Cutting Tools Used in Lathe

A number of cutting operations are performed on a lathe machine. Therefore, various cutting tools are used in lathe such as left-hand and right-hand turning tools, facing tools, threading tools, parting-off tool, etc., as shown in Figure 19.10.

Figure 19.10 Various Cutting Tools Used in Lathe

19.5.6  Types of Operations on Lathe Machine

Following are the various types of operations performed on the lathe machines.

Turning

Turning is a metal removal process in which job is given rotational motion while the cutting tool is given linear (feed and depth of cut) motion. Different types of turning operations are mentioned as follows:

Straight Turning: It is the operation of producing a cylindrical surface of a job by removing excess material. In this operation, the job rotates and tool is fed longitudinally by giving the desired depth of cut (Figure 19.11).

Figure 19.11 Straight Turning on Lathe

Face Turning or Facing: Face turning is also known as facing operation. It is the operation of making the ends of a job to produce a square surface with axis of operation or to make a desired length of the job. In this operation job rotates and the tool advances in perpendicular direction to the axis of the job rotation (Figure 19.12).

Figure 19.12 Face Turning on Lathe

Shoulder Turning: If a job is turned with different diameters, the steps for one diameter to the other so formed, the surface is known as shoulder turning. There are several types of shoulder turning such as square, radius, bevelled, etc., as shown in Figure 19.13. It is also known as step turning.

Figure 19.13 Shoulder Turning on Lathe

Eccentric Turning: When a job having more than one axis of rotation, each axis may be parallel with each other but never coincides; turning of different cylindrical surfaces of the job is known as eccentric turning. In Figure 19.14, the job is first turned through centres C₁ − C₁ and then through centres C₂ − C₂.

Figure 19.14 Eccentric Turning on Lathe

Taper Turning: Taper turning is an operation in which taper cylindrical surface, i.e., cone type surface is produced as shown in Figure 19.15.

Figure 19.15 Taper Turning on Lathe

Taper on a cylindrical surface of a job can be produced by the following methods:

• Taper turning by swivelling compound rest: Job rotates on lathe axis and tool moves on angular path. It can be applied from any angle 0° − 90° for short length of taper up to 150 mm (approximate) . It is used for shorter length and steeper angle. Here, D_l and D_s are larger and shorter diameters, l is length of the job, and α is angle of taper.
• Taper turning by off-setting the tailstock: Job rotates at an angle to the lathe axis and the tool travels longitudinally to the lathe axis. Any angle 0° − 8°, long job of smaller diameter can be turned by this method. It is also used for internal taper turning.
• Taper turning attachment: Job rotates on lathe axis and tool moves in guided angular path. Long jobs of steeper angle of taper (0° − 12°) can be done by this attachment. Guide rail is set as per angle of taper. It is applied for mass production.
• Taper tuning by a form tool: Job rotates on lathe axis and tool moves crosswise direction, perpendicular to the lathe axis. Very small length of taper and any angle 0° − 90°. Tool itself designed as per requirements. It is used for mass production for Chamfering on bolts, nuts, bushes, etc.
• Taper turning by combination fed: Job rotates on lathe axis and tool travels on resultant path, for any length and any angle. Taper angle is to be determined by trial and error method. It is applied by hand feeds by combined feeding of tool (axial and perpendicular) for taper turning.