Archive for August, 2011

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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The SMAW process (part 2):

Wednesday, August 17th, 2011

The bare metal portion of the rod that is not coated is inserted into an electrode holder, sometimes called a “stinger”. The stinger holds the metal rod while welding and allows the weldor, (the person), to change the angle of the rod without having to change position or to reach around an object to weld.

The arc is struck by lightly tapping the electrode, (after inserting it into the stinger of course!), on the metal, or alternately flicking the electrode along the metal like a match. Of course, you must confine your arc striking to the immediate weld area or risk defects resulting in weld failure or rejection by an welding inspector, if you are required to submit your weld in a professional setting. As the arc is struck the electrode must be held slightly off the metal in most cases to maintain the arc and to deposit the filler metal into the weld, blending both pieces of base metal into the weld. While welding the welding rod is gradually consumed and deposited into the metal. The rod must be manually adjusted to keep the arc gap consistent. This means the rod is constantly fed closer to the puddle as it melts. It takes practice to manage this arc gap and to prevent contamination of the weld.

SMAW

SMAW

Even though Shielded Metal Arc Welding is largely a manual process it is a very sound and safe form of welding. It is also considered the most versatile and widely adapted form of welding, allowing extreme portability, while also allowing the weldor to competently weld virtually any thickness, even with smaller welders, given enough time and patience. If you’re thinking that stick welding may be what you are looking for, Everlast offers a full line of IGBT based inverter stick welders in our full line of PowerARC welders, from 140 amp to 400 amps that can manage the smallest homeowner chore to the largest industrial task. Inverters offer compact size with reduced power consumption over the heavy power hungry transformer Stick welders.

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The SMAW Process (part 1):

Tuesday, August 16th, 2011

We’ll start with our look at welding definitions by discussing one of the most common welding processes: SMAW. SMAW stands for Shielded Metal Arc Welding. It’s also commonly referred to as Stick welding, or generally as Arc welding. (This latter term can loosely apply to other forms of welding). Stick welders use a metal welding electrode as a filler material, to join the two pieces of metal together using an electric arc to heat and melt the metal into a puddle that gradually solidifies. Also called a welding rod, this metal cored electrode is usually some form of steel or stainless steel with a flux surrounding the electrode. The flux is a hard, coating that surrounds the rod down most of the length. While welding this flux serves several purposes.

SMAW

SMAW

1) To “shield” and protect the metal while welding, preventing oxygen from the atmosphere getting to the white hot metal and rapidly oxidizing the weld. An oxidized weld is weak and porous.

2) To help clean the metal and remove contaminants from the weld. As the flux interacts with the molten metal it helps to “float” out impurities. Flux components vary, while some welding rods have an iron powder base, others may have a cellulose base, all with trace amounts of other minerals or metals to form protective cocktail.

3) To provide a certain welding characteristic. Some electrodes due to their flux type weld more smoothly than others. Some because of their flux, cool more rapidly and penetrate more deeply. 

Welding electrodes are available in a variety of sizes, and purposes. After completing the weld and the weld has sufficiently cooled, the slag (consumed flux that lies on top of the weld) must be removed via chipping or a wire brush.

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How do I choose the right welder for me?

Monday, August 15th, 2011

If you’ve been thinking about buying a welder lately, then you’ve been giving some consideration to which is the best to suit your needs. If you are like most people, you may be confused by the wide array of welders on the market, and even likely by the terminology. You may be wondering what all those foreign sounding acronyms mean: SMAW,GTAW and GMAW. And you may hear terms like MIG, TIG or Stick thrown around…Without a point of reference these terms may just simply float by making your choice even more difficult and confusing. There are also many confusing numbers floating around out that with reference to welding. For example: ER6010, ER 70S-6, or even RG-60. Even the organizations surrounding and governing welding have a confusing array of Acronyms that they use. Ever hear of the AWS or the ASME? What does it mean to hold a certification, how do you get one and is it really important? Yes, there’s a lot to take in at the beginning, but after some of the confusing terms are sorted out, you’ll eventually be able to think your way through what type of welder you want for your next purchase. I’ll try to simplify and boil these down to the most basic and accurate definitions possible in the next few blogs for the most common welding terms. Hopefully you will be a more knowledgeable, informed and more comfortable purchaser. Even, though you may already know what type of welder you want and have many years of experience, there may be a thing or two you can still learn about welding and welders.

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