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What Is The MIG/MAG Welding Process?

What Is The MIG/MAG Welding Process?

The MIG/MAG welding process was developed to meet the production demands of the war and post war time economies. This welding process utilises an electric arc power source, continuously fed consumable wire electrode shielded by gas. Some terms are used for the welding process such as:
• MIG – Metal inert gas welding
• MAG – Metal active gas welding
• GMAW – Gas metal arc welding

Selecting good welding equipment will make all the difference when it comes to welding. The wrong type or poor quality equipment can cause frustration, poor weld quality and waste a lot of time. Whilst a wide range of welding equipment is available the development of new technologies have made equipment easier to use and set up often by automating many features allowing the welder to concentrate on welding technique.

MIG/MAG Welding Process Description:

The MIG welding process was first patented for the welding of aluminium in 1949 in the USA. The process uses the heat that is generated by an electric arc formed between a bare consumable wire electrode and the work piece. This arc is shielded by a gas to prevent oxidation of the weld.

In the MIG process an inert shielding gas is used to protect the electrode and weld pool from contamination and enhance the arc. Originally this gas was helium.
In the early 1950’s the process became popular in the UK for welding aluminium using argon as the shielding gas.

Development in the use of different gases resulted in the MAG process. This is where other gases were used, for example carbon dioxide and sometimes users refer to the process as CO2 welding. Gases such as oxygen and carbon dioxide were added and are active constituents to the inertgas to improve the welding performance. Although the MAG process is in common use today it is still referred to as MIG welding although technically this is not correct.
The process began to prove itself as an alternative to stick electrode (MMA) and TIG (GTAW) offering high productivity and deposition rates. The process also helps reduce any weld defects from the increased stop/starts used in MMA. However, the welder must have a good knowledge of the system set up and maintenance to achieve satisfactory welds.

MIG/MAG Process Features And Benefits:

The MIG/MAG process has a number of features and benefits over other modes especially if the correct method is used.
• It can weld most commercial metals and alloys including steel, aluminium and stainless steel.
• The simple techniques are easy to learn as the constant feeding of the consumable wire allows the operator to concentrate on the arc control.
• It can be easily mechanised for repetitive welding.
• The process allows for greater speed and efficiency compared to the MMA and TIG process resulting in faster welding with reduced labour costs.
• It can be used in almost all positions.
• A wide range of current can be used for a single wire diameter allowing a variety of joints to be made without changing consumable or equipment.
• Continuously fed consumable wire reduces down time due to changeover.
• The process is a “low hydrogen” process with reduced danger of hydrogen pick up. Alloy steels are weldable with less risk of cold cracking and no special treatment of the consumables is required such as drying ovens.
• Less weld defects caused by stop starts in the weld time.
• Approximately 98% of the consumable wire is converted to weld material compared to 65% with MMA welding.
• Produces little or no slag (weld shield formation) helping reduce weld defects such as slag inclusion.
• The arc pool is clearly visible during welding.
• There is low wastage with the MIG/MAG process compared to MMA and minimal post weld clean up required saving time and reducing labour cost.

MIG/MAG Welding Tips And Guides:

Whatever your choice of power source, always read your owner’s manual. This contains important information about the correct operation and safety guidelines which should be observed.
Some quick reference handy tips for the MIG/MAG welding process are:
• When welding, try to use an electrode stick out (the distance between the weld and the contact tip) of around 6-8mm.
• When welding thin materials try and use smaller wire diameters and for thicker materials use thicker wires.
• Make sure you select the correct wire type for the material to be welded.
• Ensure the welding gun has the correct size and type of liner.
• Always ensure you have the correct size drive rolls and torch liner for the wire size selected.
• Select the correct gas to achieve the correct weld characteristics and finish.
• For optimum control of the weld keep the wire at the leading edge of the weld pool.
• Before commencing welding, ensure a comfortable and stable position.
• Try to keep the welding torch as straight as possible when welding to ensure the best feed.
• Carry out daily housekeeping on the condition of the welding torch and drive rolls.
• Keep any consumables clean and dry to avoid contamination such as oxidation and damp.
Welding Carbon Steels
In order to weld these materials you must:
• Use the correct welding gas, usually ARGON + CO2 with percentages of argon ranging from 75% upward.
• Using pure CO2 as a protection gas will produce narrow beads with greater penetration but a considerable increase in spatter.
• Use a welding wire of the same quality as the steel to be welded. It is best to always use good quality wires and avoid welding with rusted wires that could cause welding defects.
• Avoid welding rusted material or that with oil or grease contamination.

Welding Stainless
• Ensure the correct gas mix for stainless steels is used. Usually a protection gas with a high argon content containing a small percentage of O2 or carbon dioxide CO2 (approximately 2%) to stabilize the arc.
• It is important to keep the welding area clean at all times to avoid contaminating the joint to be welded.

Welding Aluminium
In order to weld aluminium you must use:
• Pure argon or argon helium mix as the protection gas.
• A welding wire with a composition suitable for the base material to be welded.
• NOTE: If only a torch prepared for steel wires is available, it must be altered as follows:
• Make sure that the cable is as short as practicable, if possible no more than 3 metres long.
• Remove the brass liner nut, gas nozzle, contact tip and then take out the steel liner.
• Insert a Teflon or carbon fibre liner making sure that it protrudes from both ends.
• Screw the contact tip back on so that the liner butts up to it.
• At the free end of the liner insert the liner nipple and O-ring and fasten with the nut without over-tighten.
• Use wire feeder rollers suitable for aluminium wire.
• Adjust the pressure exerted by the arm of the wire feeder group on the roller to the lowest possible setting.
• Consider the use of a push-pull or spool on gun type welding gun to aid wire feed consistency.
• Ensure that the contact tips are suitable for use with aluminium.
• Make sure the material to be welded is clean.
• Remember to fill the crater at the end of the weld to reduce weld defects.

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MIG Welding Problems

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The MIG-300L PRO MIG Welder has the versatility you need

The MIG-300L PRO MIG welder overall is an impressive package at a great price point, but I dug into the details to see if it’s really worth it.

Wide Power Range

With an amperage range of 40 to 300 amps, this welder handles stock 2.0mm to 16mm thick. So, this welder tackles all kinds of tasks, from customization to metal fabrication work.

Duty Cycle

For a machine priced competitively, a 80% duty cycle at 300A is impressive. You want to weld, not stand around waiting for the welder to cool. The strong MIG-300L PRO duty cycle keeps you productive.

Wide Power Input Options

The MIG-300L PRO provides versatility with three options to power up this machine. You can run on 150 – 500-volt input power.

4 Roller Drive Wire Feed

Unlike some lesser-quality welders, this machine uses a 4 roller mechanism to drive wire MIG torch lead reliably.

Inductance Control

For improved control over your arc, the MIG-300L PRO includes inductance control. This is a nice surprise for the price, and it is very useful. You can tune the arc for better penetration or make the bead wide and flat. It is up to you with a turn of a knob on the control panel.

2T And 4T Trigger Control

The MIG-300L PRO includes a 4T option, so you do not need to hold the trigger during long welds. That means your finger does not get tired, and you can move your fingers back from the heat if things get a bit too hot.

(2T is the standard mode of operation; pull and hold the trigger to start welding and release the trigger to stop. But when in the 4T mode, you pull and release the trigger to start, then pull and rerelease the trigger to stop.)

If you run a shop that deals with a wide variety of tasks, the multipurpose MIG-300L PRO MIG welder can be your go-to unit in the shop. It has a wide amperage range, allowing you to take on stock as thin as 2.0mm to 16mm.

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