MMM LECTURE NOTES FINAL.pdf

Perforation of sheets for perforation by ebm to be

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Perforation of Sheets: For perforation by EBM to be economically acceptable, 104 to 105 holes per second have to be produced.Thus single pulses lasting only a few microseconds are needed. In some applications the sheet or foil is stretched on a rotating drum, which is simultaneously shifted in the direction of its axis. Rows of perforations following a helical line are thereby produced. Manipulators capable of linear and rotating movements in four axes are used for EBM perforation of jet engine components. Foil made of a synthetic material has been perforated with 620 holes per square millimeter for filter application at a rate of one hole every 10 μs. EBM perforation can be applied to the production of filters and masks of colour television tubes. Other applications for perforation lie in sieve manufacture, for sound insulation and in glass fiber production.
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Modern Manufacturing Methods Slotting: Rectangular slots of 0.2 by 6.35 mm in 1.57-mm-thick stainless steel plate are produced in 5 min using 140 kV, 120 μA, a pulse width of 80 μs, and a frequency of 50 Hz. The rate of slotting depends on the work piece thickness. In this regard 0.05-mm-thick stainless steel was cut at a rate of 100 m/min, while 0.18-mm-thick stainless steel was cut at 50 m/min using similar machining conditions . Advantages a. Drilling is possible at high rates (up to 4000 holes per second). b. No difficulty is encountered with acute angles. c. Drilling parameters can easily be changed during machining. d. No limitation is imposed by work piece hardness, ductility, and surface Reflectivity. e. No mechanical distortion occurs to the work piece since there is no contact. f. The process is capable of achieving high accuracy and repeatability of 0.1 mm for position of holes and 5 percent for the hole diameter. g. The process produces the best surface finish compared to other Processes. h. The cost is relatively small compared to other processes used to produce Very small holes. Disadvantages a. High capital equipment cost b. Long production time due to the time needed to generate a vacuum c. The presence of a thin recast layer d. Need for auxiliary backing material Laser Beam Machining Introduction Laser-beam machining is a thermal material-removal process that utilizes a high-energy,coherent light beam to melt and vaporize particles on the surface of metallic and non-metallicworkpieces. Lasers can be used to cut, drill, weld
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Modern Manufacturing Methods and mark. LBM is particularly suitable for making accurately placed holes. A schematic of laser beam machining is shown in Figure. Different types of lasers are available for manufacturing operations which are as follows: · CO2 (pulsed or continuous wave): It is a gas laser that emits light in the infrared region. It can provide up to 25 kW in continuous-wave mode.
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  • Fall '12
  • JeraldBrevick
  • EDM, conventional machining processes, Jet Machining

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