Arc welding types( carbon,TIG &MIG )

TIG Welding , MIG welding, Carbon arc welding

1. YoucaN Arc welding types YoucaN Compiled by Pravinkumar Kamatchi St.Josephs College of Engineering Assistant Professor

2. Types of arc welding Carbon arc welding Gas metal arc welding(GMAW)(MIG) Gas tungsten arc welding(GTAW)(TIG) Submerged arc welding Electro slag welding etc YoucaN

3. Carbon arc welding OR Twin Carbon Electrode Arc Welding Carbon Arc Welding (CAW) is a welding process, in which heat is generated by an electric arc struck between an carbon electrode and the work piece . The arc heats and melts the work pieces edges, forming a joint . Electrode is non-consumable. Shields (neutral gas, flux) may be used for weld pool protection depending on type of welded metal. YoucaN

4. CARBON ARC WELDING (CAW) Carbon electrode Air Filler Rod Weld Bead Developed in 1884 1. Power source 2. Holder cable 3. Earth cable 4. Work 5. Carbon electrode & 6.Filler rod YoucaN

5. Carbon arc welding YoucaN Used to weld: brass, bronze, copper alloys

6. Carbon arc welding Advantages of Carbon Arc Welding: Low cost of equipment and welding operation; High level of operator skill is not required; The process is easily automated; Low distortion of work piece. Disadvantages of Carbon Arc Welding: Unstable quality of the weld (porosity); Carbon of electrode contaminates weld material with carbides . YoucaN

7. Tungsten Inert Gas welding YoucaN

8. Gas tungsten arc welding(GTAW) It is also known as TIG welding. It uses tungsten as electrode ( added with 1-2% thorium and zircon. It improves electron emission and arc stability ) that is non-consumable (3400 o C ) Electrode holder is used to fix it. Instead of flux An inert gas is supplied from a cylinder passes through the nozzle to protect the welding zone. It surrounds the arc from the atmosphere and make a defect free weld also it protects the tungsten electrode. YoucaN

9. Gas tungsten arc welding(GTAW) Welding head: Light weight handle having tungsten holder. Gas flow – (also cooled the electrode) For high heat – water cooled guns. YoucaN

10. YoucaN With shielding gas With out shielding gas

11. YoucaN ER70S-6 is generally used for mild steel welding. Rod dia 0.8 to 5mm Speed 8mm/s to 50mm/s Water outlet

12. YoucaN ER70S-6 is generally used for mild steel welding. Rod dia 0.8 to 5mm Speed 8mm/s to 50mm/s Water outlet

13. Gas tungsten arc welding(GTAW) YoucaN Rod dia 0.8 to 5mm Speed 8mm/s to 50mm/s ER70S-6 is generally used for mild steel welding.

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15. Chemical composition of ER70S-6 AWS Chemical Composition Requirements C = 0.06 – 0.15 Ni = 0.15 max Mn = 1.40 – 1.85 Cr = 0.15 max Si = 0.80 – 1.15 Mo = 0.15 max P = 0.025 max V = 0.03 max YoucaN ER indicates filler metal may be used as either an electrode or rod . 70 indicates in 1000 psi(pounds per square inch) increments the minimum tensile strength of the weld metal produced by the electrode when tested according to the specification. In this case, 70 indicates 70,000 psi . S indicates that the filler metal wire is solid . 6 indicates the chemical composition of the solid filler metal wire. This wire has a Charpy V Notch impact property of -29 C.

16. Gas tungsten arc welding(GTAW) Filler material may or may not be used. Mostly DCSP (straight polarity ie . electrode to w/p electron flow)is used. Because DCRP melts the tungsten . Used to weld: steel, aluminium , CI, stainless steel, nickel based alloy, copper based alloy and low alloy steels. Used upto thickness 6.5mm . YoucaN

17. Gas tungsten arc welding(GTAW) Applications Welding of sheet metal and thinner sections Precision welding in aircraft, chemical and instrumental industries. YoucaN

18. Gas tungsten arc welding(GTAW) Advantages: No flux Speed welding Used in both ferrous and non-ferrous welding High quality welding No weld cleaning is necessary YoucaN

19. Gas tungsten arc welding(GTAW) Disadvantages: High cost Slow process Separate filler rod is required YoucaN

20. video 4. Gas Tungsten Arc Welding YoucaN

21. Gas Metal Arc Welding or MIG YoucaN

22. MIG YoucaN Is a process where a continuously fed metal electrode (Wire) contacts the base metal and produces heat. The arc is shielded by an inert gas

23. GMAW component diagram YoucaN

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39. GMAW Components DC or Direct Current power supply Electrode or wire feed controller Wire drive roller assembly Shielding gas source (cylinder) & regulator Manually held Gun & ground clamps Wire reel YoucaN

40. Gas Metal Arc Welding In MIG consumable electrode is used. Shielded gas also used (stable gases Ar , He,CO 2 ). The gases must be clean and free form moisture. Automatic wire feed mechanism. Wire Speed is depends on voltage. The GMAW process is performed using DCEP (Direct Current Electrode Positive) Alternating current is never used for GMAW YoucaN

41. Gas Metal Arc Welding Helium(He) Better penetration, minimizing distortion, costly. Argon Good electrical property(low ionization voltage ), cheaper than He, superior oxide cleaning. Due to its softer arc and less penetration it is best for thin metals. Carbon dioxide: Cheaper one. But produces spatter and poor bead shape. YoucaN

42. Several tips must be consider in selecting mode of transfer Type, intensity and polarity of welding current Electrode size Electrode composition Electrode extension Shielding gas mix composition YoucaN

43. Gas Metal Arc Welding- metal transfer technique Dip or short circuit- E lectrode wire dips in weld pool, causing a momentary shot circuit, burns the wire. This takes place at very high speed 100 dips/s. drops of liquid metal get transferred by gravity and surface tension. Globular- D rop by gravity, low current and voltage Spray- H igh current density, very small droplets and more frequent. Pulsed arc welding - A duel power unit, rapid acceleration of droplets due to peak and low current cycles. YoucaN

44. Modes of GMAW Transfer YoucaN

45. Short Circuit (Short Arc) Operates at low voltages and welding current Small fast-freezing weld puddle obtained Useful in joining thin materials in any position, as well as thick materials in vertical and overhead positions Metal transfer occurs when an electrical short circuit is established this cycle can repeat itself between 20 and as much as 250 times per second. YoucaN

46. Short Circuit YoucaN A - Electrode is short circuited to base metal. No arc, and current is flowing through electrode wire and base metal. B - Resistance increases in electrode wire causing it to heat, melt and “neck down”. C - Electrode wire separates from weld puddle , creating an arc. Small portion of electrode wire is deposited which forms a weld puddle. D - Arc length and load voltage are at maximum . Heat of arc is flattening the puddle and increasing the diameter tip of electrode. E - Wire feed speed overcomes heat of arc and wire approaches base metal again. F - Arc is off and the short circuit cycle starts again.

47. Globular Transfer Welding current and wire speed are increased above maximum for short circuit Droplets of metal have a greater diameter than the wire being used Spatter present Welding is most effectively done in the flat position when using globular transfer YoucaN

48. YoucaN Globular transfer is often a high voltage, high amperage, high wire feed speed transfer, and is the result of using CO 2 shielding gas (or 75% AR-25% CO 2 ) with parameters higher than the short-circuiting range.

49. Spray Arc Transfer Occurs when the current and voltage settings are increased higher than that used for Globular Transfer Used on thick sections of base material , best suited for flat position due to large weld puddle. The spray is projected by electromagnetic forces towards the weld pool Spatter is minimal to none Uses 5% to 10% CO 2 mix with argon or oxygen. > Forms very small droplets of metal >Very good stability > Very little spatter YoucaN

50. YoucaN Spray arc transfer “sprays” a stream of tiny molten droplets across the arc, from the electrode wire to the base metal. Spray arc transfer uses relatively high voltage, wire feed speed and amperage values, compared to short circuit transfer.

51. Pulse Spray Transfer GMAW-P was developed for two demanding reasons: control of weld spatter and the elimination of incomplete fusion defects common to globular and short-circuiting transfer. The welding current alternates between a peak current and a lower background current . This faster-freezing weld puddle is what allows the pulsed-spray transfer to be used fort thinner metals, B etter control on out-of-position work. A llows for larger wire sizes to be used on varied metal thicknesses. YoucaN

52. YoucaN In pulse spray transfer (GMAW-P) the welding power source’s pulse control pulses the welding output with high peak currents (amperage) which are set at levels which will cause the transfer to go into a spray. The background current (amperage) is set at a level that will maintain the arc , but is too low for any metal transfer to occur.

53. Gas Metal Arc Welding- Applications Most common application of MIG welding is automotive repair and manufacturing . It can be even be used to reinforce the surface of a worn out railroad track. Highly economic one so it is widely used in industries. Welding tool steels and dies. YoucaN

54. Gas Metal Arc Welding- Advantages No flux is used so no need to clean. Produce very high quality weld Weld zone is visible No possibility of cracks. There is no frequent change of electrode, so it is more efficiency. Easily automated. YoucaN

55. Gas Metal Arc Welding- Disadvantages Weld surface must be clean and free from oil, grease, paint. On site welding is difficult one. Difficult to weld in small corners Equipment is costly Less portable one YoucaN

56. TIG MIG Non consumable electrode Tungsten electrode Electrode only generates arc and does not melt. Water cooled torch Used to join dissimilar metals. Join thin plates Filler rod is used Consumable electrode Bare welding wire made of desire composition Electrode generates arc and melts Water or air cooled torch Used to join similar metals Widely used for thick plate joining No filler rod used YoucaN

57. Video 5. GMAW MIG Welding _ Wire Feed Welding (go to 2 min 25sec) 6.MIG_Welding_Principles YoucaN

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