What is machining?
Imagine peeling an apple or when using a plane in carpentary. Skins are removed and chips are developed. Basically machining and/pr cutting is an operation where an object is machined into aparticular shape using a sharp edged blade.
When machining takes place the object being machined (the workpiece) and the sharp edge blade (the cutting edge) are subjected to severe impact and rubbing at the point of contact.
To make machining possible, it is essential that the cutting edge is harder than the workpiece material. Generally it is said that a cutting tool needs to be at least 3 times harder than the workpiece material.