The Lathe machine

What is lathe??

• The lathe can be defined as a machine tool which holds the work between two rigid and strong supports, called centers, or in a chuck or face plate and revolves it.

• The chuck or the face plate is mounted on the projected end of the machine spindle(head stock spindle).

Types of lathes• According to different designs, different construction.1. Centre lathe –

(a) Bench lathe2. Tool room lathe3. Capstan and Turret lathe4. Special purpose:

(a) hollow spindle lathe(b) Gap bed lathe(d) Duplicating lathe

5. Automatic lathe

Component Description

DIFFERENT PARTS OF CENTRE LATHE :

Main six parts of Lathe Machine.• Bed• Headstock• Tailstock• Carriage• feed mechanism• Legs

1. Bed• part of lathe machine

which is the base of the machine.

• The all other parts are located on it.

• It carries all the weight of the machine.

• lathe bed being the main guiding member of the tool for accurate machining work.

• Condition1. sufficiently rigid to prevent deflection under

tremendous cutting pressure transmitted through the tool-post and carriage to the lathe bed.

2. It must be massive with sufficient depth and width to absorb vibration.

3. It must resist the twisting stress.4. The bed should be seasoned naturally to

avoid distortion or warp.

• Material• high compressive strength, wear resistant and

absorb vibration. • Cast iron alloyed with nickel and chromium

forms a good material suitable for lathe bed.The uses:-• It resists all the weight of machine’s parts. • It can resist the vibration of working machine.

2. Carriage

• Used to move cutting tool along lathe bed.

1. Saddle

2. The cross-slide3. compound rest4. Tool post 5. Apron

Saddle• The saddle is an H-shaped casting that fits

over the bed and slides along the ways. • It carries the cross slide and tool post.

The cross-slide• Mounted on top of saddle• Provides manual or automatic cross

movement for cutting tool.• The cross piece of the saddle is made at right

angles to the centre axis of the lathe.

The compound slide or compound rest• Mounted on the top of the cross-slide and has

a circular base graduated in degrees.• It is used for obtaining angular cuts and short

tapers as well as convenient positioning of the tool to the work.

The tool post• This is located on the top of the compound rest to

hold the tool and to enable it to be adjusted to a convening working position.

• Types of tool post 1 Single screw tool post2 Four bolt tool post 3 Open side tool post4 Four way tool postThe apron:-• The apron is fasted to the saddle and hangs over the

front of the bed, so the working of machine is vary fast.

• It contains gears, clutches and levers.• It carriage by hand and power feeds.

3. TAIL STOCKParts-Dead center-Tail stock spindle-tail stock spindle clamp-tail stock handle wheel-tail stock clamp lever- Offsetting screw

Tail stock• It is also known as loose head stock. • It is located on the inner ways at right hand end of

the bed. • To accommodate different lengths of work, the body

of the tail stock can be adjusted along the ways chiefly by sliding it to the desired position where it can be clamped by bolts and plates.

The main uses• It supports the other end of the work piece when it is

being machined between centers. • It holds a tool for performing operations such as

drilling, reaming, tapping etc.

4. Headstock

Headstock• Clamped on left-hand end of bed• Headstock spindle

– Hollow cylindrical shaft supported by bearings• Provides drive through gears to work-holding

devices-faceplate, or chuck fitted to spindle nose to hold and drive work

• Driven by stepped pulley or transmission gears

• Feed reverse lever – Reverses rotation of feed rod and lead screw

Work Holding Devices

Three jaw chuck

- For holding cylindrical stock centered.- For facing/center drilling the end of your job.

Four-Jaw Chuck

- This is independent chuck generally has four jaws , which are adjusted individually on the chuck face by means of adjusting screws

• Thin jobs can be held by means of

magnetic chucks.

Collet Chuck

Magnetic Chuck

Collet chuck is used to hold small workpieces

Thin jobs can be held by means of magnetic chucks.

Lathe Operations