Posts Tagged ‘gas metal arc welding’

The GMAW process (part 3):

Monday, August 22nd, 2011

In general MIG is considered a Constant Voltage (CV) process. While welding voltage does not vary, but wire speed determines the amps. As the feed rate of the wire changes, so do the amps. Many models of welders use an inch per minute scale, and others use an amp scale. Either is correct, though wire speed is the most commonly used scale. Many small and older welders don’t have a digital readout to provide an exact reading and may only carry a 0-10 scale to allow easier adjustment, without having to think about either. Generally with these settings, the weldor operates usually by sight and ear. Small inexpensive and larger transformer based welders may have taps ( a switch with preset detent) that limits the adjustments of voltage to a specific setting. The cheapest MIG welders also use taps for wire speed adjustment. Though simple to use this can be frustrating by preventing the best setting for the weld.

Many box and large chain stores offer small transformer MIG‘s that are rather inexpensive, and typically yield less than professional quality welds, especially in the hands of inexperienced users. Most of these units offered for sale use taps on at least the voltage. It’s another reason why MIG has been accused of making less than adequate welds. Not having enough adjustment can make achieving the best weld quite difficult. Quite a few customers buy them not fully realizing the expense involved in providing rolls of wire, consumables, and shielding gas. Often they turn to using Flux Core wire, which pound for pound ends up costing as much or more than solid wire with shielding gas. Everlast has produced a remarkably competitive line of MIG welders that effectively deal with many of the issues surrounding achieving quality welds with MIG. Each MIG is inverter based, which allows the MIG process to be more portable than ever. The inverter design also features a step-less design for voltage and wire speed (amp) adjustment by always allowing the setting to match the material. The design also uses digital readouts for volt and wire speed, allowin precise, repeatable settings. Additionally, each unit features inductance control (arc force) which allows the user to fine tune the arc characteristics. The heavy-duty wire drive system also feeds the wire into one of the highest quality MIG guns available on the market.

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The GMAW process (part 2):

Friday, August 19th, 2011

As already mentioned, MIG welding uses a gas or blend of gases in lieu of a flux. Usually the primary component of the gas is Argon, though CO2 is usually present for most steel applications. A triple blend of Argon, Helium and O2 may be used for Stainless Steels. While welding aluminum, pure Argon is generally used.

GMAW

GMAW

MIG is generally considered the easiest form of welding. Simply load the wire pull the trigger on the MIG gun, and weld. As long as the gun kept at a constant distance from the metal is steadily moved forward, the wire is fed automatically into the molten weld pool. How much more simple could it be? However, the confusion and misunderstanding comes in with the fact that though it is easily picked up, it is rather difficult to master. Many uniformed welders have discounted MIG welding for making weak or brittle welds. By and large, this is a rather false accusation. MIG definitely is a more rapid welding process, and does open itself up to having flaws, and voids in the weld because of it. However correctly done, MIG is just as strong as other welding processes. Though it doesn’t have the reputation of yielding pure welds like TIG welding, it can be used in almost all welding situations. The problem is that it takes correct technique and thorough metal prep to yield the best welds. Often, People who try MIG often get frustrated by the lack of fusion that can be experienced with MIG early on in the learning process and turn to the SMAW process achieve better results without as much practice. However, with correct metal prep, and technique that results from practice, a properly welded MIG weld will hold up just as well.

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The GMAW process (part 1):

Thursday, August 18th, 2011

One of the most widely misunderstood forms of welding is GMAW. Gas Metal Arc Welding is more commonly known as MIG. MIG is an older term used to refer to Metal Inert Gas(MIG) welding. Originally it was created to refer generically to a gas shielded form of welding with a semi- automatically fed solid filler wire wrapped on a roll. But as the “correct” police came about in an effort to clarify the science of welding, the MIG acronym was retired from official use to reflect a more accurate definition. Although the term is still widely accepted, the term “MIG did not allow for the fact that Carbon Dioxide, and to a lesser extent Oxygen is almost always used as a mixed component of the shielding gas, making it partially “active”, rather than “inert”. This led to the splinter definition of MAG: Metal Active Gas. So the GMAW banner accurately describes both types of operation.

GMAW

GMAW

To make matters worse, many people often confuse MIG with other forms of wire welding such as Flux Core which though may use the same or similar equipment, is an entirely different process. Flux core uses a hollow wire loaded with a flux that is used in place of the shielding gas that rises to the top of the weld pool and protects the metal while it is cooling. The gas is not used. Another form of wire welding that leads to further confusion is the dual-shield form of wire welding, which uses both a gas and a special flux cored wire to shield the weld.

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Some Facts about Gas Metal Arc Welders:

Wednesday, February 9th, 2011

Welding is the process by which two metals are joined and there are many types of welding like MIG welding, TIG welding etc to name a few. In this league there is also another particular type of welding called arc welding. If you are doing this type of welding you need to choose the correct arc welder.

Arc welders are majorly in two types- Gas metal Arc Welders and Flux-Core Arc Welders. Based on a number of factors like the material you will work on, the atmosphere you will be working in etc you have to choose the arc welder which will suit you more.

When you take the gas metal arc welder as an option you must be aware that it is very tough to use them outdoors as the gases will get blown out by the wind. The gas metal arc welders can guarantee you precision and clean welding without having any scum formation by the oxidization of metals. These welders are preferred at a lot of manufacturing and industrial outlets to work on machines, automobile etc.

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Uses and purpose of Metal Insert Gas welding:

Tuesday, June 8th, 2010

Generally welding machines are used for merging two or more materials together. The categories of welding machines are Arc welding, Mig welding, Spot welding, Tig welding and many more which are utilized for different aim. While welding you need lot of concentration and is a very hard job.

Mig welding is famous as feed welding. The full form of mig is metal insert gas. These are less expensive and consumes less time. Other welding machines consume lot of time and are more expensive than mig welding. The main reasons for using mig welding are:

• It is simple and gives high performance.
• The welding work is done in lesser time than other welding machines.
• It is capable of working with all kind of metals. For example aluminum and steel are commonly used.
• It is also known as gas metal arc welding because it can utilize any shielding gas for obtaining smooth finish.

The Mig welding are utilized by farmers, metal fabricator and house mechanics. Almost all farmers use this because it is affordable and saves time. The fabricators use this because they need to work on all metal.

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Gas Metal Arc Welding

Monday, September 7th, 2009

MIG welding is also known as Gas Metal Arc Welding (GMAW). MIG welding can weld aluminum, nickel and stainless steel etc. It is mostly used in manufacturing and commercial fabrication settings. Pros of MIG welding are – high quality welding can be done fast. There is less loss to alloying elements because shielding gas protects the arc. Minimal post weld cleaning is required. Less operator skill required. Higher deposition rates than SMAW. MIG Welding can be used for various metals and alloys. Cons of MIG welding are – It cannot weld vertical position. The equipment is complex. MIG welding consists of a welding gun, a power supply, shielding gas and wire-drive system.

MIG welding problems include Burn back, Porosity, Unstable arc, difficult arc starting and irregular wire feed. Weld discontinues are undercutting, incomplete fusion, porosity, weld metal cracks, heat affected zone cracks and incomplete joint penetration.

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What are Welding Rods?

Tuesday, July 7th, 2009

Welding rods are also known as filler metals or electrodes. It is basically a type of metal which is mostly used in the welding process to fill a joint that has to be fixed. The process of welding is very easy, a welding operator has to melt the work pieces and add a filler material, often a welding rod, to shape the molten material which after cooling becomes a strong joint.

Welding rods are available in four types. Covered welding rods are generally used in metal arc welding. Welding rod coating consists of certain compounds like rutile, calcium fluoride and cellulose, iron powder. Rutile-coated rods provide a good appearance and good quality to the weld. Stainless steel rods are used to weld steel work pieces.

Bare welding rods are basically used in gas metal arc welding or gas tungsten arc welding. These rods contain metals like silicon, manganese, titanium and aluminum which can prevent oxygen porosity. These rods have diameters ranging from 0.7 mm to 2.4 mm.

Tubular welding rods are used in flux-cored arc welding. These rods contain various metals such as stainless steel, high nickel etc. Welding fluxes are used in submerged arc welding.

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