In mechanical engineering domain, Machine is defined as an assembly of mechanisms that are clustered to perform certain operations by utilizing electrical, mechanical, hydraulic, and/or pneumatic power. Total number of mechanisms exist within a machine may vary from just few to few hundreds! Accordingly size of a machine also varies. Some machines, irrespective of their size, are portable, for example, a hand drill (small machine) and a large mining crane both are portable.
What is a Machine-Tool?
The concept of machine tool is strictly restricted within the metal-working (or machining) field. By definition, a machine tool is a power operated and non-portable machine that can remove excess material from a pre-formed blank with the help of a suitable cutting tool. So a machine having following characteristics can be considered as a machine tool:
- It must be power driven (human operated machines are not machine tools).
- It must be non-portable (portability irrespective of size).
- It must have sufficient value (value in terms of capability and performance, not on the basis of cost).
- It can perform more than one type of machining or metal cutting operations.
- It utilizes a cutting tool to shear off excess materials from workpiece.
If and only if all the above five conditions are satisfied then a machine can be called as a machine tool. In fact, machine tool is the necessary (sometime mandatory) term to designate such machines which qualify all five conditions.
Examples of machine tool
- Lathe machine tool
- Milling machine tool
- Shaping machine tool
- Industrial drilling & boring machine tool, etc.
Therefore, all machine tools are basically machines but not vice versa.
Machine Tool and Cutting Tool—are they same or different?
Machine tool is completely different from a cutting tool (also called cutter). A cutting tool is a device having one or more wedge shaped and sharp cutting edges to facilitate shearing during metal cutting. So a cutting tool basically removes (shears off) material from workpiece. It is rigidly mounted on a machine tool. Machine tool facilitates all necessary motions and platforms required for cutting. For example, drilling machine is a machine tool, while the drill itself is a cutting tool.
Why lathe is not a machine?
By definition, any kind of lathe is a Machine! However, if you are in metal-working or machining field, then it is better (and mandatory) to say lathe is a machine tool. The term ‘Machine Tool’ has special significance in metal-working field and a center lathe or CNC lathe qualifies as a machine tool. Traditionally it is also believed that operation on lathe is mandatory for making any mechanical product even for making another machine tool. Due to its extreme capability, people associated with metal-working field love to designate lathe as a machine tool. Therefore, lathe is a machine tool, not a machine.