Theory about LATHE machine tool and operations performed on it. Very useful for diploma students

Detailed discussion on lathe and its accessories, working and cost estimation

1. Department of Collegiate and Technical Education Introduction to Lathe (Week 4) Session-II Course Outcome : CO3 MACHINE TOOL TECHNOLOGY ( IIIrd Semester) Mechanical Engineering Mechanical Engineering – 20ME32P

2. Introduction to Lathe: Types of Lathes Major parts of Centre Lathe Capstan & Turret Lathe Automatic Lathes: - Single Spindle Automats, Multi Spindle Automatics Parallel action multi spindle, Progressive action multi spindle automats Cutting Fluids: - Types of cutting fluids, Selection of cutting fluids Contents

3. Introduction to Lathe Lathe is the oldest machine tool invented, starting with the Egyptian tree lathes. It is the father of all machine tools. Its main function is to remove material from a work piece to produce the required shape and size. This is accomplished by holding the work piece securely and rigidly on the machine and then turning it against the cutting tool which will remove material from the work piece in the form of chips. It is used to machine cylindrical parts. Generally single point cutting tool is used

4. Types of Lathes Speed Lathe: - Wood working, Centering, Polishing, Spinning Engine Lathe: - Belt drive, Individual motor drive, Gear head lathe Bench Lathe Tool room Lathe Capstan & Turret Lathe Special purpose Lathe: - Wheel Lathe, Gap bed Lathe, T-Lathe, Duplicating Lathe Automatic Lathe: - CNC Lathe

5. Constructional Features / Major parts of Centre Lathe

6. Main Parts of Centre Lathe Head Stock Tail Stock Bed Carriage Saddle Cross-slide Compound Rest Tool post Apron Feed Mechanism Feed rod Lead screw

7. Configuration of Capstan Lathe

8. Configuration of Turret Lathe

9. Major Parts of Capstan & Turret Lathe Bed Head Stock: - Step cone pulley, Direct electric motor, All geared, pre- optive /pre-selective head stocks Cross slide: - Conventional type, Side hung type Saddle: - Ram saddle, Turret saddle Turret

10. Automatic Lathes These are machine tools in which the components are machined automatically. The working cycle is fully automatic that is repeated to produce identical parts without participation of the operator. All the working and idle operations are performed in a definite sequence by the control system adopted in the automats which is set up to suit a given work

11. Single spindle Automat

12. Working Principle The stock is held by a rotating collet in the head stock and all longitudinal feeds are obtained by a cam which moves the head stock as a unit. Most diameters turning are done by two horizontal tool slides while the other three slides are used principally for such operations as knurling, chamfering, recessing and cutting off. The tools are controlled and positioned by cams that bring the tools in as needed to turn, face, form, and cut off the work piece from the bar as it emerges from the bushing

13. Parallel action Multi spindle Automat

14. Working Principle These machines are usually automatic cutting off bar type machines. This is also called as ‘multiple-flow’ machine. In this machine, the same operation is performed on each spindle and a work piece is finished in each spindle in one working cycle. The rate of production is very high, but the machine can be employed to machine simple parts only since all the machining processes are done at one position

15. Progressive action Multi spindle Automat

16. Working Principle The spindle carrier indexes on its own axis by 60 (360 /6) at each tool retraction. As the spindle carrier indexes, it carries the work from station to station, where various tools operate on it. The stock moves around the circle in counter clockwise direction and comes to the station number 6 for cutting off. A finished component is obtained for one full revolution of the spindle carrier

17. Cutting Fluids The basic purposes of cutting fluid application are: Cooling of the job and the tool to reduce the detrimental effects of cutting temperature on the job and the tool. Lubrication at the chip - tool interface and the tool flanks to reduce cutting forces and friction and thus the amount of heat generation. Cleaning the machining zone by washing away the chip - particles and debris which, if present, spoils the finished surface and accelerates damage of the cutting edges.

18. Contd., Protection of the nascent finished surface - a thin layer of the cutting fluid sticks to the machined surface and thus prevents its harmful contamination by the gases like SO 2 , O 2 , H 2 S, and N X O Y present in the atmosphere. However , the main aim of application of cutting fluid is to improve machinability through reduction of cutting forces and temperature, improvement by surface integrity and enhancement of tool life

19. Essential properties of cutting fluids Good lubricating quality High heat absorption capacity High flash point stability Emits no fumes while in contact with hot surface Harmless to workers and work piece Non corrosive to work surface and machine High fluidity Low viscosity

20. Contd., It should not be chemically reactive It should be odorless Cheap and easily available It should be transparent

21. Types of cutting fluids 1. Solid Cutting fluids Graphite Molybdenum disulphide Stick waxes Bar soaps Tale in conjunction with fatty oil and sulphur

22. Contd., 2. Liquid Cutting fluids Water Straight oil: - Mineral oils, Straight fatty oils, Mineral lard oils Soluble oils Chemical additive oils Chlorinated oils Sulphurised cutting oils

23. Contd., 3. Gaseous cutting fluids Air (still or compressed) Carbon dioxide Argon

24. Selection of Cutting fluids Depending upon the nature of work the cutting fluids are selected on the following basis. Type of operation The rate of metal removal Material of the work piece Material of the tool Surface finish requirement Cost of cutting fluid

25. REFERENCES Elements of Workshop Technology (Vols. 1 and II) by Hajra Chaudhary . Production Technology By R.K. Jain Foundry Technology By O.P.Khanna Engineering Drawing Vol-2 By K.R.Gopala Krishna Engineering Drawing By N.D.Bhat

26. Thank you Content Developers Shri . Nataraj Kuntoji, GPT Bagalkote / 152 Shri . H.B.Goudar , GPT Bagalkote /152 Shri . Shivakumar Pujeri , GPT Bagalkote /152 Shri . Hanamant.B.Teggi , GPT Bagalkote /152