Modern manufacturing methods

MMM

1. MODERN MANUFACTURING METHODS UNIT-I INTRODUCTION Prepared by S.M. Girish Kumar

2. Characteristics of Modern Manufacturing Methods / NTM Material removal may occur with chip formation or even no chip formation may take place. For example, in AJM, chips are of microscopic size and in case of Electrochemical machining material removal occurs due to electrochemical dissolution at atomic level. In NTM, there may not be a physical tool present. For example, in laser jet machining, machining is carried out by laser beam. However, in Electrochemical Machining there is a physical tool that is very much required for machining In NTM, the tool need not be harder than the work piece material. For example, in EDM, copper is used as the tool material to machine hardened steels. Mostly NTM processes do not necessarily use mechanical energy to provide material removal. They use different energy domains to provide machining. For example, in USM, AJM, WJM mechanical energy is used to machine material, whereas in ECM electrochemical dissolution constitutes material removal Continued………..

3. Characteristics of Modern Manufacturing Methods / NTM In many processes, material removal rate is independent of the hardness of the work piece.  Cutting forces are independent of the hardness of the work material. Generally, tool wear is negligible hence tool wear is not a problem  No burr is left on the work piece Generally, no residual stresses are left on the surfaces machined In most of the cases entire shape can be obtained in one stage or in one setting. This is possible since material removal takes place uniformly over the entire area below the tool simultaneously. Modern machining methods can be integrated easily with micro-processors and numeric controls for better control of the processes and for improving the versatility and productivity of the machines Intricately shaped contours and fine machining of precision holes are possible. Continued………..

4. Advantages of Modern Manufacturing Methods / NTM Complex geometries beyond simple planar or cylindrical features Parts with extreme surface finish and tolerance requirements Delicate components that cannot withstand large cutting forces Parts without producing burrs or inducing residual stresses Brittle materials or materials with very high hardness.

5. Need For Modern Manufacturing Methods / NTM With the development of technology more & more challenging problems are face by the scientist & technologists in the field of manufacturing Technologically advanced industries like aeronautics, nuclear reactors, automobiles etc , have been demanding materials like “high strength temperature resistant (HSRT) alloy having “strength to weight “ratio Extremely hard and brittle materials or Difficult to machine materials are difficult to machine by traditional machining processes. When the work piece is too flexible or slender to support the cutting or grinding forces. When the shape of the part is too complex

6. Need For Modern Manufacturing Methods / NTM 6. Researchers in the area of materials science are developing materials having high strength, hardness, toughness etc. The difficulty in adopting the traditional manufacturing process can be attributed mainly to the following three basic sources New materials with low machinability Dimensional and accuracy requirements A high production rate & economy

7. Basic Principle Of Modern Manufacturing Methods : The basic principle of machining by these new methods is to apply some form of energy to the work piece directly without almost any physical contact between the tool and the work piece and have the desired shape by material removal from the work piece. Different forms of energy applied to the work piece are: Mechanical Energy, Electrical (Electro-chemical energy), Thermal Energy, Chemical Energy.

8. Classification of Modern Manufacturing Methods : Mechanical Energy Electrical Energy (Electro-chemical energy) Thermal Energy (Thermo- electric energy) Chemical Energy

9. Classification of Modern Manufacturing Methods : Mechanical Energy Conventional machining Abrasive Jet Machining (AJM) Water Jet machining (WJM) Ultrasonic machining (USM) 2. Electrical Energy Electro-chemical machining Electro-chemical grinding Electro-chemical Deburring Electro-chemical Honing

10. Classification of Modern Manufacturing Methods : 3 Thermal Energy Spark erosion machining or Electro-discharge machining (EDM) Electron-Beam machining (EBM) Ion-Beam machining Laser-Beam machining Plasma-Arc machining 4. Chemical Energy Chemical machining Electro-polishing Photo-chemical machining

11. Energy type Mechanics of material removal Energy source Process     Mechanical Plastic shear Mechanical motion of tool/job Conventional machining Erosion Mechanical fluid motion Abrasive jet machining (AJM) Ultrasonic machining (USM) ,WJM, AWJM Electrochemical Ion displacement Electric current Electrochemical machining (ECM)   Mechanical & Electro chemical Plastic shear & Ion displacement Electric current & Mechanical motion Electrochemical and mechanical grinding(ECG) Electro Jet Drilling (EJD)     Chemical Corrosive agent Corrosive agent Chemical machining (CHM) Fusion reaction Electric spark Electric discharge machining (EDM)   High speed electrons Electron beam machining (EBM)   Thermal   Powerful radiation Laser beam Machining (LBM) Ionized substance Ion beam machining( lBM )   Plasma arc machining (PAM) ,

12. Machining Characteristics of Modern Manufacturing Methods : The machining characteristics of different non-conventional processes can be analyzed with respect to: Metal removal rate   Tolerance maintained   Surface finish obtained   Depth of surface damage   Power required for machining

13. Econmics of Modern Manufacturing Methods : The economics of the various processes are given below Tooling cost Consumed power cost Metal removal rate efficiency Tool wear.