Welding And Welding Types

WELDING 

“ Welding is a process of permanently joining two metals together with the application of heat”.

                                     Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing fusion, which is distinct from lower temperature metal-joining techniques such as brazing and soldering, which do not melt the base metal. In addition to melting the base metal, a filler material is typically added to the joint to form a pool of molten material (the weld pool) that cools to form a joint that is usually stronger than the base material.Pressure may also be used in conjunction with heat, or by itself, to produce a weld.

 Welding process can be classified as :

1. Gas welding - Oxy acetylene gas welding, Hydrogen gas welding.
2. Arc welding - Metal arc welding(SMAW ), Gas metal arc welding, (MIG, MAG) Tungsten inert gas welding, (TIG) Submerged arc welding,(SAW ) Flux cored arc welding(FCAW ), Electrode slag metal arc welding, etc
3. Resistance welding - Resistance but welding, seam welding, spot welding, percussion welding.
4. Thermit welding - Heat is produced by exothermic chemical reaction.
5. Solid state welding - Forge welding, Friction welding, Pressure welding etc
6. Special welding process - Electron beam welding , Plasma arc welding, diffusion welding, Ultrasonic welding process. Under water welding. etc.

 

Joining Metals:

                               As opposed to brazing and soldering, which do not melt the base metal, welding is a high heat process which melts the base material typically with the addition of a filler material. The high heat causes a weld pool of molten material which cools to form the join, which can be stronger than the parent metal. Pressure can also be used to produce a weld, either alongside the heat or by itself. It can also use a shielding gas to protect the melted and filler metals from becoming contaminated or oxidized.

Joining Plastics

                                Plastics welding also uses heat to join the materials (although not in the case of solvent welding) and is achieved in three stages. Firstly, the surfaces are prepared before heat and pressure is applied and, finally, the materials are allowed to cool to create fusion. Joining methods for plastics can be separated into external or internal heating methods, depending on the exact process used.

Joining Wood

                                      Wood welding uses heat generated from friction to join the materials. The materials to be joined are subjected to a great deal of pressure before a linear friction movement creates heat to bond the work pieces together. This is a fast process which allows wood to be joined without adhesives or nails in a matter of seconds.

Weld Joint:

                             A weld joint must be designed to withstand the forces to which it is expected to be subjected to during its service life. This means that the design of the joint is determined by the type and magnitude of the load that is expected to act on the weld. Certain types of welding joints are designed to withstand extreme shear loads, while others are designed to withstand extreme torsional loads. Types of joints used for welding are butt, lap, corner, T, and edge.

Common Joint Configurations

Butt Joint

                                 A connection between the ends or edges of two parts making an angle to one another of 135-180° inclusive in the region of the joint.

T Joint

                                A connection between the end or edge of one part and the face of the other part, the parts making an angle to one another of more than 5 up to and including 90° in the region of the joint.

Corner Joint

                                     A connection between the ends or edges of two parts making an angle to one another of more than 30 but less than 135° in the region of the joint.

Edge Joint

                          A connection between the edges of two parts making an angle to one another of 0 to 30° inclusive in the region of the joint.

Cruciform Joint

                                      A connection in which two flat plates or two bars are welded to another flat plate at right angles and on the same axis.

Lap Joint

                                       A connection between two overlapping parts making an angle to one another of 0-5° inclusive in the region of the weld or welds.

MIG Welding

                                         MIG welding is one of the easier types of welding for beginners to learn. MIG welding is actually two different types of welding. The first uses bare wire and the second flux core. Bare wire MIG welding can be used to join thin pieces of metal together. Flux core MIG welding can be used outdoors because it does not require a flow meter or gas supply. MIG welding is usually the welding of choice for DIY enthusiasts and hobby welders who don’t have the money to spend on expensive equipment.

Stick Welding

                                         Stick welding, also known as Arc welding, is doing it the old fashioned way. Stick welding is a bit harder to master than MIG welding, but you can pick up a stick welding equipment for very little if you want to have a go at home. Stick welding uses a stick electrode welding rod.

TIG Welding

                             TIG welding is extremely versatile, but it is also one of the more difficult welding techniques to learn and Lincoln Electric TIG welders are skilled individuals. Two hands are needed for TIG welding. One hand feeds the rod whilst the other holds a TIG torch. This torch creates the heat and arc, which are used to weld most conventional metals, including aluminum, steel, nickel alloys, copper alloys, cobalt and titanium.

Plasma Arc Welding:

                                       Plasma arc welding is a precision technique and is commonly used in aerospace applications where metal thickness is 0.015 of an inch. One example of such an application would be on an engine blade or an air seal. Plasma arc welding is very similar in technique to TIG welding, but the electrode is recessed and the ionizing gases inside the arc are used to create heat.

Electron Beam and Laser Welding

                                  Electron beam and laser welding are extremely precise, high energy welding techniques.

Gas Welding

                                   Gas welding is rarely used anymore and has been largely superseded by TIG welding. Gas welding kits require oxygen and acetylene and are very portable. They are still sometimes used to weld bits of car exhaust back together.

Safety

                    All welders need to respect the job and the equipment being used. The following is a list of safety equipment and precautions.

• Wear welding gloves.
• wear eye protection for arc type welding
• Keep work area clean and flammable free.
• Wear welding helmet a proper face shield.
• Always wear close toed Shoes.
• Wear long- sleeved, non flammable shirt.
• Always wear ear protection (ear plug or muffs) to prevent sparks from entering your ear canal.

Welding Safety Equipment.

Welding Holder.

Welding Holder

Welding Goggles

Welding Helmet:

About Us

Hello Friends Welcome you to online tutorial Thermal Power Tech. This Website create For explains about thermal power plants knowledge. Here I explain you basics as well as advanced concept. It's a great platform to knowledge who working in thermal power plants. It's very Useful For Boiler operation Engineer(BOE), 1St Class, 2nd Class Attendant, Turbine Engineer, Oilman, Water Chemist and technical students. 


If you get any benefit from my videos then please LIKE them, SHARE them & SUBSCRIBE my channel because i regularly uploads Information and  videos here.