WELDING: Popular Types of Welding Procedures

Welding machines are powerful tools that generate heat that melts metal parts so that those parts can be joined. It is an essential tool for any construction that requires metalwork. Welding machines are categorized into heavy and light duty. The heavy-duty ones are the ones Kenyans refer to as ‘jua kali’. These are mostly used by metalsmiths and welders. Some of the light-duty welding machines are the portable ones and are unable to burn into a metal of great thickness. The following are some of the types of welding machines: MIG (metal inert gas), TIG (tungsten inert gas), stick welding (arc), plasma arc, electron beam and laser welding and the gas welding.

MIG welding is an arc welding process in which a continuous solid wire electrode is fed through a welding gun and into the weld pool, joining the two base materials together. A shielding gas is also sent through the welding gun and protects the weld pool from contamination. In fact, MIG stands for metal inert gas. The technical name for it is gas metal arc welding (or GMAW), and the slang name for it is wire welding. The MIG process enables the artist, farmer/rancher, motorsports enthusiast or DIY welder to make most types of fabrication and maintenance/repair welds on material from 24-gauge up to 1/2-inch thick. In addition to flexibility, many people turn to MIG welding because they've heard that it's an easy process to learn.

TIG welding, also known as gas tungsten arc welding (GTAW) is an arc welding process that produces the weld with a non-consumable tungsten electrode. This type of welding is also extremely versatile and two hands are needed for TIG welding, one hand feeds the rod whilst the other holds a TIG torch. TIG welding must be operated with a drooping, constant current power source - either DC or AC. A constant current power source is essential to avoid excessively high currents being drawn when the electrode is short-circuited on to the workpiece surface. TIG welders can be used to weld steel, stainless steel, chromoly, aluminium, nickel alloys, magnesium, copper, brass, bronze, and even gold. TIG is a useful welding process for bike frames, lawn mowers, door handles, fenders, and more.

Stick welding/ arc is the old-fashioned way. This method uses a stick electrode welding rod. Its versatility and simplicity makes it more popular. The anode consists of a stick or solid metal stick (therefore the name) encircled by a covering of metal powders and composites with an agent that binds them so that they can fasten to its surface. Remember that the correct term for the rod is an electrode. The electric current (AC or DC) is used to produce an electric arc between the metals you’re attaching and the electrode. This spot is known as the weld pool. Stick welding is mainly used in welding steel and iron and is widely used in the repair and maintenance industries, as well as in the construction of heavy steel structures. A good example of a stick welding machine is the inverter MMA.

Plasma arc welding (PAW) is an arc welding process similar to gas tungsten arc welding (GTAW). The electric arc is formed between an electrode (which is usually but not always made of sintered tungsten) and the workpiece. The key difference from GTAW is that in PAW, the electrode is positioned within the body of the torch, so the plasma arc is separated from the shielding gas envelope. The plasma is then forced through a fine-bore copper nozzle which constricts the arc and the plasma exits the orifice at high velocities (approaching the speed of sound) and a temperature approaching 28,000 °C (50,000 °F) or higher.

Electron beam welding (EBW) and laser beam welding (LBW) fall under the same category of power beam welding. Despite this, there are some fundamental variations between each welding process and its applications. EB welding uses a finely focused stream or beam of electrons, whereas laser welding uses monochromatic coherent light (photons). In both cases, the kinetic energy of the electrons or photons is turned into heat energy when they hit the surface of the metal. Electron beam welding is lesser-known than laser welding out of the two techniques. EBW takes place in a vacuum chamber. This aids the weld quality, as it tends to pull contamination away from the weld pool. Welding in a vacuum also results in the operator not becoming exposed to the hazardous welding environment. Shielding gas is not required for electron beam welding as the process takes place in either a low or high vacuum. Laser welding at atmospheric pressure requires a shielding gas; it is an expensive but essential consumable. Fume extraction may also be an issue. Electron beam welding can achieve deep penetration welds over a wide range of speeds, whereas laser welding with a shielding gas always requires high welding speeds due to the plume of metal vapour that forms. However, both Electron beam and laser welding are versatile, powerful, automatable processes. Both can create beautiful welds from a metallurgic and an aesthetic perspective. Both can be cost-effective.

Lastly, we have 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.

Gaining information on the types and uses of welding machines is very important to help with the purchase of a welding machine and consumables. Get in touch with us @ info@boldlimited.co.ke, Call us on 0722 525063 or visit our website @ www.boldindustrial.co.ke to get informed about our range of welding machines, accessories as well as welding safety equipment.

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