ME 6004 unconventional machining process unit I introduction

ME 6004 unconventional machining processunit IintroductionIntroduction of Unconventional Manufacturing ProcessIn the early stage of mankind, tools were made of stone for the item being made. When iron tools were invented, desirable metals and more sophisticated articles could be produced.In twentieth century products were made from the most durable and consequently, the most unmachinable materials. In an effort to meet the manufacturing challenges created by these materials, tools have now evolved to include materials such as alloy steel, carbide, diamond and ceramics.KINGSTONKINGSTONIntroduction of Unconventional Manufacturing Process

In the figure Merchant had displayed the gradual increase in strength of material with year wise development of material in aerospace industry.In conventional machining processes the ability of the cutting tool is utilized to stress the material beyond the yield point to start the material removal process. This requires that the cutting tool material be harder than the work piece material.The conventional manufacturing processes in use today for material removal primarily rely on electric motors and hard tool materials to perform tasks such as sawing, drilling and broaching.KINGSTONIntroduction of Unconventional Manufacturing Process Conventional forming operations are performed with the energy from electric motors, hydraulics and gravity. Likewise, material joining is conventionally accomplished with thermal energy sources such as burning gases and electric arcs.

Introduction of Unconventional Manufacturing ProcessKINGSTONIn contrast, non-traditional manufacturing processes harness energy sources considered unconventional by yesterdays standards. Material removal can now be accomplished with electrochemical reaction, high temperature plasmas and high-velocity jets of liquids and abrasives.Materials that in the past have been extremely difficult to form, are now formed with magnetic fields, explosives and the shock waves from powerful electric sparks.KINGSTONIntroduction of Unconventional Manufacturing ProcessMaterial-joining capabilities have been expanded with the use of high-frequency sound waves and beams of electrons and coherent light.NEED OF UCM:The advent of harder materials for aerospace applications have made the removal process by conventional methods very difficult as well as time consuming since the material removal rate reduces with an increase in hardness of the work material.Hence machining processes which utilise other methods such as electro-chemical processes are termed as Unconventional or Non-traditional machining methods.Introduction of Unconventional Manufacturing ProcessKINGSTONThe main reasons for using non-traditional processes are : High strength alloys. Complex surfaces. High accuracies and surface finish.

Introduction of Unconventional Manufacturing ProcessKINGSTONCLASSIFICATION OF UNCONVENTIONAL MANUFACTURING PROCESSESThe non-conventional manufacturing processes are not affected by hardness, toughness or brittleness of material and can produce any intricate shape on any work piece material by suitable control over the various physical parameters of the processes.Thus, these non-conventional processes can be classified into various groups according to the basic requirements which are as follows :KINGSTONIntroduction of Unconventional Manufacturing ProcessType of energy :Chemical Electro-chemical Mechanical Electrical andThermal.Mechanism of metal removal :Shear Erosion Chemical ablation Ionic dissolution Spark erosion VaporisationKINGSTONIntroduction of Unconventional Manufacturing ProcessMedia for energy transfer :Physical contact High velocity particles Reactive atmosphere Electrolyte Hot gases Electrons RadiationSource of energy :Hydraulic or pneumatic pressure Mechanical pressure Corrosive agent High current High voltage Ionized gasKINGSTONIntroduction of Unconventional Manufacturing ProcessCommon Unconventional Machining Methods :Electrical Discharge Machining (EDM) Electro-Chemical Machining (ECM) Electro-Chemical Grinding (ECG) Ultrasonic Machining (USM) Electron Beam Machining (EBM) Laser Beam Machining (LBM) Plasma Arc Machining (PAM) Abrasive Jet Machining (AJM) Chemical Machining (CHM). KINGSTONIntroduction of Unconventional Manufacturing ProcessKINGSTON

COMPARATIVE ANALYSIS OF UNCONVENTIONAL MANUFACTURING PROCESSESA particular manufacturing process found suitable under the given conditions may not be equally efficient under other conditions. Therefore, a careful selection of the process for a given manufacturing problem is essential. The analysis has been made from the point of view of :Physical parameters involved in the processes;Capability of machining different shapes of work material;Applicability of different processes to various types of material, e.g. metals, alloys and non-metals;Operational characteristics of manufacturing and Economics involved in the various processes.Introduction of Unconventional Manufacturing ProcessKINGSTONPhysical parametersThe physical parameters of non-conventional machining processes have a direct impact on the metal removal as well as on the energy consumed in different processes.Introduction of Unconventional Manufacturing Process

KINGSTONFrom a comparative study of the effect of metal removal rate on the power consumed by various non-conventional machining processes shown in fig.Introduction of Unconventional Manufacturing ProcessKINGSTON

It is found that some of the processes (e.g. EBM, ECM) above the mean power consumption line consume a greater amount of power than the processes (e.g. EDM, PAM, ECG) below the mean power consumption line. Thus, the capital cost involved in the processes (EBM, ECM etc.) lying above the mean line is high whereas for the processes below that line (e.g., EDM, PAM, MCG) is comparatively low.Introduction of Unconventional Manufacturing ProcessKINGSTONCapability to shapeThe capability of different processes can be analysed on the basis of various machining operation point of view such as micro-drilling, drilling, cavity sinking, pocketing (shallow and deep), contouring a surface, through cutting (shallow and deep) etc.Introduction of Unconventional Manufacturing ProcessKINGSTON

For micro-drilling operation, the only process which has good capability to micro- drill is laser beam machining while for drilling shapes having slenderness ratio , the process USM, ECM and EDM will be most suitable.EDM and ECM processes have good capability to make pocketing operation (shallow or deep).For surface contouring operation, ECM process is most suitable but other processes except EDM have no application for contouring operation.Introduction of Unconventional Manufacturing Process

KINGSTONApplicability to materials

KINGSTONIntroduction of Unconventional Manufacturing Process

Machining characteristicsThe machining characteristics of different non-conventional processes can be analysed with respect to :Metal removal rate Tolerance maintainedSurface finish obtained Depth of surface damagePower required for machining

KINGSTONEconomics of the processesCapital cost Tooling costConsumed power costMetal removal rate efficiencyTool wear.KINGSTON