Module III Welding(1).a process used to joint two or more metal pieces.pptx

a process of joining two metal pieces

1. WELDING

2. Welding is the process of joining two metallic pieces together in permanent manner. Heat and/or pressure is applied to get the joint. •Gas welding •Arc welding •Resistance welding •Solid state welding Welding is the joining of two pieces of metal by: • Heating to temperature high enough to cause softening or melting • With or without application of pressure • With or without use of filler metal

3. ELEMENTS OF WELDING PROCESS FILLER MATERIAL  Filler materials are used to fill the space between the welded joint.  Filler material is melted and added to the joint during the welding process.  It adds strength to the joint. FLUXES Flux is a cleaning agent used to avoid the contamination of welded joint by impurities like oxides, by oxygen combined with metal during welding. Flux dissolve oxide, trapped gases and slag(impurities) from base metal .

4. Fusion welding   Fusion welding is the most common welding method. Fusion welding is a process of welding by melting one or both of a  base material  and a  filler material . Arc welding is a common example of fusion welding. Arc welding and laser welding are generally used for automatic welding using robot arms. In complicated product assembly lines, such as for automobile parts, robot and human welding are used depending on the characteristics or conditions of the process.

5. Soldering

6. Gas Welding

7. Neutral flame

8. Oxidizing Flame Carburizing Flame

9. Arc Welding

10. 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 . It is highly versatile, enabling industry professionals to join a wide range of small and thin materials. It uses a non-consumable tungsten electrode to heat the metal and can be used with or without a filler. The weld area and electrode are protected from oxidation or other atmospheric contamination by an  inert   shielding gas  ( argon  or  helium ). A  constant-current   welding power supply  produces electrical energy, which is conducted across the arc through a column of highly ionized gas and metal vapors known as a  plasma .

11. Gas metal arc welding  ( GMAW ), sometimes referred to by its subtypes  metal inert gas  ( MIG ) and  metal active gas  ( MAG ) is a  welding  process in which an  electric arc  forms between a consumable MIG  wire   electrode  and the workpiece metal(s), which heats the workpiece metal(s), causing them to  fuse  (melt and join). It employs a consumable wire that acts as both the electrode and the filler material. Along with the wire electrode, a  shielding gas  feeds through the welding gun, which shields the process from atmospheric contamination. The process can be semi-automatic or automatic. A constant  voltage ,  direct current  power source is most commonly used with GMAW, but constant  current  systems, as well as  alternating current , can be used.

12. S.no MIG Welding TIG welding 1. MIG stands for Metal Inert Gas Welding. It is also known as Gas Metal  Arc Welding  (GMAW), Metal Active Gas Welding (MAG). TIG stands for Tungsten Inert Gas Welding. It is also known as Gas Tungsten Arc Welding (GTAW). 2. It is a welding process in which electric arc is formed in between a consumable wire Electrode and workpiece metal(s). It is a process in which an electric arc is formed in between a non-consumable tungsten electrode and workpiece metal(s) 3. The type of electrode used is consumable wire electrodes. The type of electrode used is non-consumable tungsten electrode. Difference Between MIG and TIG Welding

13. 4. Most commonly it uses constant voltage, direct current power source for the welding. It can also use constant current system and alternating current. It uses constant current welding power supply for the welding. 5. The materials which it can weld are aluminum, non-ferrous materials and steels. It is most commonly used to weld stainless steels and non-ferrous metals like aluminum, magnesium and copper alloys. 6. High skilled operator is not required to perform MIG welding process. High skilled operator is required to perform TIG welding process. 7. It has high weld deposition rate. It has low weld deposition rate as compared with MIG welding. S.no MIG Welding TIG welding

14. 8. No filler metal is required. The feed electrode wire melts and acts as filler metal. It may require filler metal from outside in some cases if needed. 9. It can weld thick metal sheets upto 40 mm. It can weld thin metal sheets upto 5 mm. 10. It produces less quality of weld as compared with TIG. It produces high quality of weld because it affords greater control over weld area. 11. It uses continuous wire feed. It does not uses continuous wire feed. 12. The equipment used in MIG welding process is a welding gun, a welding power supply, a feed wire unit, a welding electrode wire and a shielding gas supply. The equipment used in TIG welding process is welding torch, non-consumable tungsten electrode, a constant-current welding power supply and a shielding gas source. S.no MIG Welding TIG welding

15. 13. It is a faster welding process. It is a slower welding process. 14. In this welding process, the use of filler metal is compulsory. But in this welding process the filler metals may or may not be used. There is no compulsion of using filler metals, it is used when required. 15.  It cannot work in any position. It can be worked in any position. S.no MIG Welding TIG welding

16. Manual Metal Arc Welding (MMAW) Process Manual Metal Arc Welding (MMAW) process also known as Shielded Metal Arc Welding (SMAW) processes are very simple to set up and use. Most of the welders have grown up using the MMAW process in villages and small towns of India. The low cost of equipment makes the process accessible to most people, and MMAW has no special requirements such as external gas shielding or high-frequency arc initiation. Sound welds are easily produced and the process doesn’t tend to result in weld defects such as lack of fusion which is common in GMAW.

17. MMAW is a welding process that creates an electric arc between a hand held, flux-coated, consumable filler wire and the work piece. The arc heat melts the parent metal and filler wire. The flux coating breaks down in the arc to produce a gaseous shield that excludes atmospheric gases from the weld zone. The flux coating also provides a de-oxidizing action and forms a slag on the cooling weld. The MMAW welding process needs a suitable and constant current power source AC or DC.

18. Where Is MMAW Used? MMAW is widely used for: Structural work Pressure vessels Piping maintenance Welding site construction General fabrication

19. CAW is a welding process in which metals are joined by an electric arc between the work-piece and a non-consumable carbon electrode. It is the first  arc welding process  that has discovered. Previously, many people were using the CAW process but nowadays the use of this  welding process  has decreased.  The main purpose behind the CAW process is to form a strong bond between the distinct metals. Here, the carbon electrode is used for producing an electric arc between the electrode and the metals being bonded.  During this welding process, a temperature more than 3,000 ºC is produced Carbon Arc Welding (CAW)

20. An electric arc is generated between the electrode and the parent metal. The heat generated due to the electric arc melts the base metal. After the solidification of the molten metal, the required weld is produced in the given region. The size of the electrode used can vary in the process depending on the generated current.

21. Advantages The equipment used in this process has a lower cost. It is easy to carry out. Anyone can perform CAW. A skilled operator is not required during this arc welding.  Very fewer distortions are produced on the workpiece.  You can easily automate this entire welding process.  Disadvantages  Sometimes, you may not get the quality weld from this process.  The carbon electrode does the contamination of the weld material with the carbides

22. Submerged Arc Welding (SAW) is a joining process that involves the formation of an electric arc between a continuously fed electrode and the workpiece to be welded. A blanket of powdered flux surrounds and covers the arc and, when molten, provides electrical conduction between the metal to be joined and the electrode. It also generates a protective gas shield and a slag, all of which protects the weld zone. Submerged Arc Welding

23. It is a welding method where this arc can travel under a layer of granular flux. In this type of welding, a tubular electrode otherwise consumable solid can be fed constantly to the weld region. At the same time, a layer of granular fusible flux can be poured over the weld zone which immersed the welding arc as well as defends it from atmospheric pollution. The granulated flux includes compounds like lime, silica, manganese oxide, calcium fluoride, etc. Whenever the flux is melted, then it turns into conductive as well as offers a current lane among the workpiece & electrode. The solid layer of flux wraps the melted metal totally and stops the sprinkle and covers the strong ultraviolet (UV) radiation vapors generated during the procedure.

24. Plasma ARC Wielding In plasma arc welding coalescence is generated with  the temperature  which is developed from a special setup between a tungsten alloy electrode and the water-cooled nozzle or between a tungsten alloy electrode and the job. In this type of winding, there are three types of gas supplies being utilized namely plasma gas, shielding gas, and a back-purge gas. Plasma gas supplies throughout the nozzle turn into ionized. The shielding gas supplies throughout the external nozzle & protects the join from the environment. Back-Purge gas is mainly used when particular materials are being used

25. The  equipment used in the PAW  includes the following. The  power supply   used in the PAW is a DC power source, and the suitable voltage for this type of welding is 70 volts or above. The typical welding parameters are voltage, current, and gas flow rate. These parameter values can be ranges like the current is 500A, voltage is 30V to 250V, the speed of cutting is: 0.1 to7.5 m/min, the thickness of the plate is up to 200mm, required power is 2KW to 200KW, the rate of material removal is 150 cm3/min, and plasma velocity is 500m/sec Current limiting resistors, as well as a high-frequency generator, are used for arc ignition. The plasma torch includes an electrode as well as water-cooling arrangement, and these are used to save the nozzle & the electrode’s lifespan from dissolving due to the extreme heat generated while welding. Shielding gas is used for protecting the arc region from the atmosphere

26. 1) Transferred PAW The transferred PAW method uses direct polarity DC current. And in this method, the tungsten electrode can be allied to the – ve terminal and the metal can be allied to the + ve terminal. The arc produces among tungsten electrode as well as work portion. In this kind of method, both arc and plasma moved toward the work portion, which will enhance the heating capacity of the method. This type of PAW can be used to join solid sheets. 2) Non-transferred PAW The Non-transferred PAW method used direct polarity  DC current . And in this method the tungsten electrode can be connected to the – ve and the nozzle can be connected to the + ve pole. The arc generates among the nozzle as well as tungsten electrode within the torch, which will enhance the ionization of the gas within the torch. And the torch will transfer the ionized gas for further procedure. This type of PAW can be used to join thin sheets. Plasma ARC Welding Types

27. Advantages of PAW The advantages of PAW mainly include the following. Power consumption   is low Welding speed is high, so it can simply utilize to join thick and hard workpieces. Penetration rate is high. It can function at little amperage. The arc arrangement doesn’t affect by the distance among tool as well as the workpiece. By using this method, the more steady arc can be produced.

28. The process is noisy. Equipment cost is high. High expertise labor required. Radiation is more. Disadvantages of PAW

29. Applications of PAW PAW can be used in industries like aerospace as well as marine PAW is used to join stainless tubes and pipes This type of welding is mostly applicable for electronic industries. PAW is mainly used to fix tools, mold and die. PAW is used to weld the turbine blade