ppt of machine learning and materials slide ppt showing mechanical machine
- 1. INTRODUCTION Non conventional machining (NCM) process is completely non-mechanical. In this process, there is no chip formation. Melting and evaporation of unwanted metal or removal of the metal in the form of powder due to brittle fracture of the metallic layers performs machining operation. These processes are used for machining of difficult profile and for very hard materials.
- 3. MECHANICAL MACHINING • Ultrasonic Machining (USM) and Waterjet Machining (WJM) are typical examples of single action, mechanical non traditional machining processes. • The machining medium is solid grains suspended in an abrasive slurry in the former, while a fluid is employed in the WJM process. • The introduction of abrasives to the fluid jet enhances the machining efficiency and is known as abrasive water jet machining. Similar case happens when ice particles are introduced as in Ice Jet Machining.
- 4. THERMAL MACHINING ➢ Thermal machining removes materials by melting or vaporizing the work piece material. ➢ Many secondary phenomena occur during machining such as microcracking, formation of heat affected zones, striations etc. ➢ The source of heat could be plasma as during EDM and PBM or photons as during LBM, electrons in EBM, ions in IBM etc.
- 5. CHEMICAL AND ELECTROCHEMICAL MACHINING • Chemical milling and photochemical machining or photochemicalblanking all use a chemical dissolution action to remove the machining allowance through ions in an etchant. • Electrochemical machining uses the electrochemical dissolution phase to remove the machining allowance using ion transfer in an electrolytic cell.
- 6. WIRE CUT ELECTRIC DISCHARGE MACHINING
- 7. Working Principle • Figure shows the working principle of wire cut electrical discharge machining. In this type of machining the wire is used as the formof tool electrode. • It is very thin wire of diameter 0.05mmto 0.25mm.The wire is connected to the negative terminal and workpiece is connected to the positive terminal of the DC power supply same as the working of electro discharge machining. The dielectricis calculated to the storage of tank at high pressure pump. The spark can be generateddue to current flowing froma wire and the process is done.
- 8. Advantages of WEDM 1.It gives high accuracy. 2.There is no need of storage of tool is required. 3.There is low operating skill is required. 4.Smooth complex surfaces can be possible to machining. 5.A good surface finish can be obtained. Applications of WEDM 1.It works for production of prototypes. 2.It is used for making of stamping dies, drawings, extrusion tools, etc. 3.IT is used for making blanking dies, plastic molding dies, stamping dies, etc. 4.It is used for gauges, cam discs. 5.It is used to machining larger parts that need to hold accurate tolerances. 6.It is also used for making of small series of spare parts.
- 10. ELECTRICAL DISCHARGEMACHINING ✓ It is also known as Spark over-initiated discharge machining, Spark erosion machining or simply Spark machining. ✓ It is probably the most versatile of all the electrical machining methods. Mechanics of material removal - melting and evaporation aided by cavitations. ✓ This process may be used for machining any material, irrespective of its hardness, which is an electrical conductor.
- 11. ELECTRICAL DISCHARGEMACHINING ✓ The rate of metal removal and the resulting surface finish can be controlled by proper variation in the energy and the duration of spark discharge. ✓ A liquid dielectric, like paraffin or some light oil, like transformer oil or kerosene oil, is always used in the process.
- 12. ELECTRICAL DISCHARGEMACHINING (EDM) Figure 1: Schematic Diagram of EDM
- 13. EDM(CONTD.) Figure 2: Schematic Diagram of EDM
- 15. ELECTRONBEAMMACHINING (PRINCIPLE) ➢ Electron Beam Machining (EBM) is a thermal process. Here a steam of high speed electrons impinges on the work surface so that the kinetic energy of electrons is transferred to work producing intense heating. ➢ Depending upon the intensity of heating the workpiece can melt and vaporize. ➢ The process of heating by electron beam is used for annealing, welding or metal removal.
- 16. ELECTRONBEAMMACHINING ➢ It is a process of machining materials with the use of a high velocity beam of electrons. ➢ The workpiece is held in a vacuum chamber and the electron beam focused on to it magnetically. ➢ As the electrons strike the workpiece, their kinetic energy is converted into heat. ➢ This concentrated heat raises the temperature of workpiece materials and vaporizes a small amount of it, resulting in removal of metal from the workpiece. ➢ The reason for using a vacuum chamber is that, if otherwise, the beam electrons will collide with gas molecules and willscatter.
- 19. LASERBEAMMACHINING (PRINCIPLE) 84 ➢ Laser beam machining (LBM) uses the light energy from a laser device for the material removal by vaporization. ➢ Laser is the term used for the phenomenon of 'amplification of light’ by stimulated emission of radiation’. ➢ A laser is an optical transducer that converts electrical energy into a highly coherent light beam. ➢ The energy of the coherent light beam is concentrated not only optically but also with time.
- 20. LASERBEAM MACHINING 85 ➢The setup consists of a stimulating light source (like flash lamp) and a laser rod. ➢ The light radiated from the flash lamp is focused on to the laser rod (Laser tube), from where it is reflected and accelerated in the path. ➢ This light is emitted in the form of a slightly divergent beam. A lens is incorporated suitably in the path of this beam of light which converges and focuses the light beam on to the workpiece to be machined. ➢This concentration of the laser beam on the workpiece melts the work material and vaporizes it. ➢ It is very costly method and can be employed only when it is not feasible to machine a workpiece through other methods.
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- 23. ULTRASONIC MACHINING 103 ➢ A high frequency electric current is sent by the ultrasonic oscillator to the ultrasonic transducer. ➢ The function of the transducer is to convert this electrical energy into mechanical vibrations. ➢ The vibrations so generated are of the order of 20 kHz to 30 kHz, although the available amplitude usually varies from 15 – 50 μm . ➢ The transducer is made of a magneto strictive material, which is excited by the following high frequency electric current and this results in the generation of mechanical vibrations. ➢ These vibrations are then transmitted to the cutting fool via the intermediate connecting parts, such as transducer cone or horn, connecting body and tool holder.
- 24. ULTRASONIC MACHINING 104 ➢ Slurry of small abrasive particles is forced against the work by means of a vibrating tool, removing the workpiece material in the form of extremely small chips. ➢ The grains used are of silicon carbide, aluminum oxide, boron carbide or diamond dust. ➢ This processes is suitable only for hard and brittle materials like carbides, glass, ceramics, silicon, precious stones, germanium, titanium, tungsten, tool steels, die steels, ferrite quartz,etc. ➢ The vibrating frequency used for the tool is of the order of over 20,000 oscillations second. ➢ Such a high frequency, which is more than the upper limit of audible frequency for human ear' makes the process inaudible(silent).
- 25. ULTRASONIC MACHINING 105 ➢ This makes the tool vibrate in a longitudinal direction, as, shown. ➢ The intermediate parts together form what is known as the focusing unit and the cutting tool is fastened at its end. ➢ The shape of the cutting tool is the same as that of the cavity to be produced by it. ➢ The slurry, formed by the suspension of abrasive grains in a carrier fluid, is fed into the machining area by means of a circulating pump. ➢ However, in order to keep its temperature low a suitable cooling system may be incorporated.
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- 31. WHATIS PLASMA? 121 ➢ When gases are heated to temperatures above 5500°C, they are ionized and exist in the form of a mixture of free electrons, positively charged ions and neutral atoms. This mixture is termed as plasma. ➢ The temperature of central part of plasma goes as high as between 11000°C to 28000°C, where the gas is completely ionized.
- 32. PLASMAARC MACHINING 124 ➢ In Plasma arc machining or Plasma arc cutting, a high velocity jet of this high temperature ionized gas is directed on to the workpiece surface by means of a well-designed torch. ➢ This jet melts the metal of the workpiece and displaces the molten metal away from its path. The heating of workpiece material is not due to any chemical reaction but on account of the continuous attack of electrons which transfer the heat energy of high temperature ionized gas to the work material. ➢ This process can, therefore, be safely used for machining of any metal, including those which can be subjected to chemical reaction.
- 35. ELECTRO-CHEMICAL MACHINING (ECM) ECM is an extension of electroplating with some modifications, but in a reverse direction. Thus ECM can be describe as a controlled anodic dissolution at atomic level of the work piece that is electrically conductive by a shaped tool due to flow of high current at relatively low potential difference through an electrolyte which is quite often water based neutral salt solution.
- 37. ELECTRO-CHEMICAL MACHINING (ECM) Figure: Schematic basic Principle of Electro chemical Machining (ECM)
- 39. PRINCIPLE OF ABRASIVEJET MACHINING • Principle of AJM : In abrasive jet machining process a high speed stream of abrasive particles is mixed with high pressure air or gas are injected through a nozzle on the workpiece to be machined.
- 41. • It consists of a mixing chamber, nozzle, pressure gauge, hopper,filter, compressor, vibrating device, regulator • The gases used in this process are Nitrogen, carbon dioxide Or compressed air • The abrasive particles used in this process are aluminum oxide, silicon carbide, glass powder, dolomite and specially prepared sodium bicarbonate. • Aluminium oxide is a general purpose abrasive and it is used in the sizes of 10,20,25 micron. • Silicon carbide is used for fast cutting on extremely hard materials. The size used to 20,25 microns. • Dolomite of 200 grit size is suitable for light cleaning and etching. • Glass powder of diameter 0.30 to 0.60mm are used for light polishing and deburring.
- 42. • As the nozzle is subjected to a great degree of abrasion wear it is made up of hard materials such as tungsten carbide, synthetic sapphire etc to reduce the wear rate. • Nozzles made of tungsten carbide have an average life of 12 to 20 hours. Synthetic sapphire nozzle have an average life of 300 hours. • Nozzle tip clearance from work is kept at a distance of 0.25 to 0.75mm. • The abrasive powder feed rate is controlled by the amplitude of the vibration of the mixing chamber. A pressure regulator controls the gas or airflow and pressure. • To control the size and shape of cut, either the workpiece is moved or the nozzle is moved by a well designed cam mechanism
- 43. WORKING OF AJM • Dry air or gas enters the compressor through the filter where the pressure of the gas is increased • The pressure of the gas is from 2Kg/cm2 to 8 Kg/cm2 • Compressed air or high pressure gas is supplied to the mixing chamber through the pipe line. The pipe line carries a regulator to control the air or gas flow and its pressure. • The fine abrasive particles are fed through the hopper and fed into the mixing chamber. A regulator is provided to control the flow of abrasive particles. • The mixture of abrasive particles and gas flows through the nozzle at a considerable speed. The mixture flows at a speed of 300m/s. • A vibrator is fixed at the bottom of the mixing chamber. When it vibrates the amplitude of the vibrations controls the flow of abrasive particles.
- 44. WORKING OF AJM • Used for machining hard, brittle and non metallic materials of thin sections. • Examples : Germanium, glass, ceramics and mica. • This process is capable of drilling, cutting, deburring, etching and cleaning the surfaces. • AJM differs from sand blasting process. In AJM metal removal with the use of small abrasive particles is done where in sand blasting only surface cleaning is done.
- 45. ADVANTAGES OFAJM • Process is suitable for cutting all materials. Even diamond can be machined using diamond as an abrasive. • There is no heat generation during this process. Thermal damageof the work piece is avoided. • Very thin and brittle materials can be cut without any risk of breaking. • There is no contact between the workpiece and thetool • Low initial investment • Good surface finish • It can holes shapes be used to cut intricate in hard andbrittle materials
- 46. DISADVANTAGES OFAJM • Material removal rate is slow • Soft material cannot be machined • Machining accuracy is poor. • Nozzle wear rate is high • The abrasive powder used in this process cannot be reused because of decreasing cutting capacity and clogging of the nozzle due to contamination. • There is always a danger of abrasive particles getting embedded in the workpiece. So cleaning is essential after the operation. • It requires some kind of dust collection system.
- 47. APPLICATIONS OF AJM • Machining of hard and brittle materials like quartz,ceramics, glass, sapphire • Fine drilling • Machining of semi conductors • Machining of intricate profiles on hard andbrittle materials • Cleaning and polishing of plastics, nylon and components. • Surface etching and surface preparation • Frosting of the interior surface of the glass tubes.