Nontraditional Manufacturing Processes Alessandro Anzalone, Ph.D. Hillsborough Community College, Brandon Campus Agenda 1. Introduction 2. Electrodischarge Machining 3. Electrochemical Machining (ECM) and Electrochemical Deburring (ECDB) 4. Electrolytic Grinding (ELG) 5. Lasers and Laser Machining 6. Ultrasonic Machining 7. Water Jet Machining and Abrasive Water Jet Machining 8. Electron Beam Machining 9. Plasma Technology 10. References 1
Introduction The design and manufacturing engineer, in the continuing search for design improvements, stimulates development of alternative materials processing methods and takes advantage of new technologies as they evolve. Machining i processes have developed d in recent years that make use of electricity, laser light, electrochemical methods, and extremely high temperature gas plasma. These processes, because of their unique capabilities, have opened many new avenues of design to the engineer. The processes described in this chapter are often referred to as nontraditional machining processes because they do not involve the chip-making process of conventional machining. They are nonetheless well established as standard manufacturing processes. Electrodischarge Machining Electrodischarge machining, commonly known as EDM, removes workpiece material by an electrical spark erosion process. This process is accomplished by establishing a large potential (voltage) difference between the workpiece to be machined and an electrode. A large burst (spark) of electrons travels from the electrode to the workpiece. When the electrons impinge on the workpiece some of the workpiece material is eroded away. http://www.youtube.com/watch?v=q4finksdfww 2
Electrodischarge Machining http://www.productool.com http://www.iqsdirectory.com Electrodischarge Machining Advantages and Applications of EDM EDM processes can accomplish machining that would be impossible by traditional methods. Odd electrode shapes are reproduced d in the workpiece, and fine details can be created, such as those needed in tool, die, and mold work. When EDM is coupled to numerical control, an excellent machining system is made available to the tool and die maker. Because electrodischarge machining is accomplished by spark erosion, the electrode does not touch the workpiece and is therefore not dulled by hard workpiece materials that would dull conventional cutters. The EDM process is commonly used to spark erode very hard metals, and this process has found wide application in removing broken taps without damaging the workpiece. 3
Electrodischarge Machining Disadvantages of EDM The EDM process is much slower, from a metal removal standpoint, than conventional machining i processes involving i direct cutter contact. There is also a possibility of softening the workpiece surface in the area of the cut in the parts being machined; however, EDM can accomplish many machining tasks that could not be done by conventional machining. Thus, the EDM process has become well established as a versatile manufacturing process in modem industrial applications. Electrochemical Machining (ECM) and Electrochemical Deburring (ECDB) Electrochemical machining (ECM) is essentially a reverse metalplating process. The process takes place in a conducting fluid (electrolyte) that is pumped under pressure between the electrode and the workpiece. As workpiece material is deplated d it is flushed away by the flow of electrolyte, and the workpiece material is removed from the electrolyte by a filtration system. The ECM electrode does not wear, and sufficient flow of the electrolyte prevents workpiece material from plating onto the electrode. http://www.youtube.com/watch?v=jhexo_rptpa 4
Electrochemical Machining (ECM) and Electrochemical Deburring (ECDB) Advantages and Applications of ECM Like EDM, ECM can accomplish machining of intricate shapes in hard-to-machine hi material. The process is also burr free and does not subject the workpiece to distortion and stress, as do conventional machining processes. This makes ECM useful for work on thin or fragile workpieces. ECM is also used for part deburring in the process called electrochemical deburring. This process is useful for deburring internal workpiece features that are inaccessible to traditional mechanical deburring. Electrolytic Grinding (ELG) In the process of electrolytic grinding (ELG) an abrasive wheel much like a standard grinding wheel is used. ELG, like ECM, is a deplating process, and workpiece material is carried away by the circulating electrolyte. l t Also, like ECM, ELG is effective in removing material from very hard workpieces. As the ELG process deplates a portion of the workpiece material it also transforms the surface layer of material into an oxide layer that is more readily removed by the abrasive wheel. The abrasive wheel bond is metal, thus making it a conductor of electricity. The abrasive grains in the grinding wheel are nonconducting and help maintain the gap between wheel and work while removing the oxide layer from the workpiece. http://www.youtube.com/watch?v=76ptnnvn0ou http://www.saitama-bsc.jp/english/top_technology/shinsedai/index.html 5
Electrolytic Grinding (ELG) Advantages and Applications Because this process is electrochemical and mechanical, unlike conventional grinding, the abrasive wheel in ELG wears little in the process. ELG is burr free and will not distort or overheat the workpiece. The process is therefore very useful for small precision parts and thin or fragile workpieces, and the ECG process can remove material from very hard, conducting workpieces at a higher material removal rate than can conventional abrasive machining processes. Lasers and Laser Machining Laser is an acronym for light amplification by stimulated emission of radiation. By electrically stimulating the atoms of certain materials, such as various crystals and certain gases, the electrons of these atoms can be temporarily displaced d to higher h electron shell energy level positions within the atomic structure. When the electrons fall back to their originally stable levels photons of light energy are released. This light energy can be enhanced and focused into a coherent beam and then used in manufacturing, medical, measurement, and other useful applications. The applications of lasers in manufacturing are widespread, and laser energy finds many applications other than use as a cutting tool. http://www.explainthatstuff.com/laser.png 6
Lasers and Laser Machining Laser Machining In laser machining, the coherent laser light becomes the cutting tool. Integrating ti the laser with CNC machine tool positioning i provides extremely versatile systems with many capabilities. Applications of laser machining tools include cutting plates, cutting shapes from thin materials, slotting stainless tubing, marking, and engraving. http://www.youtube.com/watch?v=1gub5ptkaxu&feature=related http://www.youtube.com/watch?v=emdqbwaf5lw Ultrasonic Machining Ultrasonic machining is an abrasive process similar to sand blasting. High-frequency vibration is used as the motive force that propels abrasive particles against the workpiece. Advantages of this process include the ability to machine very hard material with little distortion. Good surface finishes may be obtained, and part features of many different shapes can be machined. http://www.youtube.com/watch?v=mnnkds87sw8 7
Water Jet Machining and Abrasive Water Jet Machining The cutting tool in the water jet machining process is an extremely high pressure water jet. Pressures of several thousand pounds per square inch are used to pump water through a small nozzle that directs a narrow stream at the workpiece. This process is effective in cutting fabric, foam rubber, and similar low-strength materials. In abrasive water jet machining (AWJ), the efficiency of the process is enhanced by adding an abrasive material to the water. Both pressure and mechanical abrasion join forces to accomplish cutting and machining tasks. The process may be used for hard metallic materials, but there are limitations on the thickness of the materials being machined. http://www.youtube.com/watch?v=hpimtm8k4wa http://www.youtube.com/watch?v=crgujrcyhhe&feature=related Electron Beam Machining Electron beam machining (EBM) is related to EDM and to electron beam welding. In EDM, however, a burst of electrons (spark) impinges on the workpiece, whereas electrons in a continuous beam are used in the EBM process. In EBM the workpiece material is heated and vaporized by the intense electron beam. This process, like electron beam welding, must occur in a vacuum chamber, and appropriate shielding must be employed to protect personnel from X-ray radiation. http://www.youtube.com/watch?v=fdyusleapiq 8
Plasma Technology Plasma cutting is an extremely fast process for cutting, welding, and machining nonferrous metals and stainless steel. Plasma is created by passing a gas through an electric arc. The gas is ionized by the arc, and an extremely high h temperature t results. Temperatures in plasma arcs can exceed 40,000 F, many times hotter than any arc or flame temperature produced by other processes. When the superheated gas is forced through a venturi, a high-velocity jet is created that instantly melts metals on contact and blows the molten material away from the cut. Plasma arcs of such high temperatures have a multitude of uses, not only in machining but for other applications such as ore smelting and waste metal recovery operations. There is also ongoing research in the applications of high- temperature plasmas for incinerating industrial wastes. Plasma Technology http://www.bb.ustc.edu.cn/ocw/nr/rdonlyres/global/7/77e722fa-4a00-476d-9d4a-3f86c9bda2b3/0/chp_sun_plasma.jpg http://www.youtube.com/watch?v=mjjydoxhwzu http://www.youtube.com/watch?v=0bajpq-cytm&feature=fvw 9
References 1. R Gregg Bruce, William K. Dalton, John E Neely, and Richard R Kibbe,, Modern Materials and Manufacturing Processes, Prentice Hall, 3rd edition, 2003, ISBN: 9780130946980 10