The primary task of a lathe is to generate cylindrical workpieces. The process of machining a workpiece to the required shape and size by moving the cutting tool either parallel or perpendicular to the axis of rotation of the workpiece is known as turning. In this process, excess unwanted metal is removed. The machine tool useful in performing plain turning, taper turning, thread cutting, chamfering and knurling by adopting the above method is known as lathe. Schematic illustration of the components of a lathe Schematic illustration of a turning operation showing depth of cut, d, and feed, f. utting speed is the surface speed of the workpiece at the tool tip. (b) Forces acting on a cutting tool in turning. Fc is the cutting force; Ft is the thrust or feed force (in the direction ot teed); and Fr is the radial torce that tends to push the tool away trom the workpiece being machined. Manufacturing processes used during the making of the power shaft: Turning Turning in a lathe is to remove excess material from the workpiece to produce a ylindrical surface of required shape and size.
Straight turning The work is turned straight when it is made to rotate about the lathe axis and the tool is fed parallel to the lathe axis. The straight turning produces a cylindrical surface by removing excess metal from the workpieces. Step turning Step turning is the process of turning different surfaces having different diameters. The work is held between centres and the tool is moved parallel to the axis of the lathe. It is also called shoulder turning. Facing Facing is the operation of machining the ends of a piece of work to produce flat urface square with the axis.
The operation involves feeding the tool perpendicular to the axis of rotation of the work. Chamfering Chamfering is the operation of bevelling the extreme end of the workpiece. The form tool used for taper turning may be used for this purpose. Chamfering is an essential operation after thread cutting so that the nut may pass freely on the threaded workpiece. Grooving Grooving is the process of cutting a narrow goove on the cylindrical surface of the workpiece. It is often done at end of a thread or adjacent to a shoulder to leave a mall margin.
The groove may be square, radial or bevelled in shape. Thread cutting Thread cutting is one of the most important operations performed in a lathe. The process of thread cutting is to produce a helical groove on a cylindrical surface by feeding the tool longitudinally. But we did it manually using a die. Filling Filing is a final material removal process in manufacturing.