Lathe Machine: Definition, Parts, Types, Operations, Specifications, Pros & Cons [Notes With PDF]

Understanding the basics of metal lathe machines is important for individuals interested in manufacturing, machining, or DIY projects that involve shaping or turning of materials. In this article, I will explain in detail everything about Lathe Machines. We have also provided a PDF download link for the same

What is the History of Lathe Machine?

Lathe machine is known as the mother of all machines in the production sector. The metal lathes found their origination in the ancient Egyptian civilization while the modern metal lathe machines were first developed during the 18th century industrial revolution. The earlier lathe were hand or foot operated then transitioned to being steam operated to provide certain level of automation.

Further developments in the 19th century made these lathe machines more precise and versatile making them capable to produce complex parts. Shortly after the invention of electric motors they were introduced for lathe machines which lead to their wide application in the manufacturing sector. Today in the modern Era of 20th century the development of computer numerically controlled or CNC lathe machines have revolutionized the production sectors offering the highest precision and automation features.

Lathe Machine 3D Model

What is the Definition of Lathe Machine?

A Lathe Machine offers versatility which can be useful to shape and cut materials like metal, plastics, and wood. A lathe machine is a tool where the workpiece is rotated on its axis which allows the cutting tool to perform material removal operations on the workpiece and create desired shape. Lathe machines can be operated manually or using CNC technology. These Lathe machines are available in different sizes for different applications

They are vastly used in machining industries or manufacturing sectors for creating parts with precise dimensions and complex figures. The lathe machines of various parts like headstock, tailstock, bed, tool post, carriage, etc., and the types of lathe machines include turret lathes, engine lathes, wood lathes, and vertical lathes each with specific advantages and features.

Lathe Machine Parts & Function

Lathe machine consists of the below given common parts which are as follows

• Bed
• Headstock
• Tailstock
• Carriage
• Saddle
• Cross-slide
• Compound rest
• Tool post
• Apron
• Lead Screw
• Feed rod
• Chuck
• Main spindle
• Leg

All of these parts are explained in detail below.

Bed

The main foundation of the lathe machine is the lathe bed that supports the different parts of the machine like headstock, carriage, and tailstock. The lathe made is made up of steel or cast iron and have different shape and size depending on the application intended

The Lathe Bed has a long, rectangular-shaped structure bolted to the workbench. It serves to provide a stable and rigid platform for the movement of workpieces and cutting tools during machining operations. It is defined to be mostly flat and leveled to make sure the movement of cutting tools is always in straight line to obtain precise and accurate results.

The cutting tool is held by the carriage and performs movement along the length of the lathe bed guided by rails or a set of ways that are machined in the surface of the bed. Near the Headstock the tailstock is also mounted on the lathe bed which supports the opposite end of the workpiece. The lathe bed is designed to provide accuracy and stability during machining operations. They have a robust construction to be long lasting, durable, and withstand constant stresses and vibration produced during machining processes

Head Stock

The Lathe headstock is a vital part of the Lathe machine, rotating and supporting the workpiece during machining. It includes components like spindle, pulleys, motor, and bearings, typically positioned on the left side of the lathe bed.

The main functions of the lathe headstock are:

• Rotation of the workpiece: The workpiece is rotated by the spindle of the headstock at different speed which allow the cutting tool to give desired shapes.
• Support of the workpiece: The workpiece is supported by the bearing in the headstock to ensure that during any machining operation the workpiece remains stable for maximum precision.
• Transmission of power: The spindle is driven by the headstock motor with the help of various belts and pulley arrangements so that there is ample power transmitted to turn the workpiece.
• Provision of threading capabilities: In some lathes, the headstock can be used to cut threads on the workpiece using specialized attachments.
• Alignment of the workpiece: The headstock ensures that the workpiece is accurately aligned with the tailstock and other machining components of the lathe, allowing for precise machining operations.

Accessories mounted on headstock spindle:

• Three jaw chuck
• Four jaw chuck
• Lathe center and lathe dog
• Collect chuck
• Faceplate
• Magnetic chuck

Tail Stock

The tail stock is situated on the right side above the lathe bed.

It is used for the following:

• 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.

Carriage

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.

Carriage consists of the following:

• Saddle
• Cross-slide
• Compound rest
• Toolpost
• Apron

It provides three movements to the tool:

• Longitudinal feed-through carriage movement
• Cross feed-through  cross slide movement
• Angular feed-through top slide movement

Saddle

Saddle, 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.

Cross-slide

Cross-Slide is assembled on the top of the saddle. The top surface of the cross-slide is provided with T-slot.

Compound rest

Compound Rest 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.

Tool post

Tool Post 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
• Square head tool post
• Quick change tool post

Apron

An apron is a house of the feed mechanism. It is fastened to the saddle and hangover in front of the bed.

Lead screw

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.

Feed Rod

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

Chuck is used to holding the workpiece securely.

There are generally 2 types of chucks:

• 3 jaw self-centering chuck
• 4 jaw independent chuck

Main Spindle

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.

Leg

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

What are the 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.

Speed Lathe

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 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 metal 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.

Tool Room Lathe

The tool room 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

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.

Automatic 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. CNC Lathe 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 start operation without changing the code 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.

How are operations performed During Lathe machining?

A Lathe Machine consists of the following operation:

• Centering
• Facing
• Turning
• Chamfering
• Knurling
• Thread cutting
• Drilling
• Boring
• Reaming
• Spinning
• Tapping
• Parting off

In Lathe operation, the workpiece is mounted on the spindle and rotated at the desired speed. To create the shape we need to remove material by moving it along the length by making it come in contact with the workpiece. The carriage is moved along the bed to control the depth of the cut, and the cutting tool can be changed as required to perform different machining operations. Before continuing any operation in the lathe we have to load the job and center it on the head-stock spindle.

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

Straight turning

To produce a cylindrical surface by removing excess material from a workpiece we employ the straight turning operation which is performed in the following way

• 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 goes on until the job is finished.

Shoulder turning

A shoulder turning is called which has a different diameter to form a step from one diameter to another.

There are four kinds of shoulder.

• Square
• Beveled
• Radius
• Undercut

Rough turning

It is a process of removal of excess material from the workpiece in minimum time by applying a high rate of feed and heavy depth of cut. the depth of cut is around 2 to 5mm and the rate of feed is 0.3 to 1.5mm/revolution.

Finish turning

The finish turning operation needs high cutting speed, minimum feed, and a very small depth of cut to generate a smooth surface. 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.

Taper turning

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.

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 operation

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.

Knurling operation

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 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 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.

Boring operation

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 boring tool. The boring tool is also fitted on the tailstock.

Reaming operation

Reaming is the operation of sizing or finishing a drilled hole to the required size by a tool called a reamer. This tool is fitted on the tailstock.

Spinning operation

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.

Tapping operation

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

Parting-off operation

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 the following

• Swing is 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 ton.

An informative video about lathes

Video on different types of Lathe operations

Application of Lathe Machine

• Manufacturing: Employed for the production of small to medium-sized parts and another industrial processes. Other use cases are in the production of automobile components, components for machines, and other mechanical devices.
• Automotive: They are applicable in the automotive industry to produce different components, such as drive shafts, engine parts, brake discs, and more.
• Aerospace: Here lathe machines are used to produce landing gear, aircraft engineers, and other components.
• Construction: In the construction industry Lathe machines are used to manufacture various components, such as nuts, bolts, and other fasteners.
• Woodworking: The woodworking industry use lathe machine to create decorative furniture, wooden objects, etc.
• Jewelry: Lathe machines are used in jewelry making to produce custom pieces like rings, bracelets, necklaces and other jewelry items
• Medical: The health sector uses lathe machines to produce medical components such as orthopedic implants, surgical instruments, etc.

These are just a few examples of the many industries where lathe machines are used. The versatility and precision of lathe machines make them an essential tools for many different types of manufacturing processes.

Advantages of Lathe Machine

• Versatility: They are used to create intricate shapes and designs like cylindrical parts, tapered parts, etc. on material like wood metal and plastics
• Precision: Lathe machines produce accurate and precise components with very tight tolerances and have additional features such as power feeds, digital readouts, and automatic tool changers to maintain the standards specified for the product
• Efficiency: These machines are highly efficient and produce high-quality parts in the short time period. They are ergonomically designed for easy setup and operation
• Cost-effective: These machines are affordable and gives good ROI for even people who make custom components
• Customization: These Lathe Machines Offer a high degree of customization for users helping them meet their specific requirements like custom angles, threads, shapes, etc.

Disadvantages of Lathe Machine

• Limited Part Size: They are suitable for small parts and aren’t recommended for larger parts to be machined on it
• Limited Cutting Speed: They offer a limited cutting speed and aren’t suitable for titanium or hardened steel.
• High Maintenance: To Operate at peak efficiency they require regular cleaning and maintenance which can be expensive and time-consuming for some businesses that work at a fast pace
• Noise and Vibration: They can be uncomfortable for operators due to being noisy and producing large vibrations which can also effect the final quality of the product
• Operator Skill: They require highly skilled operator for operations that means the operator must have a good understanding of machine, tools and materials.

FAQ

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