What is lathe machine, give a classification of lathe machine.

Lathe machine-

 The lathe can be defined as a machine tool which holds the work between two rigid and strong supports called live center and dead center, the former revolves. A lathe basically consists of a bed to provide support, a head stock, a cross-slide to traverse the tool, a tool post mounted on the cross slide. The spindle is driven by a motor to obtain a range of speeds. The carriage moves over the bed guideways parallel to the workpiece and the cross slide provides the transverse motion. A feed shaft and a lead screw are also provided to power the carriage and for cutting the threads respectively. Lathe removes undesired material from a rotating work piece in the form of chip. The cutting tool is rigidly held and supported in a tool post and is fed against the rotating workpiece.  While the workpiece rotates about its own axis the tool is made to move either parallel to or at an inclination with the axis in doing so it produces cylindrical surface if it is fed parallel to the axis or will produce a tapered surface if it is fed at an inclination.

Lathe machine

                      

Principal of lathe

                        

what-is-internal-combustion-engine.                          

Types of lathe machine.

(1). Low production type lathes-

         (a) Bench Lathe - A bench lathe is a very small lathe mounted a separately prepared bench or cabinet. Bench lathe is generally used for small and light jobs, requiring precision work. It possesses almost all the parts which a larger lathe carries and thus capable of performing almost all the operations which a larger lathe can do.

          (b) Speed ​​Lathe - A speed lathe is the simples to all types of lathes. It is named so because of the very high rotational speed of spindle up to 4000 r.p.m. Speed ​​lathes have no gear box, carriage and the lead screw.  The tool which rests on a support, is fed and operated adjusted by hand. 

          (c) Engine Lathe or Center Lathe - An engine lathe or center lathe is a general purpose turning machine. Its main components are the bed, tailstock, headstock, carriage and quick change gear box (fig). The headstock located at one end of the lathe bed contains gears or pulleys to drive the workpiece at different speeds and is operated by an electric motor. The tailstock, mounted at the other end of the bed can be moved towards or away from the headstock to accommodate workpieces of different lengths. The carriage located between the headstock and tailstock carries the cutting tools. An engine lathe differ from a speed lathe in that it has additional features for controlling the spindle speed and for supporting and controlling the feed of the fixed cutting tool which can be in both cross and longitudinal directions with regard to axis of the workpiece.  Workpiece speed may be changed with the help of cone pulleys or through gear shifting. An engine lathe is one of the most widely used lathe.

        (d) Tool Room Lathe- A tool room lathe is a precision engine lathe.  equipped with additional attachments needed for tool and die making operation. A tool room lathe has considerable range in spindle speeds from very low to as high as 2500 r.p.m. A tool room lathe is equipped with steady rest quick change gears, lead screw, feed rod, taper attachment, thread dial, chuck, draw-in-collet attachment and a pump for a coolant. A tool room lathe is tested for accuracy and is used for making highly accurate, low production work.

(2). Medium production lathe-

         (a) Turret and Capstan Lathe - These lathes are medium pro duction, semi-automatic lathes, used to make parts in greater quantities. A very little operator skill is required to operate these machines.  The only skill required is for the setting of tools in the turret or capstan head.  Once the tools are properly setted further operation of these lathes is automatic. These lathes employ special mechanisms for indexing of their tool heads.

                ◆ Ram type turret lathe

                ◆ Saddle type turret lathe

(3). High production lathes-

       (a) Automatic lathe

(4). Special purpose lathe-

        The special purpose lathes are used to manufacture those jobs which cannot be conveniently produced on normally available lathes. Special purpose lathes carry out certain specified operations only but more efficiently than standard lathe.  

        (a) Gap Lathe - In a gap lathe, a section of the bed adjacent to the head stock is recoverable. It is used for machining extra large diameter pieces.

        (b) Duplicating Lathe - A duplicating lathe is used for mass production of identical parts where either a previously machined part works as a template ora separate template is prepared and used. It employs a special tracer attachement, which moves along the template and guides the carriage. 

        (c) Crankshaft Lathe - A crankshaft lathe is used for machining very long parts like turbine and engine shafts and crankshafts.

        (d) Wheel Lathe - Awheel lathe is specially used for finishing the journals and turning the tread on railroad cars and locomotive wheels. 

        (e) Flow Turning Lathe - A flow turning lathe is used for roll flowing, in cold flowing of metals. The lathe may be used for flat plates, forgings and castings, and for extruded and other shapes.