A lathe Machine is a Production Machine tool. Here today we will study the Definition, Parts, Operation, and Specification of Lathe machines.
You can download the whole document in a PDF format, I will add the PDF download link at the bottom of this article.
So let me give you an introduction to the lathe machine tool.
Lathe Machine Introduction:
The Lathe was invented by Jacques de Vaucanson around 1751.
The Lathe Machine is an ancient tool. The very early stage of this machine was developed around 1300 BC at that time there were not developed so many parts except the headstock and Tailstock. But during the industrial revolution Metalworking lathes evolved into heavier machines with thicker, more rigid parts.
Between 19 and 20 centuries the electric motor replaced line shafting as a power source.
Then in 1950, servomechanism is applied to control lathes and other machine tools by numeric, Direct numerical control machine.
The Lathe is the most versatile machine tool among all standards of machine tools.
Nowadays the manually controlled machine exists like a CNC machine and even with the help of a feed mechanism the lathe machine operates manually.
Lathe Machine Definition:
A lathe machine is a machine tool that is used to remove metals from a workpiece to give a desired shape and size. Lathe Machines are used in metalworking, woodturning, metal spinning, thermal spraying, glassworking, and parts reclamation.
The various other operations that you can perform with the help of a Lathe Machine can include sanding, cutting, knurling, drilling, and deformation of tools that are employed in creating objects which have symmetry about the axis of rotation.
There are several components of a lathe, later on, I discuss the most important Parts of the Lathe with their function. It is also known as the father of all standard machine tools.
The function of the Lathe is to remove the metal in the form of chips from a piece of work by mounting the same rigidly on a machine spindle and revolving at the required speed and the cutting tool is fed against the work either longitudinally or crosswise to make the work to the required shape and size.
Parts of the Lathe Machine and their functions:
So what are the Parts of a Lathe machine? A lathe machine tool consists of several parts like:
- Compound rest
- Lead Screw
- Feed rod
- Main spindle
Let me explain all these parts in detail.
Head Stock is situated on the left side of the lathe bed and it is the house of the driving mechanism and electrical mechanism of a Lathe machine tool.
- It holds the job on its spindle nose having external screw threads and an internally Morse taper for holding the lathe center. And it is rotating at a different speed by cone pulley or all geared drive. There is a hole throughout the spindle for handling long bar work.
- Head Stock transmits power from the spindle to the feed rod, lead screw, and thread-cutting mechanism.
Accessories mounted on headstock spindle:
- Three jaw chuck
- Four jaw chuck
- Lathe center and lathe dog
- Collect chuck
- Magnetic chuck
A separate speed change gearbox is placed below the headstock to reduce the speed in order to have different feed rates for threading and automatic lateral movement of the carriage. The feed rod is used for most turning operations and the lead screw is used for thread-cutting operations.
It is the base of the lathe machine. It is made of the single-piece casting of Semi-steel ( Chilled Cast Iron). The bed consists of two heavy metal slides running lengthwise, with ways or ‘V’ formed upon them and rigidly supported with cross girths.
- It is sufficiently rigid and good damping capacity to absorb vibration.
- It prevents the deflection produced by the cutting forces.
- It supports the headstock, tailstock, carriage, and other components of the lathe machine.
The tail Stock is situated on the right side above the lathe bed.
It is used for:
- Support the long end of the job for holding and minimizes its sagging.
- It holds the tool for performing different operations like drilling, reaming, tapping, etc.
- And it is also used for a small amount of taper for a long job by offsetting the tailstock.
The carriage is used to support, guide, and feed the tool against the job when the machining is done.
- It holds moves and controls the cutting tool.
- It gives rigid support to the tool during operations.
- It transfers power from the feed rod to the cutting tool through the apron mechanism for longitudinal cross-feeding.
- It simplifies the thread-cutting operation with the help of a lead screw and a half-nut mechanism.
It consists of:
- Compound rest
It provides three movements to the tool:
- Longitudinal feed-through carriage movement
- Cross feed-through cross slide movement
- Angular feed-through top slide movement
Generally, it is made up of ‘H’ shaped casting and it has a ‘V’ guide and a flat guide for mounting it on the lathe bed guideways.
It is assembled on the top of the saddle. The top surface of the cross-slide is provided with T-slot.
It supports the tool post and cutting tool in its various positions. It can be swiveled at any desired position in the horizontal plane. It is necessary for turning angles and boring short tapers.
It is the topmost portion of the carriage and it is used to hold various cutting tools or tool holders.
There are three types of tool posts commonly used and those are:
- Ring and rocker tool post
- Squarehead tool post
- Quick change tool post
An apron is a house of the feed mechanism. It is fastened to the saddle and hangover in front of the bed.
A lead screw is also known as a power screw or a translation screw. It converts rotational motion to linear motion. Lead Screw is used for Thread Cutting operation in a lathe machine tool.
The feed rod is used to move the carriage from the left side to the right side and also from the right side to the left side.
Chuck is used to holding the workpiece securely.
There are generally 2 types of chucks:
- 3 jaw self-centering chuck
- 4 jaw independent chuck
The spindle is a hollow cylindrical shaft through which long jobs can pass through it.
It is designed so well that the thrust of the cutting tool does not deflect the spindle.
Legs are carrying an entire load of a lathe machine tool and transfer to the ground. The legs are firmly secured to the floor by the foundation bolt.
Schematic diagram of the lathe machine:
Types of Lathe Machine
A lathe machine tool is used for removing the excess material from the workpiece to give the required shape and size to the workpiece.
So how many types of Lathe machines are there? Lathe machine has been categorized into the following types:
- Center or Engine Lathe
- Speed Lathe
- Capstan and Turret Lathe
- Tool Room Lathe
- Bench Lathe
- Automatic Lathe
- Special Purpose and
- CNC Lathe Machine
We are going to study each and every important point of these 8 different types of lathe machines.
Center or Engine Lathe Machine:
Center or Engine Lathe Machine is the most widely used lathe machine and still, it is, in every workshop, this machine is present.
Operations like Turning, facing, grooving, Knurling, threading, and more, such operations are performed on this type of machine.
The engine lathe machine has all the parts such as bed, Saddle, headstock, tailstock, etc. The headstock of an engine lathe is rigid and the tailstock is moveable which is further used to support an operation like knurling.
It can easily feed the cutting tool in both directions i.e. longitudinal and lateral directions with the help of feed mechanisms.
Center Lathe machines are driven by the gear mechanism or pulley mechanism.
It has three types of driven mechanisms, and those are Belt-driven, Motor-driven, and Gearhead type.
A speed lathe is also called a Wood Lathe.
As the name indicates “Speed” the machine works at high speed. The headstock spindle is rotating at a very high speed. The parts have like headstock and tailstock, but it does not have feed mechanisms like a center or engine lathe. The feed we provide is manually operated.
The speed ranges of this machine operated between 1200 to 3600 RPM.
The speed lathe is used for spinning, centering, polishing, and machining wood.
Capstan and Turret Lathe:
This is an advanced technology in the manufacturing industry.
The capstan and turret lathe machine is used for Mass production (large Quantity) and is a modified version of the engine lathe machine.
This machine is used where their sequence of operation is performed on the workpiece, there is no alternative operation performed on this machine.
These machines were provided by a hexagonal turret head instead of the tailstock in which multiple operations (Turning, facing, boring, reaming) were performed in a sequence without changing its tool manually, after each operation the turret rotated.
It also consists of three tool posts. It requires more floor space than other lathe machines.
Capstan and turret lathe is used for only large jobs.
The main advantage of using a capstan and turret lathe is even less skilled operators can do a job.
Tool Room Lathe:
The toolroom lathe machine operates to speed up to 2500 rpm.
The parts are almost the same similar to the engine lathe machines but the parts are built very accurately and should be arranged in proper sequence because this lathe is used for highly precious work with very fewer tolerances.
It is mainly used in grindings, working on the tool, die gauges, and machining work where accuracy is needed.
Bench lathe machines are mounted on the bench.
This type of lathe machine is small in size and use for very small precision work. It has all the similar parts to the engine lathe and speed lathe.
As the name indicates “Automatic lathe” performs work automatically.
Standard lathes have some drawbacks i.e. they are not used for mass production. But automatic lathes are used for mass production. Some mechanisms are responsible for its automation in it.
Here there is no need to change the tool manually because it changes automatically.
Having this machine the main advantage is that a single operator can handle machines more than 4 to 5 machines at a time.
These types of lathes are high-speed and heavy-duty.
Special Purpose Lathe:
As the name indicates “special purpose lathe” the machine performs special types of operations which can not be performed on standard and other machines.
It is known for the heavy-duty production of identical parts.
Some examples of special lathes include Vertical lathes, Wheel lathes, T-lathe, Multi Spindle lathes, Production lathes, Duplicate or tracer lathes, etc.
The wheel lathe is used for machining journals and rail rods. It is also used for turning the threads on locomotive wheels.
The “T -lathe” is used for machining rotors for jet engines. The axis of the lathe bed is at right angle to the axis of the headstock spindle in the form of a T.
CNC Lathe Machine:
CNC stands for Computerized numerically controlled.
This is widely used as a lathe in the present time because of its fast and accurate working. It is one of the most advanced types.
It uses computer programs to control the machine tool. Once the program is fed into the computer as per the program it starts operation with very high speed and accuracy.
Even do preplanned programmed machine is there in which once code is set for the various operations it can starts operation without changing the code in the next time.
A semi-skilled worker can easily operate this after the initial setup is done.
These types of lathes are also used for mass production like capstan and turret but there is no programmed fed system.
The components manufactured by these lathes are very accurate in dimensional tolerances.
Now discuss the operations performed in a Lathe
A Lathe Machine consists of the following operation:
- Thread cutting
- Parting off
Before continuing any operation in the lathe we have to load the job and center it on the head-stock spindle.
In lathe operations, the headstock spindle holds the job and it rotates at the same speed as the spindle. The carriage holding the tool on the tool post, also the carriage gives the tool post moves longitudinally or crosswise direction to give the desired feed on the job.
These two motions (longitudinally and crosswise) help to remove the chips in the metal and give the proper shape to the job.
The Lathe is such a versatile machine that it can produce another lathe.
It is tough to mention which operations are not performed in a lathe machine tool, though we discuss some important lathe operations in detail.
Centering operation in the lathe:
We use this operation for producing a conical hole in the face of the job to make the bearing support of the lathe center when the job is to hold between two centers. (Head-stock and Tail-stock).
Facing operation in the lathe:
Facing operation is for making the ends of the job produce a smooth flat surface with the axis of operation or a certain length of a job.
In this operation,
- Hold the job on the Head-stock spindle using a Three or four-jaw chuck.
- Start the machine on the desired RPM to rotate the job.
- Give a desirable feed on the perpendicular direction of the axis of the job.
Turning operation in the lathe:
The operation by which we remove the excess material from the workpiece to produce a cone-shaped or cylindrical surface.
There are several types of turning operations, those are:
- Straight turning
- Shoulder turning
- Rough turning
- Finish turning
- Taper turning
- Eccentric turning
This operation is done to produce a cylindrical surface by removing excess material from the workpiece.
It is done in the following ways:
- Mount the job with a suitable job-holding device and check the trueness of the job axis with the lathe axis.
- Hold the cutting tool on the tool post and set the cutting edge at the job axis or slightly above it.
- Set the spindle as per the desired feed.
- Give depth of cut as per finish or rough cut.
- Start the machining.
- Engage the automatic feed to move the carriage with the tool to the desired length, then disengage the feed and the carriage is brought back to its starting.
- The process is repeated until the job is finished.
A shoulder turning is called which has a different diameter to form a
There are four kinds of shoulder.
It is a process of removal of excess material from the workpiece in minimum time by applying a
the depth of cut is around 2 to 5mm and the rate of feed is 0.3 to 1.5mm/revolution.
The finish turning operation needs high cutting speed, minimum feed, and a very small depth of cut to generate a
In finish turning the depth of cut is around 0.5 to 1mm and the rate of feed is 0.1 to 0.3 mm/revolution.
First, let me give you an idea about the taper.
A taper is defined as a uniform decrease or increase in the diameter of a workpiece along with its length.
The operation by which a conical surface of the gradual reduction in diameter from a cylindrical workpiece is produced is called taper turning.
Taper turning methods:
A tapering form may be done by any one of the following methods.
- Taper turning by form tool
- By swiveling the compound rest
- Tail-stock set over method
- By taper-turning attachment
Let me discuss them in brief.
Taper turning by form tool:
It is used to form a short length of taper by using a form tool or broad nose tool.
Any increase in the length of the taper will require the use of a wider cutting edge which may destroy the workpiece due to the vibration and spoil the workpiece.
In this operation, the tool angle must be half of the taper angle.
Taper turning by swiveling the compound rest:
This method is used for turning steps and short tapers.
It is done as follows:
- Set the compound rest by swiveling it from the centerline of the lathe center through an angle equal to a half-taper angle.
- Clamp the carriage in place.
- After adjusting and setting the tool, feed is applied by the compound rest’s feed handle to complete the taper.
Tail-stock set-over method:
Set over of tail-stock from its center-line is done equal to half taper.
Job is held between the centers. The length of the workpiece will be long enough. Only a small taper on a long job is done by this process.
It is used for external taper only.
By taper turning attachment:
It is done in the following ways:
- The cross slide is first made free from the lead screw by a hinder screw.
- The rear end of the cross slide is then tightened with a guide block by a belt.
- Set the guide bar at an angle to the lathe axis. (Half taper angle)
- The required depth of cut is given by the compound slide at a right angle to the lathe axis.
Chamfering is used for beveling the end of a job to remove burrs, to look better, and to make a passage of the nut into the bolt.
This operation is done after thread cutting, knurling, and rough turning.
It is the process of producing a rough surface on the workpiece to provide effective gripping.
The knurling tool is held rigidly on the tool post and pressed against the rotating job so that leaving the exact facsimile of the tool on the surface of the job.
Thread-cutting operation :
It is the operation that is used to produce a helical groove on a cylindrical or conical surface by feeding the tool longitudinally when the job revolved between the two centers.
Tool setting for thread-cutting operation:
The tool should be set exactly to the height of the centerline of the job and at 90 degrees to the job.
A tool setting gauge is used for this purpose.
Feeding during thread-cutting operation:
It is done in two ways.
- The tool may be fed exactly at 90 degrees to the job axis but it does not have good cutting action because only the front end of the tool does cutting.
- The tool may be fed at an angle from 27-30 degrees at which the compound rest may be set so that the complete side of the tool is used for cutting action which gives a better polish on the threads.
Job speed during threading:
The job speed will be 1/3 to 1/4th of the job speed in turning operation.
Drilling is an operation by which we can make holes in a job.
In this operation, the job is rotated at the turning speed on the lathe axis and the drilling tool is fitted on the tail-stock spindle. And the tailstock is moved towards the job by hand feed.
In this operation, we can enlarge the diameter of the existing hole on a job by turning it inside with some farm tool known as a
The boring tool is also fitted on the tail stock.
Reaming is the operation for sizing or finishing a drilled hole to the required size by a tool called a reamer.
This tool is fitted on the tailstock.
In this operation, the job of this sheet metal is held between the former and the tail-stock center and rotates at high speed with the former.
the long round nose forming tool rigidly fixed on a special tool post presses the job on the periphery of the former. So the job is taken exactly the shape of the former.
This is a chipless machining process.
We use this operation for creating internal threads within a hole by means of a tool called tap.
Three taps are generally used in an internal thread.
- Taper Tap
- Second Tap
- Plug Tap
It is the operation of cutting off a bar-type job after completing the machining process.
In this operation, a bar-type job is held on a chuck, rotates at turning speed, and a parting-off tool is fed into the job slowly until the tool reaches the center of the job.
Specification of a Lathe:
A Lathe is generally specified by:
- Swing- the largest work diameter that can be swung for the lathe bed.
- The distance between the headstock and tailstock center.
- Length of the bed in a meter.
- The pitch of the lead screw.
- Horsepower of the machine.
- Speed range and the number of speeds of HS spindle.
- The weight of the machine is around a tonne.
I also wrote an article on Milling Machine: Definition, Parts, Types, Operations and Drilling machine you may check that too.
Video lecture on Lathe machine tool if you wish you can check this video for brief knowledge:
Video of different types of Lathe operations
Hey, now I want to hear from you. I hope you understand the definition, parts, types, operations, and specifications of a lathe machine.
In case you wanna read this type of article on the Shaper machine you can check this article for that “Shaper Machine: Definition, Parts, Types, and Operations“, also you can find your desired topic on this page: Manufacturing Technology, here you can find all the articles on Manufacture technology.
What are the different types of lathe operations?
Who invented lathe?
What are the different types of taper turning methods in Lathe?
What are the different types of turning?
Can I perform drilling operations in a lathe?
Is it necessary to do a centering operation before performing any operation in the lathe?
- Wikipedia (Lathe)
- Manufacturing process II by NPTEL
- Lathe machine by DM Skoglund, PS Petersen, RJ Grimm – US Patent 3,121,357, 1964