Introduction to welding

Suitable for Student of Diploma Civil Engineer CTEVT

1. Introduction to Welding Er . Mani Das Civil Engineer TJSS (CTEVE) 9866019982 1

2. Introduction to welding Welding  is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool causing fusion . 4 Popular Types of Welding Procedures Shielded Metal Arc Welding (SMAW) With this particular type of welding, the welder follows a manual process of stick welding. ... Gas Metal Arc Welding (GMAW/MIG) This style of welding is also referred to as Metal Inert Gas (MIG). ... Flux Cored Arc Welding (FCAW) ... Gas Tungsten Arc Gas Welding (GTAW/TIG) 2

3. Arc welding Arc welding  is a  welding  process that is used to join  metal  to metal by using  electricity  to create enough heat to melt metal, and the melted metals when cool result in a binding of the metals. It is a type of welding that uses a  welding power supply  to create an  electric arc  between a metal stick (" electrode ") and the base material to melt the metals at the point-of-contact. Arc welders can use either  direct  (DC) or  alternating (AC) current, and consumable or non-consumable  electrodes . 3

4. Electric power needed for welding SAFETY ELEMENTARY ARC WELDINGP the type of electric welders most likely to be used will be the 240 volt a.c machine , which is capable of an output current of 130 amperes with a voltage across the arc of approximately 24 volts. These machines are potential source of electric shock, which can kill All welding machines electric welding leads and fittings are to be checked or tested every four month by a certified electrician who shall fix a metal tag consisting of date showing when next inspection is due. 4

5. Welding rods The welding rod is the piece of wire connected to the welding machine. A current is fed through this wire, which helps to join two pieces of metal together firmly. In the field,  welding electrodes  are usually referred to as " welding rods " so It will use that term here. "Stick  Welding " is also the term of choice in the field for SMAW, the acronym for Shielded Metal Arc  Welding . Stick  welding  used to be done with a bare  welding rod . 5

6. Welding rods 4 Different Types of Welding Rods 6010 arc  welding rods  are most commonly used for  welding  root passes in pipe and even for the fill passes on pipelines . 6013 arc  welding rods  are the farmers  welding rod  and the  welding rod most people use first when learning to  weld . 7018 . This is a very versatile type of welding rod and is a little easier to use than 6010. ... 308L AC/DC. This rod is used to weld stainless steel and is resistant to cracks and corrosion. ... 24 AC/DC . 6

7. Welding safety rules Basics ALWAYS wear a proper face shield (Helmet). ALWAYS wear close-toed shoes (Leggings). Light rays may cause injury by burning the exposed body parts of the body so ALWAYS wear a long-sleeved, non-flammable shirt (Apron). ALWAYS wear proper  welding  gloves . The fume from material such as zinc(galvanizing) tin, brass and lead are toxic to breath, Thus mask is mandatory, ALWAYS wear ear protection (earplugs or muffs) to prevent sparks from entering your ear canal . Keep all flammable material far from welding area sucg as petroleum products. Know where the fire extinguisher is located. 7

8. Arc welding equipment’s , accessories and protective gear The various equipments required for electric arc welding are: Welding Machine: The welding machine used can be A.C. or D.C. welding machine. ... Electrode Holders : ... Cables  or  Leads : ... Cable Connectors  and Lugs: ... Chipping Hammer : ... Wire Brush, Power Wire Wheel: ... Protective  Clothing : ... Screen or Face Shield: 8

9. Arc welding equipment’s, accessories and protective gear The various equipments required for electric arc welding are : WELDING CABLE MARIGASES WELDING CABLE is black neoprene sheathed cable, with high f`ity and copper conductor. Highly resistant to oil, water, flame and abrasion. It is available in cross section areas 50 and 70mm². CABLE CONNECTORS MARIGASES CABLE CONNECTORS ensure good electrical conductivity and are suitable for use with either copper or aluminium cable, providing a quick, watertight fitting of cables on sight. The connector is distinguished into two part as Male and female connectors. ELECTRODE HOLDERS & GROUND CLAMPS have knurled ( पेच कस्न मिल्ने) handle providing a firm grip and good balance. Designed to withstand heat, with shielded spring to prevent damage from spatter and fixing by means of a bolt . FACE SHIELDS PROTECTIVE CLOTHING is made from specially treated soft leather to ensure maximum safety and comfort. They provide full protection against heat, falling sparks and slag, under the toughest conditions. WIRE BRUSH Ideal for cleaning before welding and also de– slagging . 9

10. Types of Welding Different types of welding and what they are used for MIG Welding . MIG welding is one of the easier types of welding for beginners to learn. ... Stick Welding. Stick welding, also known as Arc welding, is doing it the old fashioned way. ... TIG Welding : Gas tungsten arc  welding  (GTAW), also known as tungsten inert gas ( TIG )  welding , is an arc  welding process that uses a non-consumable tungsten electrode to produce the weld . Plasma Arc Welding. ... Electron Beam and Laser Welding. ... Gas Welding. 10 Stainless steel TIG welding

11. Electron Beam Welding 11

12. Laser beam welding Laser beam welding is a welding technique used to join pieces of metal or thermoplastics through the use of a laser. The beam provides a concentrated heat source, allowing for narrow, deep welds and high welding rates. The process is frequently used in high volume applications using  automation , such as in the automotive industry. It is based on keyhole or penetration mode welding. 12

13. Gas Welding Oxy-fuel welding  (commonly called  oxyacetylene welding ,  oxy welding , or  gas welding  in the U.S.) and  oxy-fuel cutting  are processes that use fuel gases and oxygen to  weld  and cut metals, respectively. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen- acetylene  welding in 1903. [1]  Pure oxygen, instead of  air , is used to increase the  flame temperature  to allow localized melting of the workpiece material (e.g. steel) in a room environment. 13

14. Welding Technique 14 Weld Types and techniques

15. Weld Technique 15

16. Principle of gas welding What is principle of gas welding? Principle :  Gas welding  is a most important type of  welding  process. It is done by burning of fuel  gases  with the help of oxygen which forms a concentrated flame of high temperature. This flame directly strikes the  weld  area and melts the  weld surface and filler material. 16

17. Forge welding Forge welding  (FOW) is a solid-state  welding  process [1]  that joins two pieces of  metal  by heating them to a high temperature and then  hammering  them together. [2]  It may also consist of heating and forcing the metals together with presses or other means, creating enough pressure to cause  plastic deformation  at the weld surfaces. [3]  The process is one of the simplest methods of joining metals and has been used since ancient times. Forge welding is versatile, being able to join a host of similar and dissimilar metals. With the invention of electrical and gas welding methods during the  Industrial Revolution , manual forge-welding has been largely replaced, although automated forge-welding is a common manufacturing process . Many metals can be forge welded, with the most common being both high and low- carbon steels .  Iron  and even some  hypoeutectic   cast-irons  can be forge welded. Some  aluminum alloys  can also be forge welded. [13]  Metals such as  copper ,  bronze  and  brass  do not forge weld readily 17

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