A machine tool is a machine for handling or machining metal or other rigid materials, usually by cutting, boring, grinding, shearing, or other forms of deformation.
Machine tools employ some sort of tool that does the cutting or shaping. All machine tools have some means of constraining the workpiece and provide a guided movement of the parts of the machine.
Thus the relative movement between the workpiece and the cutting tool (which is called the toolpath) is controlled or constrained by the machine to at least some extent, rather than being entirely “offhand” or “freehand”. It is a power driven metal cutting machine which assists in managing the needed relative motion between cutting tool and the job that changes the size and shape of the job material.
Examples of machine tools are:
- Broaching machine
- Drill press
- Gear shaper
- Hobbing machine
- Screw machines
- Milling machine
- Shear (sheet metal)
- Stewart platform mills
- Grinding machines
- Multitasking machines (MTMs)—CNC machine tools with many axes that combine turning, milling, grinding, and material handling into one highly automated machine tool
When fabricating or shaping parts, several techniques are used to remove unwanted metal. Among these are:
- Electrical discharge machining
- Grinding (abrasive cutting)
- Multiple edge cutting tools
- Single edge cutting tools
Other techniques are used to add desired material. Devices that fabricate components by selective addition of material are called rapid prototyping machines.
The worldwide market for machine tools was approximately $81 billion in production in 2014 according to a survey by market research firm Gardner Research. The largest producer of machine tools was China with $23.8 billion of production followed by Germany and Japan at neck and neck with $12.9 billion and $12.88 billion respectively. South Korea and Italy rounded out the top 5 producers with revenue of $5.6 billion and $5 billion respectively.