1. Shroff S.R. Rotary Institute Of Chemical Technology
Sub:-Manufacturing process-1
Question:-Enumerate operations carried out on lathe. Explain ‘setting of tailstock centre for taper turning’ operation and ‘thread cutting’ operation both with neat sketch.
prepared by:-Malaysinh Borasiya( )
Meet Bhatt( )

2. Operation performed on lathe:-
Operations, which can be performed in a lathe either by holding the workpiece between center or by chuck are:
(1) Straight turning (2) Shoulder turning (3) Taper turning
(4) Chamfering (5) Eccentric turning (6) Thread cutting
(7) Facing (8) Forming (9) Filing
(10) Polishing (11) Grooving (12) Knurling
(13) Spinning (14) Spring winding
Operations which are performed by holding the work by a chuck or a faceplate or an angle plate are:
(1) Undercutting (2) Parting-off (3) Internal thread cutting
(4) Drilling (5)Reaming (6) Boring
(7) Counter boring (8) Taper boring (9) Tapping

3. Taper turning by setting over tailstock:-
The principle of turning taper by this method is to shift the axis of rotation of work piece from original axis.
The amount of offset for a particular taper can be calculated by using the formula,
set over(offset)=L*[D-d/2L]
where L=total length of work piece
l= the length of taper
D= larger diameter of the work piece
d= smaller diameter of the work piece

4. Taper turning by setting over tailstock:-
The angle at which the axis of rotation of the work piece is shifted is equal to half angle of taper.
The tailstock is provided with a separate base and body, and are fitted together.
The tailstock body can be moved at right angle to the axis of the lathe.
Cutting tool is held in the tool post and is fed into work piece by rotating longitudinal slide wheel.
The slide moves parallel to the original axis of work piece and thus produces taper on the work piece.
This type of taper turning is used where work piece is long slender and taper angle is small.

5. Thread cutting:-
Thread of any pitch, shape and size can be cut on a lathe using single point cutting tool.
Thread cutting is operation of producing a helical groove on spindle shape such as V, square or power threads on a cylindrical surface.
The job is held in between centers or in a chuck and the cutting tool is held on the tool post.
The cutting tool must travel a distance equal to the pitch (in mm) as the work piece completes a revolution.

6. Thread cutting:-
The definite relative rotary and linear motion between job and cutting tool is achieved by locking or engaging a carriage motion with lead screw and nut mechanism and fixing a gear ratio between head stock spindle and lead screw
To make or cut threads, the cutting tool is brought to the start of job and a small depth of cut is giving to cutting tool using cross slide.

7. Thank you