In the field of mechanical engineering, Machine is defined as an assembly of mechanisms that are clustered together 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, non-portable and valuable machine that can perform multiple machining operations by remove excess material from a pre-formed blank with the help of a suitable cutting tool. So a machine having following five characteristics can be considered as a machine tool.

• It must be power driven (human operated machines are not machine tools). The form of power at input to the machine tool can be either electrical, mechanical, hydraulic, pneumatic or a non-conventional one.
• It must be non-portable (portability irrespective of size). Thus machine tools are always firmly installed with the shop floor.
• It must have sufficient value (value in terms of capability and performance; not on the basis of cost).
• It can perform more than one machining or metal cutting operations.
• It utilizes a cutting tool to shear off excess materials from workpiece.

If and only if all of the above five conditions are satisfied then a machine can be called a machine tool. In fact, machine tool is appropriate (sometime mandatory) term to designate such machines that qualify all five conditions. Examples of machine tool include 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.

What is cutting tool and how it differs from machine tool?

Machine tool is completely different from the cutting tool (also called cutter). A cutting tool is a small 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 the machine tool in appropriate location. Shape and features of the cutting tool varies widely based on the required machining operation and intended performance.

Cutting tool cannot provide any motion required for cutting. All intended motions are provided by the machine tool. So cutting tool is mounted on a machine tool using suitable tool holding arrangements so that it can compress a thin layer of workpiece material to gradually shear it off in the form of chips for realization of material removal. For example, lathe is a machine tool, while the SPTT (single point turning tool) is a cutting tool. The following table displays several machine tools and typical cutting tools that can be mounted on corresponding machine tools.

Machine Tool	Cutting Tool
Lathe machine tool	Turning tool
	Threading tool
	Centering tool
	Drill
	Grooving and parting tool
	Knurling tool
Drill machine tool	Drill
	Boring tool
	Reamer
Milling machine tool	Peripheral mill
	Face mill
	End mill