Arc welding The fusing of two or more pieces of metal together by using the heat produced - PowerPoint Presentation

1. Arc weldingThe fusing of two or more pieces of metal together by using the heat produced from an electric arc welding machine.

2. How an arc is formedThe arc is like a flame of intense heat that is generated as the electrical current passes through a highly resistant air gap.

3. Arc welding process

4. Tungsten Inert Gas welding

5. Welding torch

6. ApplicationsAll types of metals & alloysRecommended for thin metal sheet(.125mm)Used in fabrication of missiles,air crafts,rockets& submarines

7. DisadvantagesCost of inert gasProper cleaning required before weldingRelatively slow operation

8. Metal Inert gas Welding

9. AdvantagesAll position capability  Higher deposition rates than SMAW  Less operator skill required  Long welds can be made without starts and stops  Minimal post weld cleaning is requiredMore rapid operation

10. ApplicationsPopular for non ferrous materials Al, Mg & TiUsed for thickness > 4mm

11. Submerged Arc Welding

12. ApplicationsUsed for c steel, alloy steelFor non ferrous metals like Ni, Bronze etc.

13. Electric Resistance Welding

14. Process ParametersCurrent & power supply- A.C. supply of 50Hz, with a voltage of 1-25V & a current of 100-200 AResistanceTime Interval- should be very shortPressure range-200-600 kg/square cm

15. AdvantagesVery fastSuitable for mass productionLess skills requiredEconomicalCan weld dissimilar metal

16. Spot Welding

17. ApplicationsFor C- steel sheets up to 4mm thicknessSteel plates up to 12mm thicknessManufacturing of metal containers & toysCan b used for Cu , Steel, stainless steel.

18. Seam welding

19. ProcessWelding current-5000AmpForce 6KNSpeed 12 feet/min

20. Stich welding

21. Applications & AdvantagesApplications- pressure-tight joints in containers, boxes, tubes, cylinders etc.Advantages- low cost, high production rate , suitable for automationDisadvantages- thickness limited upto 4mm

22. BUTT Welding

23. Thermit welding

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26. ApplicationsFor very thick plate & heavy sectionsFor joining rail road , pipes thick steel sectionsFor heavy casting & gears

27. Advantages & DisadvantagesSimple , fast process for similar & dissimilar metalcheapEssentially used for ferrous metal parts of heavy sectionsUneconomical for cheap metals

28. SolderingIt is a low temperature joining process. It is performed at temperatures below 840ºF for joining.

29. ClassificationSoldering ironTorchDip & waveInductionResistanceFurnace& hot plate methodSprayUltrasonicCondensation

30. Types of solderSoft solder-Pb, Tin mixtureHard solder- brass, silver, Cu solder

31. Soldering Fluid2 types- 1)which protect surface & also clean it Killed spirit(zinc chloride),ammonium chloride , zinc ammonium chloride 2)tallow , resin, Vaseline, olive oil etc.

32. Advantages & ApplicationsLow cost, simplicityGood & effective sealingRadio , T.V. setsRadiator brass tube

33. BrazingDefinition:A process which a filler metal is placed at or between the faying surfaces, the temperature is raised high enough to melt the filler metal but not the base metal.The molten metal fills the spaces by capillary attraction.Non ferrous metal = spelterM.P. of filler > 420Torch BrazingOxy-fuel torch with a carburizing flameFirst heat the joint then add the filler metal

34. Flux usedBorax,boric acidBoratesFluorideschlorides

35. Metals used for brazingCu , Cu alloys, brass, bronzeAg alloysAl alloys etc

36. Heating can be done byCoal-gas & mouth blow pipeOxy-acetylene torchOxy-hydrogen torchElectrical Resistance

37. Brazing MethodsTorch brazingFurnace brazingResistance brazingDipSalt-bathInduction

38. Advantages & LimitationsInitially CheapNo Metallurgical changesFast ,flexible & accurateSuitable for mass productionFor proper strength must be defined carefully

39. GAS CUTTINGFerrous metal is heated in to red hot condition and a jet of pure oxygen is projected onto the surface, which rapidly oxidizesOxides having lower melting point than the metal, melt and are blown away by the force of the jet, to make a cutFast and efficient method of cutting steel to a high degree of accuracyTorch is different from weldingCutting torch has preheat orifice and one central orifice for oxygen jetPIERCING and GOUGING are two important operationsPiercing, used to cut a hole at the centre of the plate or away from the edge of the plateGouging, to cut a groove into the steel surface

40. Weld DefectsUndercuts/OverlapsGrain GrowthA wide T will exist between base metal and HAZ. Preheating and cooling methods will affect the brittleness of the metal in this regionBlowholesAre cavities caused by gas entrapment during the solidification of the weld puddle. Prevented by proper weld technique (even temperature and speed)

41. InclusionsImpurities or foreign substances which are forced into the weld puddle during the welding process. Has the same effect as a crack. Prevented by proper technique/cleanliness.SegregationCondition where some regions of the metal are enriched with an alloy ingredient and others aren’t. Can be prevented by proper heat treatment and cooling.PorosityThe formation of tiny pinholes generated by atmospheric contamination. Prevented by keeping a protective shield over the molten weld puddle.

42. RollingProcess of shaping metals into semi finished/ finshed forms by passing b/w rollers

43. Process of rollingPrimary->hot->cold->Casted ingots-1.5m*1.5mBlooms- 150-400mmSlabs- b=500-1800mm;t=50-300mmBillets- 30-150mmPlates- t=6mm or >;b=1200-1400mm;l=6000mmSheets- 0.5-5.0 mm=tstrip- b<=750mm

44. Rolling process

45. Types of millsTwo high roll mill3 high roll mill4 high roll millCluster rolling millMulti high roll mill

46. Types of mills

47. Terms related to rolling

48. Defects in rollingEdge crackingFoldsAlligatoringScale formation

49. METROLOGY

50. Slip GaugesCan b used for tolerance of 0.001-0.0005mmDifferent grades available- Calibration grade Grade 00 Grade 0 Grade I Grade II

51. ComparatorsAn indirect type of instrument Enables a comparison between an item & a length standard

52. Elements of A ComparatorsA sensing deviceA magnification systemA display system

53. Types of comparatorsMechanicalElectricalOpticalPneumaticFluid displacementMechanical optical

54. Mechanical comparatorsDial indicatorsLever comparatorSigma comparatorJohanson Mikro katorRead type comparator

55. Dial gauges

56. Application- Trueness of milling m/c arbors parallelism of shaper m/c alignment of lathe m/cHaving graduations of 0.01mm or even 0.02mm

57. Lever comparators

58. Sigma comparatorsHaving a magnification of 1000:1Worktable & contact tip are inter changeableCan check a height up to 600mm

59. Electrical comparatorMagnification range-> 1100-18000Can read up to 0.0001mmAlso available with magnification of 40000

60. Optical ComparatorsHaving magnification of 1000:1Measuring range of 0.075mm

61. Pneumatic ComparatorPossible magnification is 30000:1, usually about 10000:1Used to check I.D.,O.D., thickness, concentricity, depth of blind holes

62. Fluid Displacement Comparator

63. Angular Measuring InstrumentProtectorSine BarAngle gaugesClinometers

64. Sine Bars

65. Working Principle

66. For heavy components

67. For small components

68. Angle gauges

69. Limit GaugesType->Standard gaugeLimit gaugeIndicating gaugeCombination gaugeWorkshop gaugeInspection gaugeMaster gauge

70. Standard Gauge

71. Limit gauge

72. Plug gaugesCheck whether the whole dia. is within the limit or not

73. Pin GaugeHoles to be check are larger than 75mm

74. Snap GaugeCheck the accuracy of shaft & male membersCheck the tolerance of the shaft

75. Caliper GaugeUsed for both I.D. & O.D.

76. Thickness/ Filler GaugeThe width of strip is generally available to 12.5mm

77. Radius & Screw pitch Gauge

78. Limits , Fits & Tolerance