Turning is a form of machining, a material removal process, which is used to create rotational parts
by cutting away unwanted material. The turning process requires a turning machine or lathe, work piece,
fixture, and cutting tool.
Feed: It is used to describe the distance the tool moves per revolution of the work piece. For softer material
a feed up to 0.25mm per revolution may be used. For tougher material a feed upto 0.10mm per revolution is
used. A finer feed is required and recommended for better finishing.
Cutting speed:All material has an optimum cutting speed. It is defined as the speed at which a point on the surface
of the work passes the cutting or point of the tool and is normally given in meters/min.
Cutting speed is calculated by ;
Where; D = Diameter of work piece, N = Speed in rpm, V = Cutting speed in meter/min
Depth of cut:It is the measurement of how wide and deep the tool cuts into the workpiece. A large radial depth of
cut will require a low feed rate, or else it will increase the load on the tool and reduce the tool life.
Nose Radius:Nose radius makes the cut smoother and finer as it can overlap the previous cuts and eliminates the
peaks and valleys that a pointed tool produces. Having a radius will strengthen the tip, a sharp tip point will
Aspects of Machining Performance:The above cutting parameters such as speed, feed depth of cut and nose radius influences many
aspects of machining performance. They are as follows:Material Removal Rate (MRR):MRR is defined as the material removed per unit time. Speed, feed and depth of cut together
determine the material removal rate.
MRR = (V) × (f) × (d) (mm3)/sec
Where; V = speed in mm/sec, f = feed rate in mm, d = depth of cut in mm Material Removal Rate can also
be found out using experiments. It is the ratio of difference of initial weight and final weight to the time
Types Of Turning Operations
Face turning or facing