A number of types of machine tools gradually increased till mid 20th century and after that started decreasing based on Group Technology.
However, machine tools are broadly classified as follows:
1. According to the direction of major axis :
- horizontal center lathe, horizontal boring machine etc.
- vertical – vertical lathe, vertical axis milling machine etc.
- inclined – special ( e.g. for transfer machines).
2. According to the purpose of use :
- general purpose – e.g. center lathes, milling machines, drilling machines etc.
- single purpose – e.g. facing lathe, roll turning lathe etc.
- special purpose – for mass production.
3. According to the degree of automation
- non-automatic – e.g., center lathes, drilling machines etc.
- semi-automatic – e.g., capstan lathe, turret lathe, hobbing machine etc.
- automatic – e.g., single spindle automatic lathe, swiss type automatic lathe, CNC milling machine etc.
4. According to size :
- Heavy duty – e.g., heavy-duty lathes (e.g. ≥ 55 kW), boring mills, planning machine, horizontal boring machine etc.
- Medium duty – e.g., lathes – 3.7 ~ 11 kW, column drilling machines, milling machines etc.
- Small duty – e.g., table top lathes, drilling machines, milling machines.
- Micro duty – e.g., micro-drilling machine etc.
5. According to precision :
- Ordinary – e.g., automatic lathes
- High precision – e.g., Swiss-type automatic lathes
6. According to a number of spindles :
- Single spindle – center lathes, capstan lathes, milling machines etc.
- Multi-spindle – multispindle (2 to 8) lathes, gang drilling machines etc.
7. According to blank type :
- Bar type (lathes)
- Chucking type (lathes)
- Housing type
8. According to the type of automation :
- Fixed automation – e.g., single spindle and multispindle lathes
- Flexible automation – e.g., CNC milling machine
9. According to the configuration :
- Stand-alone type – most of the conventional machine tools.
- Machining system (more versatile) – e.g., a transfer machine, machining center, Flexible manufacturing system etc.