Introduction to Lathe Machine: A Comprehensive Guide for Machine Shop Operations, Slides of Mechanical Engineering

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Introduction of Lathe

Machine

(Machine Shop)

1

Introduction to Machine Shop

■ The shop where most of the work is performed

on different machines is called machine shop.

■ Different machines used in machine shop are:

• (^) Lathe Machine
• (^) Milling Machine
• (^) Shaper Machine
• (^) Planning Machine
• (^) Grinding Machine
• (^) Drilling Machine

Introduction to Lathe Machine

■ Lathe is a machine, which removes the

metal from a piece of work to the required

shape & size (cylindrical shapes)

■ The workpiece is placed between two

centers of machine, the driving center is

called head stock. The other one is a dead

center called tailstock.

Introduction to Lathe Machine

■ The job is securely and rigidly held in the

chuck or in between centers on the lathe

machine and then turn it against a single point

cutting tool which will remove metal from the

job in the form of chips.

■ Engine Lathe

Principal parts of an Center lathe

Principal parts of an Center lathe

1. Bed: The bed is a heavy, rugged casting and it

carries the headstock and tailstock for

supporting the work piece and provides a base

for the movement of carriage assembly, which

carries the tool.

2. Headstock: Headstock of a lathe is the power

source for the machine tool. The prime mover

(motor) is usually fitted at the bottom side and is

connected to the spindle of lathe using flat or V-

belt on stepped pulleys. Gears are also used.

Principal parts of an Center lathe

4. Carriage: The carriage is located between the

headstock and tailstock and serves the purpose of

supporting, guiding and feeding the tool against the

job during operation. The main parts of carriage are:

• (^) Saddle
• (^) Cross slide
• (^) Compound rest
• (^) Tool post
• (^) Apron

Principal parts of an Center lathe

5. Lead screw: A lead screw also known as a power

screw is a screw, moves the carriage by a precise

increment for every rotation of the screw. The lead

screw is made with square, acme, or buttress type

threads.

6. Quick-Change Gearbox: The quick-change

gearbox, containing a number of different sized

gears, provides the feed rod and lead screw with

various speeds for turning and thread-cutting

operations.

Lathe operations ■ Facing is the process of removing metal from the end of a work piece by using a single point cutting tool, to produce a flat surface. ■ (^) Turning is the process of removal of metal from the outer diameter of a rotating cylindrical work piece. Turning is used to reduce the diameter of the work piece, usually to a specified dimension.

Lathe operations ■ Centering (center drilling) is the process of providing a small tapered hole at end of a work piece by using centering tool, which can helpful to accommodate and support a running center in the tailstock. ■ (^) Drilling is the process of making holes at the end face of the work piece by using a drill bit, fixed with drill chuck, clamped at tailstock

Lathe operations ■ Parting is the process of cut off the work piece at a specific length by using a parting tool. It is normally used to remove the finished end of a work piece from the bar stock that is clamped in the chuck. ■ (^) Forming is a process of produces a convex, concave or any irregular profile on the work piece by using a form tool.

Lathe operations ■ Thread cutting is a process of cutting very accurate screw threads by using a single point cutting tool, which is the process of guiding the linear motion of the tool bit in a precisely known ratio to the rotating motion of the work piece ■ (^) Chamfering is a process of bevelling the extreme end of a work piece. This is done to remove the burrs and sharp edges from the extreme end of the work piece

Work Holding Devices

15

Three jaw chuck 16

• For holding cylindrical stock centered.
• The jaws are moved simultaneously by screwing one jaw. Four-Jaw Chuck
• (^) This is independent chuck generally has four jaws
• (^) Used to grip the workpiece of shape other than cylindrical.
• (^) Used to hold irregularly shaped parts
• (^) Off-center parts
• (^) Cams, Camshafts and Similar parts.