Turning Tools and their Geometry

Turning Tools and Their Geometry

Cutting tools, used on lathes to cut away material from the work piece and bring the required shape, are called turning tools. These are generally single point tools, means; they have only one cutting edge. Different types of turning tools are used for different operations.

Turning Tool Working

General Nomenclature of Turning Tools

Geometry of a Turning Tool

Some commonly used Turning Tools

1.     Side Cutting Tool

It is also known as Knife tool, this tool is mainly used when a square shoulder is required on the work piece. This is an orthogonal cutting tool cuts, a nose radius of 0.5 to 1 mm should be given. A larger nose radius may cause chattering and vibration of the work piece and therefore not advisable for finishing long slender work pieces.

2.     Roughing tool

This is called a roughing tool, because it can be remove more material for the same tool life of a side cutting tool but it can be used for finishing also. This is an oblique cutting tool, Therefore it produces a third component of the cutting force which is directed along the radius of the work piece, which may tend to push the work piece away. This may cause chattering and vibration on thin and long work pieces, and spoil the finish. If this tool is made with 45^○ approach angle, it can be used advantageously for chamfering also which saves a lot of time.

3.     Recessing Tool

Also Called as Grooving tool, this tool is used for turning recesses or grooves. For this purpose it is fed right angular to the axis of the rotating work piece. Length of the cutting edge is made equal to or less than the width of the recess. The operation of grooving is done at a slower speed than longitudinal turning.

4.     Parting off Tool

This is similar to recessing tool except that is approach angle to ensure that the piece is cut off without leaving projection.

5.     Threading Tools

The point of the tools is accurately ground to the shape of the thread which they have to cut and with zero rake angle. Due to the zero rake angle, the form of the tool is not changed even after repeated re-sharpening. However, for roughing, rake angle may be given, but finishing cuts must be made with a tool having zero rake angles.