified by their production of chips. This means the processes are substractive by nature and the equipment involved are oftentimes called cutting machine tools.
Referring to the page title, CNC machining can be defined as automatically and digitally controlled machining processes. Main machining processes include:
● Milling, where the spindle rotates removing material.
● Turning, where the cylindrical workpiece rotates while spindle is fixed removing the material
● Drilling, where a hole is cut into the workpiece
● Grinding, where a rolling, abrasive wheel removes light amounts of material
● Sawing where material is cut (into parts) with a blade.
● Finishing operations
- Filing that is about light amounts of material removing, combining grinding and sawing and is used mostly in deburring
- Polishing and brushing, where a smooth or shiny surface is created with abrasive process.
The above are often called as conventional machining and abrasive processes. There are many other operations such as EDM (electrical discharge machining) or laser or water-jet cutting within the category of material removing operations that are not discussed in this page. Sometimes machining operations are also combined with additive manufacturing processes in hybrid machines.
The main types of CNC machines
Given the machining operations context set above, the most typical CNC machine tools are:
- 3-, 4- and 5-axis milling machines, sometimes also called machining centers
- Turning machines
- Multitasking machines: turn-mills and mill-turns that combine a milling spindle and workholding for turning operations.
- Grinding and sawing machines
This lathe can also perform milling operations
When discussing the finishing and other supportive processes for machining, one can also add to the list various machinery or cells that are digitally and automatically controlled via PLC (programmable logic controller) such as deburring with a robot or can be considered to be CNC machines such as a marking machine.