VEER SURENDRA SAI UNIVERSITY OF TECHNOLOGY BURLA, ODISHA, DEPARTMENT OF PRODUCTION ENGINEERING Lecture Notes on NON-TRADITIONAL MACHINING (NTM) COURSE CODE: BMS 401 7th Semester B. Tech in Production Engineering
MOUDULE- I Introduction: Need for Non-Traditional Machining, Classification, Process Selection Ultrasonic Machining: Principle, Transducer, Magnetrostrictive material, Analysis for material removal rate by Shaw, Effect of process parameters, Application.
1.1 INTRODUCTION The industries always face problems in manufacturing of components because of several reasons. This may be because of the complexity of the job profile or may be due to surface requirements with higher accuracy and surface finish or due to the strength of the materials. In 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 un-Machinable 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. A similar evolution has taken place with the methods used to power our tools. Initially, tools were powered by muscles; either human or animal. However as the powers of water, wind, steam and electricity were harnessed, mankind was able to further extend manufacturing capabilities with new machines, greater accuracy and faster machining rates. HSTR Alloys 14000 Titanium 7000 Al alloy 3500 1400 700 Al 350 1915 1930 1945 1960 Year of development Trend of increase of material strength 1
Every time new tools, tool materials, and power sources are utilized, the efficiency and capabilities of manufacturers are greatly enhanced. Since 1940’s, a revolution in manufacturing has been taking place that once again allows manufactuers to meet the demands imposed by increasingly sophisticated designs and durable but in many cases nearly unmachinable, materials. In the Above figure Merchant had displayed the gradual increase in strength of material with year wise development of material in aerospace industry. This manufacturing revolution is now, as it has been in the past, centered on the use of new tools and new forms of energy. The result has been the introduction of new manufacturing processes used for material removal, forming and joining, known today as non-traditional manufacturing processes. Non-traditional manufacturing processes harness energy sources considered unconventional by yesterday’s 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. Material-joining capabilities have been expanded with the use of high-frequency sound waves and beams of electrons and coherent light. During the last 55 years, over 20 different non-traditional manufacturing processes have been invented and successfully implemented into production. 1.2 CLASSIFICATION OF UNCONVENTIONAL MANUFACTURING PROCESSES The non-conventional manufacturing processes are not affected by hardness, toughness or brittleness of material and can produce any intricate shape on any workpiece material by suitable control over the various physical parameters of the processes. The non-conventional manufacturing processes may be classified on the basis of type of energy namely, mechanical, electrical, chemical, thermal or magnetic, apply to the workpiece directly and have the desired shape transformation or material removal from the work surface by using different scientific mechanism. Thus, these non-conventional processes can be classified into various groups according to the basic requirements which are as follows : (i) Type of energy required, namely, mechanical, electrical, chemical etc. (ii) Basic mechanism involved in the processes, like erosion, ionic dissolution, vaporisation etc. (iii) Source of immediate energy required for material removal, namely, hydrostatic pressure, high current density, high voltage, ionised material, etc. (iv) Medium for transfer of those energies, like high velocity particles, electrolyte, electron, hot gases, etc. On the basis of above requirements, the various processes may be classified as shown