Experiment No.: 01
Aim of the Experiment: –
To study about lathe machines, their classification and working processes.
Equipment Required: –
Lathe Machine.
Diagram: –
Theory: –
Lathe Machine is one of the oldest machine tools in the production machine. This machine is also known as the “mother of all machines.”
A lathe machine is a machine tool that removes the undesired material from a rotating workpiece in the form of chips with the help of a tool that is traversed across the work and can be fed deep into the work.
Lathe Machine Working Principle
A lathe works on the principle of rotating the workpiece and a fixed cutting tool. The workpiece is held between two rigid and strong supports called a center, in a chuck, or in a faceplate, which revolves.
Lathe removes the undesired material from a rotating workpiece in the form of chips with the help of a tool that is traversed across the work and can be fed deep into the work.
The main function of the lathe is to remove the metal from a job to give it the required shape and size.
Lathe Machine Types
There are 10 different types of Lathe Machines, and these are:
- Engine or Center Lathe
- Turret Lathe
- Toolroom Lathe
- Gap Bed Lathe
- Vertical Turret Lathe
- Speed Lathe
- Capstan Lathe
- Bench Lathe
- Hollow Spindle Lathe
- CNC Lathe Machine
Engine Lathe or Center Lathe
Engine Lathes’ name is derived from the fact that early machine tools were driven by separate engines or central engines with overhead belts and shafts.
The operations which can be performed by the Engine Lathe machine are turning, facing, grooving, knurling, threading, and many more operations that can be performed by it.
Turret Lathe Machine
It is a production machine that is used for the production of products on a large scale. It basically handles heavy-duty workpieces.
The distinguishing feature of this type of lathe is that the Tailstock is replaced with a hexagonal Turret.
Capstan Lathe Machine
It is similar to the Turret Lathe. Used for the mass production of light-duty workpieces.
It incorporates a capstan slide which moves on the auxiliary slide and can be clamped in any position.
This is best suited for the production of small parts because of its lightweight and short stroke of the capstan slide.
Speed Lathe Machine
This is the simplest form of the lathe and consists of a simple headstock, tailstock, and a tool post having no gearbox, lead screw, or carriage.
It has a very high speed of the headstock spindle. The speed of the spindle ranges from 1200 to 3600 rpm.
Tool Room Lathe Machine
Tool Room Lathe is a modern engine lathe equipped with all the necessary accessories for accurate tool room work. It is best suited for the production of small tools, dies, gauges, etc.
It is a geared head-driven machine with a considerable range in spindle speed and feeds. Its speed can range from very low to a very high speed of up to 2500 rpm.
Bench Lathe Machine
Bench Lathe Machine is a type of small lathe machine that has all the parts of the engine lathe and speed lathe.
It is mounted on a workbench and is used for doing small precision and light jobs.
Gap Bed Lathe
In a Gap Bed Lathe, a gap is provided over the bed near the headstock to handle the jobs having flanges or other protruding parts.
Mostly, a removable portion is provided in the bed so that when it is not required, it can be inserted.
Hollow Spindle Lathe
The Hollow Spindle Lathe allows you to cut and chamfer tubing with ease and efficiency. It can also be used to remove welds from existing shafts for the replacement of tubes, yokes, and splines.
Vertical Turret Lathe
Vertical Turret Lathe holds the workpiece vertically, which allows the headstock to sit on the floor and the faceplate to become a horizontal rotating table, analogous to a huge potter’s wheel.
This is useful for handling very large, heavy, short workpieces.
CNC Lathe Machine
Computer Numeric Control (CNC) is the most advanced form of lathe machine.
CNC Lathe Machine produces the most accurate products compared to other types of lathe machines.
In this machine, programs are fed to a computer system that controls the overall working of the lathe.
Lathe Machine Parts
The Lathe Machine consists of the following main parts:
- Bed
- Headstock
- Tailstock
- Carriage
- Saddle
- Cross Slide
- Compound Rest
- Tool Post
- Apron
- Chuck
- Feed Rod
- Lead Screw
- Spindle
Bed
The bed of a lathe machine is the base on which all the other parts of the lathe are mounted.
The bed is made from cast iron or nickel cast iron alloy and is supported on broad box-section columns.
A lathe machine’s “bed” is its main base structure that supports the headstock, tailstock, and carriage.
Headstock
The headstock is present on the left end of the bed. The main function of the headstock is to transmit power to the different parts of the lathe. It supports the main spindle in the bearing and aligns it properly.
Tailstock
Tailstock is a movable casting located opposite the headstock on the way of the bed.
The basic functions of the tailstock are:
- To support the other end of the work when being machined.
- To hold a tool for performing operations like drilling, reaming, tapping, etc.
Carriage
The carriage is located between the headstock and tailstock. The basic function of the carriage is to support, guide, and feed the tool against the job during operation.
Saddle
It is an H-shaped casting mounted on the top of the lathe way. It provides support to the cross slide, compound rest, and tool post.
Cross Slide
Cross slide is provided with a female dovetail on one side and assembled on the top of the saddle with its male dovetail. The top surface of the cross slide is provided with T-slots to enable the fixing of the rear tool post or coolant attachment.
Compound Rest
The compound rest is present on the top of the cross slide. It supports the tool post and cutting tool in its various positions. The compound rest is necessary for turning angles and boring short tapers and forms on forming tools.
Tool Post
The tool post is mounted on the compound rest. It is used to hold various cutting tool holders. The holders rest on a wedge, which is shaped on the bottom to fit into a concave-shaped ring (segmental type).
Apron
The apron is fastened to the saddle and hangs over the front of the bed. The apron consists of the gears and clutches for transmitting motion from the feed rod to the carriage, and the split nut which engages with the lead screw during cutting threads.
Chuck
Chuck is basically used to hold the workpiece, particularly of short length and large diameter or of irregular shape, which can’t be conveniently mounted between centers. It can be attached to the lathe by screwing on the spindle nose.
Four different types of chucks are most commonly used in lathe:
- Independent or four-jaw chuck
- Three-jaw universal chuck
- Collet chuck
- Magnetic chuck
Feed Rod
The feed rod is a power transmission mechanism used for precise linear movement of the carriage along the longitudinal axis of the lathe. In some lathe machines, instead of feed rods, lead screws are used.
Lead Screw
The lead screw is used mostly in the case when the threading operation is to be performed on a lathe. As we know, threading operation requires rotational movement of the job (workpiece) and the linear movement of the tool (tool post).
Spindle
Lathe spindles are used for machine-cutting of workpieces. They can also be referred to as workpiece spindles, as the workpiece is clamped via the chuck of the lathe spindle.
Different operations performed on lathe machine: –
The following different types of lathe machine operations are:
- Turning Operation
- Shoulder Turning
- Thread Cutting Operation
- Chamfering Operation
- Drilling Operation
- Counter Boring Operation
- Reaming Operation
- Tapered Turning
- Facing Operation
- Parting Operation
- Knurling Operation
- Boring Operation
- Countersinking Operation
Turning Operation:
Turning is a machining operation in which the diameter of the workpiece is reduced by removing the excess material from the outer diameter of the job (workpiece), which is nearly cylindrical or conical in shape.
Tapered Turning Operation:
Tapered Turning is a machining process in which the cylindrical jobs are machined to produce a conical surface.
Shoulder Turning Operation:
Shoulder Turning is used in the case where several diameters are to be turned on the workpiece. The surface forming the step from one diameter to the other is called the shoulder.
Facing Operation:
Facing is a process in which the end of the workpiece is being machined by the tool, which is at a right angle to the axis of the rotation of the workpiece.
Thread Cutting Operation:
Thread cutting is a type of operation in which the threads are cut on the internal and the outer surface of the workpiece as per the requirement.
Parting Operation:
Parting is an operation in which deep grooves are being made on the parent material to remove the specific portion from the parent material, resulting in dividing the workpiece into two or more parts.
Chamfering Operation:
Chamfering is the operation of beveling the extreme end of a workpiece. Chamfering is done usually after knurling, thread cutting, etc.
Knurling Operation:
The process of making the surface of the workpiece rough by embossing (impressing) a diamond-shaped regular pattern on the surface by making use of a knurling tool is called a knurling operation.
Drilling Operation:
Drilling operation is a type of machining operation that is used to remove the material from the workpiece by making use of a drill bit, which is held stationary in the tailstock, finally creating a hole in the workpiece.
Boring Operation:
Boring is an internal turning operation used for enlarging the existing holes by some amount.
Counter Boring:
Counter Boring is an internal turning operation used for enlarging the end of the hole.
Countersinking:
Countersinking is the operation of the conical enlargement of the end of the hole. It requires a large size drill bit than that required for the hole.
Reaming Operation:
It is a machining process that is done after drilling to make internal holes of a very accurate diameter. This operation helps to remove a very small amount of material from the holes which are already drilled.
Conclusion: –
To be written by student.