A lathe machine is a machine tool used to rotate various workpieces about one axis to perform different operations such as facing, turning, cutting, taper turning, knurling, drilling, etc. It helps to make a finished object. The various individual lathe machine parts are contributing or in action to give you a finished product. These parts are made with high precision to get a better result on the machine. Its assembly is complex, and it has higher accuracy in every operation. This article gives you all information about the different parts of a lathe machine & its functions.
Table of Contents
Parts of a Lathe Machine Diagram
Lathe Machine Parts Names
- Lathe Bed
- Cross Slide
- Compound rest
- Lead Screw
- Feed Rod
- Thread cutting mechanism
- Chip Pan
- Cooling Devices
Lathe Machine Parts
1. Lathe Bed
The lathe bed is the rigid and robust part of the lathe machine. It is generally made of cast iron because it is hard and absorbs vibrations. It avoids deflection due to a heavy working load.
The headstock locates on the left side, and the tailstock is on the right side of the bed. The carriage rests on the bed and slides over the bed.
On the top of the lathe bed, guideways are there to slide the tailstock and carriage over it.
These guideways are accurately machined to make them parallel with each other and provide bearing and sliding surfaces for the tailstock and carriage to slide. It is high resistance to wear.
There are two types of guideways.
- Flat guideways
- Inverted V guideways
Flat guideways give a high bearing surface, minimum wear, and are easy to clean. Inverted V guideways offer better alignment and a better guide to tailstock and carriage. It helps to fall down the chips from the bed.
Headstock fixes on the left-hand side of the lathe bed. It helps to rotate different workpieces at different speeds with the help of a chuck. The spindle, chuck, gears, gear drive, speed, and feed selector are present inside the headstock casting.
The material of the spindle is nickel or carbon chrome steel. The centreline of the spindle and the centreline of the lathe are perfectly in alignment with each other.
It is hollow from the inside. So a long bar can pass through it. The front end of the spindle can hold the taper part.
There are two types of spindles.
The threaded design carries a driving plate, faceplate, and chuck, whereas a flanged one enables them to attach.
The spindle is required with two bearings in the headstock from both sides. It can be a ball, bush, or roller bearing, and its selection depends on the type of application, loads, speed, and accuracy.
Chuck is for holding the workpiece during the machining process. It can be able to hold workpieces of irregular shapes rigidly and quickly.
Chuck is attached to the backplate with a bolt, and the backplate is screwed to the spindle nose. It is necessary to have an accurate alignment of the chuck with the lathe axis.
Different types of chucks
Four Jaw Chuck-
Four jaw chuck has four jaws that slide in the slot to give good gripping for different shapes of workpieces. In some cases, each jaw can slide independently by rotating a screw.
With the chuck, we can clamp hollow parts from inside and outside. Gripping surfaces of four jaws simultaneously apply pressure on the outside diameter of the pipe for clamping.
Whereas, for clamping from the inside, outer gripping surfaces simultaneously apply pressure on the inside surfaces of the pipe.
Three Jaw Universal Chuck-
Universal chuck consists of three jaws simultaneously sliding in the slot to clamp the workpieces. We can reduce the distance between three jaws by rotating the key in the chuck slot.
This chuck is suitable for delivering quick grip in round, hexagonal, and similar shapes. It has less gripping capacity than four jaw chuck.
Air or Hydraulic operated Chuck-
It consists of a hydraulic or compressed air cylinder mounted on the backside of the headstock. During the clamping act, hydraulic oil or compressed air is forced through the valves to the cylinders.
So the piston slides into the cylinder, and these pistons connect to the jaws to get open and close.
These chucks are suitable for only ferrous metals. This type of chuck is appropriate for those metals which can not sustain pressure applied by the jaws of other types of chuck.
In most cases, an electromagnet is present to make a magnetic force to clamp the workpiece. When we switch ON the power, flux develops to create magnetic force.
During the removal of the workpiece, we can switch OFF the power. By using ‘keepers’, we can short the circuit and prevent the flux from passing through the workpiece.
It is suitable for holding long parts. These parts pass through the spindle and are attached to the collet from the front end of the spindle.
The shape of the collection is round, hexagonal, etc trusting on the type of workpiece. Collet has an external thread lengthwise.
During the fixing of collect into the spindle, a key is inserted in the chuck hole to engage the thread with the collet to get better fixing. By loosening the key, we can disengage the collet.
It is a combination of four jaw chuck and universal chuck. We can drag their jaws independently, or through some adjustment, we can move their jaws simultaneously.
It uses for holding shank drills or taps for respective operations.
Tailstock fixes on the right-hand side of the lathe bed. It gives backing to the workpiece during the machining operation and holds a tool during drilling, tapping, reaming, etc.
According to the length of the workpiece, we can slide tailstock on the guideways and adjust it at a specific distance.
In the barrel of the tailstock casting, the spindle is there to hole drilling, tapping, reaming, etc tools. The spindle can move outside or inside with the help of a hand wheel having a square threaded screw connected to the spindle.
To engage the square threaded screw with the spindle the bush is at the backside of the spindle with similar threads for providing good engagement. The front end of the spindle is in taper in cross-section for more suitable fixing of the tool.
By rotating a handwheel in a clockwise and anticlockwise direction, we can move the spindle with the tool in the fourth and back.
We can clamp the spindle at the desired length with a spindle clamp. To tie a tailstock at a specific position, the use of a locking lever is essential.
To remove the tool from the tailstock, we can rotate the handwheel to its extreme back position to touch the wheel screw to the backside of the tool to apply pressure.
A carriage is a combination of parts to guide, move, support, and control the motion of the cutting tool. It consists of the following parts.
The saddle is an H shape casting that fits the bed and slides along the guideways. The Cross slide and tool post is part of the saddle.
8. Cross Slide
It is a machined dovetail shape part that fits into the saddle to achieve cross-movement at a right angle to the lathe axis. With the handwheel of the cross slide, we can move the cross slide.
9. Compound rest
Compound rest mount on the cross slide, which has a circular dial of angle. Its function is to arrange compound rest at a specific degree to achieve cuts in angular and tapers.
With the compound rest handle, we can give motion. It is a manual operation to do. The compound rest handle has a micrometer guide to decide the depth of the cut.
Toolpost fix on the top of the compound rest to hold and adjust the tool. We can clamp the tool like the single-point cutting tool, knurling tool, etc to do the operation.
The apron contains gears, levers, clutches, etc in the operation of the carriage. It plays a primary role in automatic feeds.
By employing the split nut with the lead screw, we can construct internal or external threads on the object. Handwheel of the apron help to move the carriage forth and back path.
It is the power source of the lathe machine. When the motor turns ON, it transfers the rotating motion through a belt drive, chain drive, or gear drive to the headstock spindle.
Due to that chuck rotate at a specific speed.
13. Lead Screw
The lead screw is the square threaded long shaft. It only comes into operation during thread cutting. It gives automatic linear motion during the thread-cutting process.
During ideal conditions, it provides motion during boring and turning operations.
14. Feed Rod
The feed rod helps to transfer motion from the lathe spindle to the apron assembly by the feed rod. There are so many gear arrangements there to transmit movement.
Feed rods help during turning, facing, and all other operations on the lathe machine by giving motion to the carriage.
15. Thread-cutting mechanism
This mechanism operates by the half-nut mechanism. This mechanism engages or disengages the carriage with the lead screw. The closing of the half nut allows the carriage to move at a fixed distance.
Split nut using only during thread cutting, not for other operations.
16. Chip Pan
It is for collecting chip formations during various operations on the lathe machine. It is at the base of the lathe machine.
It is present inside the headstock. It offers variation in speed with a geometric ratio as per requirement by moving a lever.
18. Cooling Devices
During the operations on the lathe machine, a cooling agent is necessary to reduce heat formation. So cooling water pump sprays the cooling medium during the process to reduce heat and remove chips from the working area into the chip pan.
On the leg, the whole mass of the machine is balanced. These legs are bolted to the foundation with bolts to transfer machine vibrations to the ground. It is crucial to passing a certain amount of machine vibrations to the earth for better stability.
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Thread cutting mechanism