In this content,You can learn about operations of Lathe machine in production process.


 Operations on Lathe


The most common operations which can be carried out on a lathe are as follows:-


(1) Facing


(2) Plain Turning


(3) Step Turning


(4) Drilling & Reaming


(5) Boring


(6) Knurling


(7) Milling


(8) Grinding


(9) Threading


(10) Forming


(11) Taper Turning

  








Operations on Lathe in production process are in details:-


(1) Facing:-


Facing is the operation of machining the end of workpiece to make end flat and smooth and also to make the piece of the required length. This operation involve two steps. In the first step a rough facing operations is done by using a heavy cress feed an a deeper smaller depth of cut of about 0.5 mm is employed. In this operations tool move perpendicular to the axis of lathe.





(2) Plain Turning:-


Plain turning is the operation to remove excess material from the surface of or the outer diameter of a workpiece to obtain a finished surface and workpiece of reduced diameter. In this operation workpiece is either held in the chuck or between centres . The feed of the tool for plain turning operation is provided along the axis of the lathe ( longitudinal feed) either by hand or by power.


(3) Step Turning:-


Step turning operation produces various steps of different diameters in the workpiece. It is carried out in the similar way as plain turning.


(4) Drilling and Reaming:- 


Drilling is the operation of making a cylindrical hole in workpiece and Reaming is the operation of finishing the internal walls of drilled hole. These operations are done on lathe by holding the drills and reamers in the tail stock quill. The shanks of these tool are held in the tapered hole. The drill reamer is the fed by hand by rotating the hand wheel for the tail stock. The job is held in chuck or in other suitable device.





(5) Boring:-


Boring is the operation of enlarging the drilled hole. This operation involves the use of a boring tool or a bit mounted on a rigid bar held in the tool post and fed in the work by hand or power. Boring is done by moving the carriage towards the headstock.






(6) Knurling:-


In Knurling operations diamond shaped patterns are made on the surface of a workpiece to create a handgrip or roughened surface on a workpiece. In this operation the metal on the surface of workpiece is plastically displaced into a particular pattern with the help of a special Knurling tool which consists of one set of hardened steel dollars in a holder with the teeth cut on their surface in a definite pattern. 


The knurling tool is hold in the tool post and is pressed against the surface of the workpiece by cross feed. Knurling is done at the slowest speed available in the lathe.


(7) Milling:-


For milling operation, small milling cutters are held in headstock and revolved while the work is clamped in a vise mounted over the top of the compound rest. This operation is used only for small work. Milling operation can also be done by use of separate milling attachment. 


          The milling attachment consists of a vertical pillar to which an individual motor and a device to mount cutter on it is attached. Base of the pillar is fastened rigidly to the saddle in front of lathe and the unit carrying motor and the cutter can be moved vertically up and down by means of a screw and the hand wheel provided at the top of the pillar. The job is held  stationary between the centres and the milling cutter is moved longitudinally along it by operating the saddle.


(8) Grinding:-


Grinding is the process of removing material from the workpiece by the abrasive action of a revolving wheel on the surface of a workpiece in order to bring it to the required shape and size.


Cylindrical and internal grinding can be done on a lathe with a tool post grinder; which contains a spindle for mounting a grinding wheel and a motor for driving it. A  small wheel is used for internal grinding and a larger wheel is used for external grinding. 


    The tool post grinder is mounted on the compound rest in the place of tool post. For external grinding the workpiece is held in a chuck or between centres. For internal grinding the workpiece is held in a chuck or mounted to the faceplate. Tool post grinder is used for simple jobs like grinding mandrels or reamers, turning chuck jaws, sharpening lathe centres and milling cutters etc.


(9) Threading:-


Cutting helical grooves on the external cylindrical surface of the workpiece is called" Threading" . In this operation the workpiece is held in a chuck or between centres and the threading tool is fed longitudinally to the revolving work. The longitudinal feed is equal in the pitch of the thread to be out.








(10) Forming:- 


            Sometimes parts of such shapes are required to be machined which have neither cylindrical nor tapered surfaces, over all lathe. For machining these shapes special tools called" Form Tools" are used. Shape and size of the cutting edge of such a tool corresponds to the shape and size of the surface to be produced.







           Form surfaces can also be produced by combining cross and longitudinal feed or by the use of tracing or copying a template.


(11) Taper Turning:-


Sometimes it is required to provide conical shapes to the components, if their cross section is circular and if the components are flat it is required to provide a gradual reduction in their width or thickness along their length.
         

        The gradual decrease in diameter of a job of circular cross-section along its length or a gradual decrease in the width or thickness of a job of rectangular cross-section along length is termed as " a tapper".





                  For conical pieces the difference between the diameters of their ends is known as tapper and for flat pieces the difference between the widths or thickness of their ends is known as tapper. In taper turning a conical surface is produce by gradual reduction in diameter of a cylindrical workpiece.



Taper turning can be carried out on lathes by the following methods:-


(a) By compound rest method


(b) By using a form tool


(c) By setting over the tailstock


(d) By using a taper turning attachmen







Conclusion:-


You have learnt about operations of Lathe machine like turning, milling, drilling, boring ..etc in production process.