Lathe Machine is one of the most versatile and widely used machine tools all over the world. It is commonly known as the mother of all another machine tool. The main function of a lathe is to remove metal from a job to give it the required shape and size.

Components of Lathe Machine;                                                      

                                          A simple lathe comprises of a bed made of grey cast iron on which headstock, tailstock, carriage and other components of the lathe are mounted. The major parts of lathe machine are given as under:
1. Bed
2. Headstock
3. Tailstock
4. Carriage
5. Feed mechanism
6. Thread cutting mechanism

  Bed;

        The bed of a lathe machine is the base on which all other parts of the lathe are mounted. It is massive and rigid single piece casting made to support other active parts of the lathe.

Headstock;

                   The main function of the headstock is to transmit power to the different parts of a lathe. It supports the work and revolves with the work, fit into the main spindle of the headstock.

Tailstock;

                   

                The tailstock of the central lathe, which is commonly used for the objective of primarily giving an outer bearing and support the circular job being turned on centers. Tailstock can be easily set or adjusted for alignment or non-alignment with respect to the spindle center and carries a center called dead center for supporting one end of the work.

Carriage;

                    The carriage is mounted on the outer guide ways of lathe bed and it can move in a direction parallel to the spindle axis. It comprises of important parts such as apron, cross-slide, saddle, compound rest, and tool post
Feed Mechanism;
                                       The feed mechanism is the combination of different units through which motion of headstock spindle is transmitted to the carriage of the lathe machine. Following units play role infeed mechanism of a lathe machine;

1. End of bed gearing
2. Feed gearbox
3. Lead screw and feed rod
4. Apron mechanism
                                        The gearing at the end of bed transmits the rotary motion of headstock spindle to the feed gearbox. Through the feed gearbox, the motion is further transmitted either to the feed shaft or lead screw, depending on whether the lathe machine is being used for plain turning or screw cutting. The feed gearbox contains a number of different sizes of gears.
                                       The feed gearbox provides a means to alter the rate of feed, and the ration between revolutions of the headstock spindle and the movement of carriage for thread cutting by changing the speed of rotation of the feed rod or lead screw.
                                       The apron is fitted to the saddle. It contains gears and clutches to transmit motion from the feed rod to the carriage, and the half nut which engages with the lead screw during cutting threads.

Thread Cutting Mechanism;

                                       The half nut or split nut is used for thread cutting in a lathe. It engages or disengages the carriage with the lead screw so that the rotation of the lead screw is used to traverse the tool along the workpiece to cut screw threads. The direction in which the carriage moves depends upon the position of the feed reverse lever on the headstock.
LATHE OPERATIONS;
                                 For performing the various machining operations in a lathe, the job is being supported and driven by any one of the following methods.
1. The job is held and driven by chuck with the other end supported on the tailstock center.
2. The job is held between centers and driven by carriers and catch plates.
3. The job is held on a mandrel, which is supported between centers and driven by carriers and catches plates.
4. The job is held and driven by a chuck or a faceplate or an angle plate.
                                        The above methods for holding the job can be classified under two headings namely job held between centers and job held by a chuck or any other fixture. The operations performed in a lathe can be understood by three major categories:
(a) Operations, which can be performed in a lathe either by holding the workpiece between centers or by a chuck are:
      1. Straight turning                            2. Shoulder turning
      3. Taper turning                                4. Chamfering
      5. Eccentric turning                          6. Thread cutting
      7. Facing                                           8. Forming
      9. Filing                                            10. Polishing
      11. Grooving                                     12. Knurling
      13. Spinning                                      14. Spring winding
(b) Operations which are performed by holding the work by a chuck or a faceplate or an angle plate are:
      1. Undercutting                                 2. Parting-off
      3. Internal thread cutting                   4. Drilling
      5. Reaming                                        6. Boring
      7. Counterboring                               8. Taper boring
      9. Tapping
(c) Operations which are performed by using special lathe attachments are:
      1. Milling                                              2. Grinding
         
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