Turned Process

Turned part include :i) Bolt ,ii) Shafts ,iii) Spindle ,iv) Washer.
Three motion involved in Lathe turning are
The rotating motion of the work piece is called ‘Cutting or main motion’. The speed at which the material is removed from work piece by the cutting edge is called ‘cutting speed’
The cutting tool moves forward at a uniform rate forming a continuous chip (Feed motion)
The turning tool is set to desire depth of cut( Adjusting motion)

STRAIGHT TURNING -The work pieces are given cylindrical shape by straight turning , in which cutting tool move parallel to the axis of the turning spindle.

FACING The work pieces are given plane surface by facing , in which cutting tool move perpendicular to the axis of the turning spindle.
TAPER TURNING:The work pieces are given taper shape by taper turning operation , in which cutting tool move at angle to the axis of the turning spindle.


Center lathe , engine lathe and longitudinal turning lathes are used interchangeably

HEAD STOCK In the head stock (Picture) the main spindle on the bearings transmit the rotary motion to the work piece.
In most cases spindles are hollow so as to guide the bar stock through
Bearing :plain bearing , thrust bearing , ball and roller bearing
Head of spindle is provided with a thread to fix chuck and also provided with tapered hole to accommodate centers
Spindle is driven by motor through gear train

CARRIAGE :Supports and carries cutting tool
Contains feed mechanism and its adjustment
Consists of saddle , cross slide , compound slide , tool holder and apron.
The saddle and the cross slide are either operated by feed shaft or the leadscrew

TAILSTOCK:Serves as a support for turning long work piece
Provided with MORSE taper to accommodate
center , twist drill, boring tool ,reamer
Tail stock can be offset for taper turning
BED :Carries all lathe parts
The carriage and tailstock move on the guide way which are usually V and flat shaped.
Turning tool can be made of unalloyed tool steel, alloy tool steel, cemented carbide and diamond tip
Shank serves the purpose of clamping
Tool point consists of cutting edges
Cut face is the surface on the work piece which is formed by the cutting edge of the tool
The machined surface is the surface of the work piece obtained by the cutting process



The top face is the surface on which the chip curls .
The clearance face is the surface of the tool point, directed against the cut face.
The clearance angle is the angle between top face and clearance face
The rake angle is the angle between normal of the cut face and the top face
Clearance ,wedge and rake angle add up to 90 degree
The primary cutting edge is the cutting edge on the feed side
The secondary cutting edge is the cutting edge subsequent to the primary cutting edge


The Plan angle is situated between the primary cutting edge and machine surface. When turning with large plan angle the thickness of the chip is small , the cutting pressure is ditributed on a short portion of the cutting edge , tool life shortened and vice versa.

The nose angle is enclosed between primary cutting edge and secondary cutting edge tool with small nose angle blunt quickly.

The inclination angle determine the position of the primary cutting edge towards the horizontal line

Type of cutting tool include roughing tool , finishing tool and side tools

Toolpost include ordinary tool post and four way tool post.

Cutting tools should be set at center to obtain optimun results .

Cutting Speed =22/7 *RPM *D cirmeferential length of chip cut in one minute , depends on 1) Work piece material,2) Cutting tool materials,3) Cross section of the chip , 4)Cooling ,5) Machine Design

Feed means longitidunal distance travel for one full turning of work piece

Depth of cut means amount of penetration into the work piece to obtain a desired size.

A Typical operation plan sequence for manufacturing of bolt are
1) Chucking
2)Roughing and finishing of 1st step
3)Turning to length and deburing of 1st step
4)Rechucking
5)Roughing , finishing , turning to length and deburring of 2nd step