·
Straight turning
·
Profiling
·
Tapers and Taper Turning
·
External grooving, etc.
2. Drilling
3. Facing
4. Boring
·
Taper Boring
·
Counter Boring
5. Knurling
6. Reaming
7. Chamfering
8. Parting
9. Threading
10. Filling
11. Polishing
12. Grooving
13. Forming
1. Turning
·
Turning is the operation of decreasing the
diameter of a workpiece to produce a cone-shaped or cylindrical surface as
shown in fig. above.
·
Simple single-point cutting tools are used for
turning operations.
·
Turning can be different types like
i.
Straight turning
ii.
Tapers and Taper Turning
iii.
External grooving, etc.
iv.
Profiling
I. Straight turning
·
The Straight turning produces a cylindrical
surface by removing excess metal from the workpiece.
ii. Tapers and Taper Turning
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·
A taper may be defined as a uniform increase or
decrease in the diameter of a piece of work measured along its length.
·
In a lathe, taper turning means producing a
conical surface by the gradual reduction in diameter from a cylindrical workpiece.
iii. External grooving
·
In external turning, the operations machine the
outer diameter of the workpiece.
Iv. Profiling
·
In profiling, the cut can vary with regard to
cutting depth, feed, and speed.
2. Drilling
·
Drilling is an operation of producing a
cylindrical hole in a workpiece by the rotating cutting edge of a cutter known
as the drill.
3. Facing
·
Facing is an operation of reducing the length of
a workpiece to produce a flat surface square with the axis.
·
A regular turning tool may also be used for
facing a large workpiece.
4. Boring
·
Boring is the operation of enlarging a hole or
cylindrical cavity to produce circular internal grooves.
·
Holes may be boring straight and tapered.
i. Taper Boring
·
Taper Boring is similar to the external taper
turning operation and is accomplished by rotating the work on a chuck or a face
plate and feeding the tool at an angle to the axis of rotation of the workpiece.
ii. Counter Boring
·
Counter Boring is the operation of enlarging a
hole through a certain distance from one end instead of enlarging the whole
drilled surface.
5. Knurling
·
Knurling is the process of embossing a
diamond-shaped pattern on the surface of a workpiece.
·
The purpose of knurling is to provide an
effective gripping surface on a workpiece to prevent it from slipping when
operated by hand.
6. Reaming
·
Reaming is the operation of finishing and sizing
a hole that has been previously drilled or bored.
·
The tool used so calls the reamer, which has
multiple cutting edges.
7. Chamfering
·
Chamfering is the operation of beveling the
extreme end of a workpiece.
·
This is done to remove the burrs, protect the
end of the workpiece from being damaged, and have a better look.
8. Parting
·
Parting is the operation of cutting a workpiece
after it has been machined to the desired size and shape.
·
This process involves rotating the workpiece on
a chuck or face plate at half the speed that of turning and feeding by a narrow
parting–off tool perpendicular to the axis by rotating the cross-slide screw by
hand.
9. Threading
·
Threading is an operation to produce a helical
groove on a cylindrical or conical surface by feeding the tool longitudinally
when the job is revolved between centers or by a chuck.
·
Threads can be produced either on the internal
or external surface of a cylindrical bar.
10. Filling
·
The filling is the finishing operation performed
after turning.
·
This is done in a lathe to remove burrs, sharp
corners, and feed marks on a workpiece and also to bring it to size by removing
a very small amount of metal.
·
The operation contains passing a flat single-cut
file over the workpiece which revolves at high speed.
11. Polishing
·
It is basically a surface-finishing operation to
improve the surface quality of the workpiece.
·
Polishing with successively finer grades of
emery cloth after filling results in a very smooth, bright surface.
12. Grooving
·
Grooving is the process of reducing the diameter
of a workpiece over a very narrow surface.
·
It is often done at the end of a thread or
adjacent to a shoulder to leave a small margin.
Grooving Operations are:
a. Square Groove
b. Round Groov
c. Beveled Groove
13. Forming
Forming is the process
of turning a convex, concave, or irregular shape.
Types of lathe machine
The Lathe machines are
classified according to their design and construction. Some of these are:
1.
Speed lathe machine
2.
Bench lathe machine
3.
Tool Room lathe machine
4.
Engine lathe or center lathe machine
5.
Special purpose lathe machine
6.
Automatic lathe machine
7.
Capstan and turret lathe machine
1. Speed lathe machine
·
Speed lathe is the simplest of all types of lathe in construction and operation.
·
It consists of a bed, a headstock, a tailstock,
and a tool–post mounted on an adjustable slide.
·
The spindle speed is about 4000 rpm.
·
They were named because of the very High Speed
of the headstock spindle.
2. Bench lathe machine
·
A bench lathe is a small lathe usually mounted
on a bench.
·
This is used for small and precision work.
3. Tool room lathe
machine
·
The tool room lathe is similar to an engine
lathe.
·
This lathe is mainly used for precision work on
tools, Dies, and Gauges, and in making work where accuracy is necessary.
·
It is used for making precision components in
the tool room.
4. Engine lathe (center
lathe)
·
The term” engine” is associated with the lathe
which is early driven by steam engines.
·
An engine lathe is also known as a reproductive
machine because of its production capabilities.
·
Engine lathes are an excellent tool that aids in
the creation of many modern tools.
Advantages
·
It is used for the mass production of products.
·
It is used for manufacturing cylindrical shapes
like steel and plastics.
Disadvantages
·
It is so very difficult to program in machine
language.
·
Poor service, corruption, and racial issues.
5. Special-purpose lathe
machine
·
Special Purpose lathes are used for special
purposes and for jobs that cannot be accommodated or conveniently machined on a
standard lathe.
6. Automatic lathe
machine
·
In the automatic lathe, the various operations
are automated like the change of the workpiece.
·
The working cycle is fully automatic that is
repeated to produce duplicate parts without the participation of the operator.
Advantages
·
During machine operation operator is free to
operate another machine.
·
More economy in floor space.
Disadvantages
·
Lots of considerations are taken on fixing the
setup.
7. Capstan and turret
lathe
a. Capstan Lathe
·
They have features of the basic lathe and have
short slide tail stock.
·
A Capstan machine is a processing machine used
for making the same parts again and again.
Advantages
·
The production rate is high.
Disadvantages
·
The heavily weighted workpiece cannot be
machined by a capstan lathe machine.
b. Turret Lathe
·
A turret lathe is a form of metalworking lathe.
·
It is used for the insistent production of
duplicate parts.
·
In a turret lathe, a longitudinally feedable,
hexagon turret replaces the tail stock.
Advantages
·
A turret lathe is used to machine the heavy and
long workpieces.
·
They take hexagonal heads or tool posts.
·
There is no need of changing the tool.
Disadvantages
·
They have manual indexes.
Lathe Machine
Accessories
Lathe machine
accessories are generally divided into two categories:-
·
Work Holding devices
·
Cutting Tool Holding device
1. Work Holding devices
·
The work-holding devices are used to rotate and
hold the workpieces along with the spindle.
·
The different work-holding devices are used
according to the shape, length, diameter, and weight of the workpiece and the
location of turning on the work. They are as follows:-
A. Chucks
·
A chuck is a specialized type of clamp used to
hold the workpiece.
·
Chuck is mounted on the spindle which rotates
within the headstock.
Types of chucks:
a. Three Jaw Chuck
b.
Four Jaw chuck
c.
Collect Chuck
d.
Spindle Chuck
e.
Magnetic Chuck
f.
Combination Chuck
g.
Air Operated Chuck
B. Face Plate
·
The faceplate is a circular disc and thread to
fit the nose of the lathe machine spindle.
·
They have radial plain and ‘T’ – slots for
holding the work by bolts and clamps.
C. Mandrels
·
The mandrel is a device which uses for holding a
hollow workpiece.
·
The mandrel is mounting between centers and work
revolves around it.
D. Centers
·
A lathe center is a tool that has ground to a
point to accurately position a workpiece.
·
There are two centers:-
a. Live center
·
A live center is a center that fits into the
headstock spindle and revolves with the work.
·
A live center is constructed so that the
60-degree center runs in its own bearing.
b. Dead center
·
The dead center is the center that used a tail
stock spindle and doesn’t revolve.
c. Half center
·
The half center is the center that is often used
in the tail stock for facing up to or for Turning close to the end of the work.
·
It cuts away almost to its point.
E. Driving Plate or
Catch Plate
·
A catch plate is a plane disc that is made up of
cast iron or steel.
·
They have a central
F. Carriage
·
A carriage is a device that Clamps around the
workpiece.
·
They allow the rotary motion of the machine's
spindle to transmit the workpiece.
·
There are two types of carriage:-
a. Straight Tail
Carriage
·
This is used for driving the work by means of
the pin provided on the driving plate.
b. Bent Tail Carriage
·
It fits into the slot of the catch plate to
drive the work.
c. Angle Vise
·
Angle vise is an angular adjustment on the base
to allow the operator to drill holes at an angle without tilting the table.
2. Cutting Tool holding
device
·
The cutting tool holding device is a device that
is used to hold the cutting tools.
·
The different cutting tool holding devices are
as follows:-
A. Tool Post
·
A tool Post is a device that holds the cutting
tool on a lathe and some other machine.
B. Collect
·
Collect is a device that is used to hold a
cutting tool in the spindle of a milling machine.
C. Drill Chucks
·
It is the most common device which is using for
holding straight-shank cutting tools.
·
There are two common types:-
a. Key Type
·
It has been loosened or tightened by a key.
b. Keys fewer Types
·
It has loosened or tightened by hand without the
key.
D. Drill Sleeves
·
Drill sleeves are used to adapt smaller Morse
taper shank tools to larger machine spindles.
E. Drill Socket
·
A drill socket is used to hold twist drills with
shanks.
·
They have used often an extension socket.
F. Straight Tool Holders
·
Straight is used for making cuts in either
direction and for general machining operations.
Specifications of Lathe
Machine:
A lathe machine is
basically specified by:-
1.
Swing is the largest work diameter that can be
swung for the lathe bed.
2.
The distance between the tailstock and the
headstock center.
3.
Bed length of the machine in a meter (m).
4.
The lead screw of the pitch.
5.
The horsepower of the machine.
6.
Number of speeds of HS spindle and speed range.
7.
The machine weighs in a tone.
Some keys points
1. Feed
·
The rate at which the cutting tool crosses the
workpiece in the direction perpendicular to the workpiece axis so-called feed.
2. Depth of cut
·
It is the perpendicular distance measured from
the machined surface to the UN–cut surface of the workpiece.
3. Cutting Speed
·
The speed at which the metal is removed from the
workpiece with the help of a tool so calls cutting speed.
Formula
Cutting
Speed = πdn / 1000
4. Grinding
·
Grinding is the operation of removing metal in
the form of minute chips by feeding the work against a rotating abrasive wheel
so-called a Grinding wheel.
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