Posts Tagged ‘MIG welding’

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Angle of the Dangle: Resolving welding issues with torch angle adjustment

Thursday, October 27th, 2011

A new weldor can often be plagued with curious and aggravating weld issues that often lead to a great deal of frustration. Even occasionally it will occur with seasoned veterans of the welding field as well. Often times occurring after a long day of welding or when fatigue is likely to set in. These symptoms are not necessarily exclusive to only one type of weld process. They can occur while stick, mig, or tig welding when conditions are right. Symptoms can include inconsistent porosity issues, slag or silicone trapped in the toes of the weld, inconsistent weld bead formation, without fusing on both sides or piling of the weld on one side or the other, dirty looking welds or even large amounts of spatter.

All these issues can usually be traced to improper torch angle. A weldor has to monitor two angles of the torch position relative to the work surface and the weld.

1.  The torch angle relative to the direction of the weld. If TIG welding, particularly noticeable in aluminum, a steep angle greater than 15 degrees from vertical can result in a siphoning effect with the gas flow, pulling in air from behind the weld in to the molten puddle. Usually the angle should be with the torch reclining toward the weld area already welded, with the tungsten pointed toward the front edge of the puddle. Also, the arc can be projected too far forward creating instability issues. The weldor can suffer similar issues while welding MIG as well. However, the torch can be pointed either in the pushing or pulling direction. Whether a forward or rear leaning approach is taken, the penetration and weld width will change. While stick welding too great of an angle causes multiple symptoms, including porosity, and weld rolling into the toes of the weld. In general the torch angle should “lead” the weld, and the torch should seem to be dragging the weld along. Again the 15 degree rule should apply.

2.  The angle relative to the sides of the weld should be monitored as well. This second plane is responsible for even distribution of the heat. Improper fusion of the weld will result or overheating of one side of the metal can be seen by following the heat lines. This angle can be manipulated however, to join dissimilar thicknesses by focusing more heat on the thicker material. However, when joining the same thickness of material the torch should be held vertical as possible to the weld with the torch/electrode even distanced from either side of the weld. This applies to TIG, MIG and Stick processes of welding.

As a new weldor, if you suspect you are seeing transient problems, inspect your torch angle. Many problems can be solved by concentrating on the torch angle. If they don’t resolve, then you should proceed to suspecting other causes of the problem such as contaminated gas, or dirty metal, or insufficient gas flow.

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Polarity: When should it be reversed? Part 2

Wednesday, October 12th, 2011

Using correct polarity makes the difference between a quality weld, and one that is porous and weak, or one that gets proper penetration, or one that barely gets any at all. Beyond the confusion of the terms, it is often confusing to know just when to use what polarity.

While stick (SMAW) welding, the great majority of welding rods require a positive polarity. In fact nearly all welding rods run primarily with positive, (reverse) polarity. With a few exceptions, in the case of running on thin sheet metal, you should always run with reverse polarity.  Since the term “Reverse” may be confusing, just always think “positive torch” and you should be ok. MIG welding is always going to be positive polarity. Some people confuse MIG with flux core welding.  They are not the same, though the equipment used can be nearly the same or identical. Flux core uses a wire that contains a powder flux in the center of the wire. It has its advantages in windy conditions, and offers go anywhere performance. While not necessarily better or worse than the MIG process, it does utilize straight polarity, just the opposite of MIG. There may be some wire manufacturers however that recommend positive polarity, so be sure to check the label. One thing to note, MIG and Flux Core wire do not have “optional” polarity with the same wire. If its positive, it will only run successfully on positive. Dual shield wire utilizes the best of MIG and Flux Core by using a flux wire and shielding gas. Always follow the polarity recommendation of the wire manufacturer of course, but generally dual, or outer shield wire uses reverse polarity.

TIG is the exception and is the process where it will always weld with the torch in the negative terminal (even if welding in AC mode there are reasons to keep the torch plugged into the negative side). Years ago, DC positive was used for welding aluminum, but penetration was very poor, and it required enormous diameter tungsten to weld at relatively low amps due to heat being maximized on the tungsten tip instead of the base metal.  Since aluminum welding is so easily accomplished with AC tig units with either high frequency overlay or inverter style welders such as the Everlast PowerTIG series,  DC negative torch polarity is the only one used.

Whatever the polarity, you may need to employ some sort of memory device to help you remember the polarity terms. Even if you have to write a note on your welder to help you remember the “torch” side that you will use, it will help you in get it right, and keep frustration down to a minimum.

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Polarity: When should it be reversed? Part 1

Monday, October 10th, 2011

Any one that has been around welding for a short period of time knows a little about the term “Polarity”.But quite a few new comers find the correct use of polarity a confusing issue, though it need not be.  A lot has been written on the internet about polarity, and this blog will undoubtedly add to that information. But, hopefully it’ll be easier to understand than some of the other ponderous articles written about it.

Polarity ?

Polarity ?

Polarity is simply a term to describe the whether the electrode is a cathode or anode.  Quite simply it refers to whether the electrode is emitting (negative polarity) or receiving electrons (positive polarity). These terms are related to DC welders only. Welders that output AC current have no need to refer to polarity.  So if you are welding with an old AC buzz box welder, polarity is of no consequence to you.  But if you are welding with new inverter welder, or even an old DC transformer welder, it is.  Sometimes you may see the terms DCEP or DCEN.  These refer to Direct Current, Electrode Positive, or Direct Current Electrode Negative. Polarity is always marked  on a DC welder  and will usually bear a simple negative (-) or positive (+) sign.   Whenever a polarity change is required, the electrode (sometimes referred to as a torch) should be inserted into the side with the marking that corresponds to the polarity recommended.

Simple huh?  Well, not that simple.  A lot of old texts and “old school” welders will often refer to the terms of “Straight Polarity” and “Reverse Polarity”. Straight polarity refers to negative polarity. Reverse polarity refers to positive polarity. While that may seem to make sense, if you think about electrons always flowing from negative to positive poles, it is confusing when it is applied to several different welding processes such as stick and MIG welding.

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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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X-ray welding

Thursday, June 2nd, 2011

X-ray welding is one of the latest advances in welding technology. Just like the laser beam welding and the electron beam welding, in this type of welding, the thermal heat that is required for the weld is produced with the use of a focused high powered X-ray beam. This high powered beam will initiate a localized melting of the metal that will form the weld once it is cooled down. This process like the electron welding and laser welding again increases stability and is extremely fast. Also the accuracy of the weld is tremendously increased due to the high focus of the beam. However, this shares a common limitation. If the energy is not enough for the beam to penetrate the metal then it would form a molten pool of the metal on the surface. To overcome this, most often, a keyhole is formed in the joint that would let the heat penetrate the metal of the joint.

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The significance of MIG Welding Gun

Wednesday, March 23rd, 2011

The welding gun is single most important component when it comes to welding. Without which welding becomes absolutely impossible irrespective of what kind of welding technique you pursue. Hence much care should be directed towards the welding gun when it comes to maintenance. The wire feeds through to reach the contact tip or nozzle which allows the welding arc to weld the pieces together. It is very important that the wire feeds through smoothly and comfortably. Any obstruction will cause the arc to behave inconsistently and erratically which in the end results in poor welding and wastes materials used for welding. It is necessary to have a constant arc voltage to reduce spatter.

The erratic nature is usually a result of wear and tear or dirt issues involved with the welding gun. Thus the welding gun should be thoroughly checked and maintained regularly. If the factory is located in a dusty area such as in rural ones, there are more chances of dust entering into the workshop and accumulating here and there disrupting our work by covering the equipments with dust. For this reason alone, it is important that the workshop is built with concrete floor. The drive rollers of the wire feed mechanism often gets covered with dust and spatter particles which are mostly metallic by nature. These residues work its way down the gun cable and into the liner. And over a period of time the internal resistance increases by which the wire will fail to feed the welding gun. It is important that you regularly maintain your equipments to avoid all these issues.

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Power arc welding equipment

Wednesday, March 9th, 2011

The power arc welding process is used for heavy welding applications. This process is generally used in process like shipbuilding, on the farm or for pipelines. If you are a welding enthusiasts and want to take your welding skills up another level then you should consider power arc welding.For power arc welding you should consider power arc welding. This will help you get the perfect wield on those heavy duty applications. Some of this equipment is versatile so you can also incorporate TIG welding process with the equipment. You should make sure you purchase the TIG welding package along with the power arc wielding package. This will ensure that you can carry out a variety of welding process with the equipment. Therefore if you ever decide to make your hobby a steady source of income, you will not have to purchase new equipment again. One thing that you can look out for when you are buying such equipment is make sure that your machine has the 6010 port. This port enhances the performance of the rod for such welding purposes. The new lines of DC welders are leading the market today with their optimum welding performance.The power arcs are a reliable performer that has satisfied clients from all over the world today.

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MIG welding equipment

Friday, March 4th, 2011

MIG welding is also known as metal oxide inert gas welding. It can be a semi automatic or an automatic arc welding process. There are many units available by many manufacturers today that cater to MIG welding. You should be sure as to where you choose your equipment that you want to buy from however. Normal parameters that you should look for your set up are if it is portable.

It should be able to fit in your workshop. Also the roll capacity of your equipment is important. For most operations, a 12lb machine should be good enough to keep you running back for more wire. Also if the unit has a flux core with optional drive rolls then it should be a good bargain for you.

Normally these machines also come with a spool gun that is attachable. This will help to weld materials like aluminum. Also if you are going out to buy such a machine, make sure that you look out for the arc force control feature. There are affordable pulse MIG welding machines available today. These will help in precision and also not burn a hole in your pocket at the same time. Invest reasonably and you can easily find a machine that will most benefit your wielding project.

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