Types of welding

Do you fear in welding? Don’t worry, it is nothing. It is the processof inter molecular bonding of two similar or dissimilar metals byheating and brings its melting point temperature, in this conditionthe external pressure may or may not be used, or third metal vizfiller rod may or may not be used. The heating is produced by electricarc, oxy-acetylene flame or oxy-hydrogen flame etc. where the metal’send portion to be weld. The basic requirement of welding is i) heatenergy, ii) cleaning the edge before the welding, iii) atmosphericcontamination, iv) weld metal properties, v) application of pressure.Heat: During welding it should required sufficient amount of heat forfusion. Otherwise the joint may produced incomplete fusion.Cleaning: Cleaning the welding edges should be properly maintained.Because the unwanted materials are may be damaged the welding joints.The unwanted materials are- oxides, nitrides, oil, grease, dirt, sandetc. These should be properly cleaned by either mechanically orchemically.Atmospheric contamination: The main atmospheric contamination isnitrogen, oxygen and humidity. During welding flux, various inert gasor other types of gas should be used, which may helps to avoid thereaction with these contamination.Welding metal properties: It is very important for obtaining thecleanness weld joint. These processes are which can be controlled withsuccessfully- i) de-oxidizers used during welding, ii) to mixing upthe alloy in filler rod, iii) by the controlling of base metalcomposition, iv) by the post weld heat treatment.Application of pressure: In few welding process the sufficient amountof pressure is required for weld joint. This pressure may be obtainedfrom mechanically, pneumatically or hydraulically.Advantages of welding: a) Similar or dissimilar metals can be joining.b) The joint can produce same or more strength than base metals. c)The welding machine portability is the good advantage for anywherewelding. d) The welding can easily performed in very big size likestructure under budget. e) The welding is the only one process whichcan make joint the broken parts easily. f) It has extra facility thatthe joint can performed under water.Disadvantages of welding: a) Highly trained persons are required forgood welding. b) Initially investment cost is very high. c) Duringwelding the metallic structure of base metal may be changed for hightemperature. d) Often heat treatment may require after weldingprocess. e) In welding the edge preparation should required, so morethan one man power is required. f) The welding equipments handlingrequired with carefully. g) The welder should have sufficientknowledge about general electric. h) The very dangerous ultravioletray and fumes are produced, so safety should be taken properly.Classification of welding: There are different types of weldingprocess are classified into two main groups. One is fusion and anotheris pressure welding. The fusion welding are sub-classified in gaswelding, thermit welding, metal arc welding, carbon arc welding,atomic hydrogen welding, TIG welding, MIG welding. The pressurewelding are forge welding, spot welding, seam welding, butt welding,flash welding.The general condition of welding: The welding joint will be easy ifthe weld joint portion is cleaned by wire brush or machining or sandblasting. By these processes the unwanted materials or impurity iscleaned properly. If these impurity presences in weld pull then it maybe weakened the joint by inclusion. So the quality joint is cannot bemade. The oxidation rate is directly proportional to temperature. Mostwelding process performed in high temperature and that time theoxidation acting as a weakening agent in weld metal. This is preventedby the using of fluxes and makes a strong weld joint. In manualwelding process the flux is covered on the electrode. This flux ismelted in high temperature and covered on the weld metal. Then itcreates an artificial anti oxidation gaseous covered on weld metal.Powder type flux is used in gas and forged welding. In other weldingprocess there are used non oxidation gaseous components like Argon,Helium etc. which covered on the weld metal and prevent the oxidation.Industrial application of welding: Today the welding process is veryeasy because the machines are much modernized. So the weld joint canbe performed in any position. It has very much application in workshopto fabricate the small/big structure, repair and maintenance ofvarious components. In fabrication work there various type angle,channel or beam is used to make a structure. There may be used the nutbolt to join together, but it is less strong than welding. Thestructure can be made by casting. But this process is very expensive.In other way the welding process is less expensive, labor cost andeasy. Due to this causes the welding is very popular in fabricationindustry.