Welding is the best economical way to permanently deliver materials and metals in some of them. It is the only stable way to fuse more than one piece of metal to make it a single piece.
There are four basic factors that all unite to produce welding as follows:
▪️ Availability of minerals – or other substances.
▪️ Availability of the high heat required for the melting process.
▪️ Availability of filler materials such as electrodes or welding wire.
▪️ Availability of auxiliary materials such as gas, flex or protection and shield gas.
There are many methods and types of welding processes, some processes cause sparks and some do not require excessive heat. And welding operations can be performed anywhere, outdoors, indoors, underwater, or even in outer space for building space stations or maintaining spacecraft.
_ Definition of welding.
It is defined by the AWS as the adhesion of materials by the method of molten fusion when the basic materials are melted to form welding beads, and this is done by heating the materials to reach the required welding degrees or by applying thermal pressure or by using filler materials, welding is simply defined as meeting two edges by applying heat High by using fillers or single pressure to form one piece.
▪️ When there is enough energy available, the body temperature rises to a temperature too high to cause it to melt.
▪️ When enough pressure is used to force the pieces to fuse together to form a single surfaceIt is important to know that filling the gap between two joints of a specific material is considered cold welding.
▪️ It is important to know that welding can be applied to non-metallic materials such as plastics, ceramics, and glass.
_ Welding uses.
Modern welding techniques are used in the construction of many products, for example,
1. Space stations.
2. Merchant ships.
3. Pressure vessels.
4. Bridges, and entertainment venues.
Generally, welding is used to manufacture new equipment used in industries. Welding has played a large role in the manufacture of aircraft manufacturing machinery, which enabled designers to design commercial and military aircraft in terms of strength to weight ratios.
And it does not stop there, welding is used in the automotive industry, agricultural equipment, household appliances, components of computers, mining and exploration equipment, railways, furnaces, air conditioning, nuclear components and hundreds of other products and we have been associated with them in our daily lives in communications and dental care installations.
_ Welding and cutting operations.
Welding processes differ greatly in the way in which heat and pressure are applied together or separately or the type of equipment used, and it includes 67 types of different welding processes, some of which work on melting metals, methods, pressure, but the famous processes are:
▪️ OAW oxygen welding.
▪️ SMAW shielded metal arc welding.
▪️ GTAW Tungsten Electric Arc Welding.
▪️ GMAW gas electric arc welding.
▪️ FCAW fused arc welding.
▪️ TB Oxy Welding Torch.
▪️ PAC plasma arc cutting.
▪️ OAC cutting.
_ Here is a simple explanation of the operations.
▪️ Shielded metal arc welding – SMAW.
Also known as manual metal arc welding, it is referred to by an abbreviation of MMA or MMAW, and it is usually called stick welding, which is the manual method of using electrodes protected by the flex material with a length of 14 inches or 35 centimeters. The idea is to conduct current between the electrode and the metal section to create the electric arc and when the arc melts the end of the electrode becomes a part From the filler metal, then the arc evaporates the solid flex material in the form of a gas cloud to protect the molten weld metal and the object depends on the type of electrode used.
▪️ Gas tungsten arc welding – GTAW.
GTAW electric arc welding is known as argon welding or using inert gas in ISO in English tungsten inert gas welding TIG, which is a manual method. When heat is generated, an arc is created between the tungsten electrode and the work piece and the arc works to melt the base metal and the end of the filler metal (tungsten) and it is manually dipped in Fused welding joint basin.
Then comes the function of the gas flowing from the nozzle of the welding gun, and it works to prevent and protect the molten metal from air pollution. The remote control unit can also be added at the feet to allow better control for the technician (operator) Often this switch is used to control the start and stop of the electric current And make adjustments in energy levels.
GTAW – TIG welding is cleaner than all manual welding processes, and since it does not use the flex material that cleans and protects the face of the weld, the finished part and the filler metal on the surface of the welded area must be cleaned of oxides, oils, dirt, etc. so as not to cause contamination of the weld.
GTAW – TIG welding also requires a high level of skill compared to other manual welding processes and although the process is very slow, it is still required for its high potential in producing high quality welding in practical applications where welding quality is the basis.
▪️ Gas metal arc welding – GMAW.
GMAW is known in ISO and British code as metal inert gas welding – MIG or METAL ACTIVE GAS WELDING – MAG (inert – active).
Where the electrode (wires) is fed automatically and continuously through a pulley through the cables and exited through a welding gun. Gas then flows through a separate tube in the cable assembly and out of the barrel of the gun, but around the solder wire.
GMAW is produced when the arc is created where the blasted welding wire is melted continuously and with the same heat melting the base metals, then the molten filler metal moves to the joint basin and becomes part of the weld, then the protective gas flows from the cavity of the gun to work to protect the molten weld from atmospheric pollution factors.
▪️ Flux cored arc welding – FCAW.
FCAW is an automatic or semi-automatic process that is very similar to the same process as GMAW or MIG, and almost the same equipment can be used . The only difference that makes FCAW unique is the welding wire (electrode) is hollow and filled with flexo material instead of gas. Shielding and therefore we can say that it has its own method of prevention.
FCAW also provides greater penetration to work on thicker welding joints and works in all directions and all welding positions. When the arc is created, the current melts the welding wire and the base metal, then the flex material begins to form a gas cloud that protects the welding surface through its interference and penetration into the molten weld metal. The suspended impurities are collected and soldered, then they float to the surface to form a layer of slag during the cooling process.
The flowing flex material also allows the cooling process to slow down, which makes the welding more durable and stable. Despite this, the slag in FCAW welding must be cleaned after each stroke is completed, and what distinguishes this process is the production of high-quality welds and fast performance as it can deposit about 10 kilograms of filler material / The watch is compared to GMAW which deposit 4 kilos and therefore does not require more skill.
▪️ Oxyacetylene Welding, Brazing.
Oxyacetylene welding is referred to as OAW and torch brazing is referred to as TB.
▪️ Thermal Cutting Processes.
There are a number of thermal cutting processes such as oxyfuel cutting, referred to as OFC, plasma arc cutting and referred to as PAC, which are the most common processes in most welding fields, however there are air carbon arc cutting and the use of a laser beam. cutting.
1. The OFC cutting uses the same equipment shown in the figure above with changing the type of flame gun, which heats the surface of a piece of steel, directing a strong stream of oxygen to a specific point, which leads to burning the hot steel piece, creating a gap or cut. The gap causes a very rapid oxidation of steel metals at high temperatures, and with the continuation of the movement in the direction, the metals are cut. This technique can also be used on certain types of metal alloys of solid steels.
2. Plasma arc cutting (PAC) The plasma arc uses a solid column that is highly ionized and a type of extremely hot gas that instantly vaporizes the metal being cut. Most of the ionizing plasma is formed when high pressure air is directed through a very small opening between the tungsten electrode and the torch tip.
As the air ionizes, its temperature rises and is blown out of the tip of the flame at supersonic speeds. Also, PAC does not depend on the rapid oxidation of the metals being cut as it is by the cutting by oxygen OFC, so any metal or high-thickness metal alloy can be shredded.
The PA plasma arc cutting equipment consists of torch (transformer) power supply, plasma cable with working wire, clamp and air supply. Some PA equipment also has stand-alone air compressors. Since the cutting process can be performed at some very high speeds and it is used mostly on automatic cutting machines, the high speeds and low heat input help reduce the distortion of metal parts and edges that are a problem in OFC.
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