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Plasma arc welding

Plasma arc welding. A concentrated plasma arc is produced and directed toward the weld area. Higher quality and speed than the TIG. Plasma AW. http://www.youtube.com/watch?v=jo376zPns8I. Plasma cutting. Plasma: gas -(heat)> plasma ( +ions + -electrons )

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Plasma arc welding

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  1. Plasma arc welding • A concentrated plasma arc is produced and directed toward the weld area. • Higher quality and speed than the TIG. Plasma AW http://www.youtube.com/watch?v=jo376zPns8I

  2. Plasma cutting • Plasma: gas -(heat)> plasma ( +ions + -electrons ) • Focused stream of plasma cut sheet metal. • Cutting speed ≈ efficiency, power / thickness, specific heat, melting point : v ≈ ηP / (t w c Tm) Negative electrode - Cutting gas Shielding gas Plasma channel Positive metal + http://www.youtube.com/watch?v=mJJydOxHwZU&feature=results_main&playnext=1&list=PL8EE6E5350B31D89B

  3. Electron-beam Welding • Kinetic energy of high-velocity electrons is converted into heat to strike the workpiece. • The higher the vacuum the more the beam will be able to penetrate the part and the greater depth-to-width ratio. http://www.youtube.com/watch?v=NONurFigP5I

  4. Laser-beam welding • Uses a high-power laser beam as a heat source to produce a fusion weld. • Has a high energy density and a deep penetrating capability. http://www.youtube.com/watch?v=51d6gQxg1KI

  5. Laser-beam Cutting • High power (kW) laser melts and evaporates material. • CO2 & Nd:YAG lasers are used for industrial cutting. Mirror Nd:YAG crystal Xenon Flashlamp Mirror Laser http://ma.gnu.ac.kr/vod/Machining/Laser_beam_machining.MP4

  6. Laser WeldingMachine • Multi axis machine used for laser cutting, welding, marking. http://ma.gnu.ac.kr/vod/Joining/Laser_Welding.wmv Machine

  7. Laser-beam Cutting • Standard roughness ∝ material thickness / laser power, cutting speed : r ∝ t0.5/ (P0.5 v0.3) • Cutting rate ≈ laser power / evaporation energy per volume, thickness, width of laser: v ≈ P / (e t w) Laser beam Focusing lens Gas Material t w

  8. Laser drill Non-contact, a wide range of materials, accuracy and consistency, as small as 10 – 20 microns. Aerospace part: http://www.youtube.com/watch?v=83OQTZZ4ML8 Glass: http://www.youtube.com/watch?v=CS60VzAkhxk

  9. Resistance Welding(전기저항용접) Welding is produced by means of electrical resistance between 2 joined members. Heat generated is H = heat generated (J) I = current (A) R = resistance in ohms t = time (s)

  10. Resistance Welding • Contact resistance of electrode-workpiece < Faying surface resistance of workpiece surface • Pressure reduces contact resistance and is increased after solidification for forging • Rapid, small heat affected zone, no filler, high reliability, automation possible • Mostly lap joint, thickness is limited<12mm, clean interface is needed • Difficult to weld high conductivity material (Al, Cu)

  11. Resistance spot welding Tips of the 2 opposing electrodes contact surfaces of lap joint and resistance heating produces a spot weld. Good bond in the weld nugget isobtained by having pressure continually applied till current is turned off. Strength of weld depends on surface roughness and cleanliness of mating surfaces. http://www.youtube.com/watch?v=AwL1CAg43PU&p=9B6D9EAE75875D9D http://ma.gnu.ac.kr/vod/Joining/Resistance_spot_welding_aluminume.MP4

  12. Resistance Welding Resistance Seam Welding Current and pressure is continuous or on-off through rolls Resistance Projection Welding Many welds simultaneously Plates Electrode Rolls

  13. High frequency welding (고주파용접) • High frequency current up to 450 kHz  Localize heat  Forge the joint • Used for pipe and structural beam welding • Small heat affected zone • Highly conductive material can be easily joined (up to 20 mm)

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