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04, Apr 2021 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 at the end of the article are tables that include 67 types of different welding processes, some of which work on melting metals, methods, pressure, but the well-known 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

The truth is that skilled workers and technicians use different regional terms in all businesses for the aforementioned operations and the topic differs from one country to another, for example the GTAW process called TIG in Europe or argon welding in Egypt and generally when you start working you will get to know all the verbal terms in your area, but you should Use formal terms whenever possible. Here is a simplified explanation of the operations

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.

The figure above is an illustration of the SMAW welding machine, which is very simple compared to other equipment, as it consists of a transformer, two electrical cables, a workpiece clamp and a pole ratio.
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 mouth of the welding gun, and it works to prevent and protect the molten metal from air pollution, and a remote control unit can be added at the feet or thumbtacks 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 as shown in the following figure
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, GTAW - TIG welding is used on Some metal alloys for example titanium welding.
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 constructed 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 welding, then the protective gas flows from the cavity of the gun to work to protect the molten weld from air pollution .
GMAW metal arc welding is the fastest and most economical welding process, and it is possible to produce very long welds quickly and in record time. It does not require cleaning after the welding procedure. You can use it on light and thick metal alloys by making some simple changes in the welding preparation.
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 as shown below. 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 estimate that it has its own method of protection.

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 / Watch by comparison with GMAW which deposit 4 kilos thus

FCAW and GMAW processes are completely different, but they use almost the same equipment and are very suitable for large projects and restructurings, and they are classified as automatic or semi-automatic operations and are the first choice for most industries because they are economically inexpensive and their results are very good.
Oxyacetylene Welding, Brazing

Oxyacetylene welding is referred to for short as OAW, and welding by brass with a torch brazing gun is referred to as TB.

The aforementioned processes use the same equipment as shown in the figure below. In TB welding the torch gun is used at a high temperature by burning oxygen and using fuel gas is usually acetylene, however it is possible to use other combinations of fuel gas with oxygen.
In welding processes, the base metal is melted and the filler metal is manually added to reinforce the welding, and the addition of the flex material is not required. Kind.
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.

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 steel.

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 tip of the torch, as shown in the figure below.
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 cutting can be done at some very high speeds and it is often used 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.