Archive for the ‘Welders’ Category
Friday, February 10th, 2012
Little thought is given to joint type or design while welding on light gauge metal. Occasionally on real thin metal, a lap weld will be made or some similar accommodation may be made, of course. But overall, until the material to be welded exceeds 11 gauge material, most of the time 100% penetration can be achieved with little effort.
As metal thickness increases, beveling and grooving the plate will be necessary. Very few experienced welders would think of trying to tackle a 3/8″ weld without at least putting a simple V into the joint. Most of the time, a full 60 degree joint with a slight “land” will be made. Depending upon the thickness, a double bevel may be made as well so the joint can be welded from both sides. Joints under 3/8″ will also receive some form of beveling, whether it is a “V”, or a shallow “U” groove. On thinner metal, it may only be necessary to groove one side of the joint. On many thicker joints, a “V” grooved joint will be ground out on the back side, creating a shallow “V” or “U” to remove the first pass to eliminate possible weld defects that are trapped in the open root.
Actual determining factors in joint design, whether it is going to be welded with MIG, TIG, or Stick will depend upon the WPS or local codes, and relative position. The ultimate goal, of course, is to create the highest quality weld possible. A large thick, single pass at a high amp range will only serve to create weak welds, even if 100% penetration is able to be obtained, because of overheating the metal, and the metal cooling before all the slag can be floated out. In the groove, each pass should not be any thicker than the electrode itself, and the weld puddle no wider than 3 times the width of the electrode.
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Tuesday, February 7th, 2012
From time to time, mistakes are made in a weld seam, or a repair to a weld will be needed. It can be quite time consuming grinding and cutting the affected area to get down to good metal. Especially in a field repair situation, something may need to be rapidly cut or gouged away. The best solution is the Air-Carbon Arc Cutting torch. It’s a relatively simple process. Though it’s not as neat as a plasma or even an oxyacetylene torch, the Air-Arc process is rapid. It can remove a lot of metal in a very short amount of time. The Air-Arc process however, needs plenty of amperage to do the job properly. A simple high amp output Constant Current power source such as a stick welder is used. The usual minimum amperage required is 300 amps, though smaller electrodes will demand less amperage. The carbon arc torch is very similar in appearance to the standard tong type electrode holder. However, it also has a starting button and an air hose that provides a “jet” of air from the torch. Instead of a wire electrode, a carbon electrode is used, which provides a super hot arc. It is fairly slowly consumed, but it does wear. The arc is struck and held short while the air is turned on. The air pressure starts to wash away the metal, as the torch is held at a relatively flat angle. This is technically referred to as “gouging”. Carbon electrodes can be a little expensive, particularly the copper clad ones which last longer, and provide a little more uniformity in the cut. The torch oscillated gently around directing the arc and the air to spread out the cut. If a deep cutting action is need the torch should be rotated to a steeper angle. Slag and sparks come with the job, so extreme caution must be used to prevent the wash of slag being directed toward any flammable surface. Also good personal protective equipment is a must to prevent accidental back splash.
Tags: Arc Welder, MIG Welder, plasma cutter, TIG Welder, Welders, welding equipments for lease, Welding forum, welding machine
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Monday, February 6th, 2012
Surfacing is a process of depositing metal on items that have been worn down, or are subject to wear corrosion or other damage to help extend the life of the tool. This kind of welding is done not for creating joints or for joining metal, but for building up, and laying a protective layer or bead on top of vulnerable parts and pieces that are subject to wear such as backhoe buckets, or farm equipment plow points. More often than not, the surfacing is done to restore the metal back to the rough original dimensions, or to protect areas receiving uneven wear. There are two basic types of surfacing. The first is called hardfacing.
Hard facing generally involves the Stick or MIG process and uses special (and usually expensive) filler metal to build up the overall surface of the metal. These beads are often not laid solid across the entire face of the metal, but in random or organized patterns that intersect or overlap to provide a raid, bumpy like surface that takes the brunt of the wear or impact. Hardfacing is done to improve either abrasive wear or impact resistance of the metal.
The second method is known as “metallizing”. This is a special welding process in which nearly or all of the entire affected area is coated with molten spray of metal. This spray is used to build up the overall surface so that in many cases the original dimensions can be restored to the metal, such as in a crankshaft in an engine is deeply scored or overly worn on the journals. A special machine sprays tiny pieces of molten metal onto the crankshaft, building up the surface. Once it is sufficiently built up the area is turned back down in a lathe and polished so that it can be reused.
Tags: Arc Welder, MIG Welder, plasma cutter, TIG Welder, Welders, welding equipments for lease, Welding forum, welding machine
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Friday, February 3rd, 2012
MIG welding is most often used to join steel or stainless steel together. But with the properly equipped MIG, aluminum can be easily welded as well. Many MIGs use a device known as a spool gun to weld aluminum. It is a small, pistol shaped device that holds its own small spool of wire. The spool is approximately 4 inches in diameter and for aluminum use, the spool weighs in at about a pound. Welding aluminum requires the same DC+ polarity as other solid wire fillers. However, 100% pure argon is normally used. At times Helium can be added to improve the penetration. However for thin material, pure Argon is preferred. Aluminum MIG welding takes place in the spray transfer mode, which happens at a lower threshold than in Steel. Spray transfer is different from short circuit MIG. Trying to weld aluminum in short circuit mode, can make a terrible, wadded up mess. Spray transfer is smooth, quite, and the molten ball of aluminum pinches off before a “short” is ever created. It is a very hot process and fairly rapid and requires a much higher wire speed rate. One of the most overlooked details is that usually, the next size up contact needs to be used with aluminum wire. The greater swelling that aluminum exhibits, will cause the wire to seize up in the tip, if room for heat expansion is not left. There are other methods of welding aluminum with a MIG, including simply using the standard gun with a Teflon liner installed. In this type of setup, the cable has to be kept very straight and free from kinks or tight loops to feed properly. Of course a larger tip should be used as well. Also a similar device to the spool gun is used called a push-pull gun, which uses the cabinet to hold and push the wire, while a drive roller in the gun’s body “pulls” the wire to keep the wire from bird’s nesting inside the liner.
Tags: Arc Welder, MIG Welder, plasma cutter, TIG Welder, Welders, welding aluminum, welding equipments for lease, welding equipments for sale
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Wednesday, February 1st, 2012
There are two basic ways to control the amps. The first is with the foot pedal which allows infinite control of amps real time. Though this sounds ideal, it is not a very scientific or controlled way of welding if the protocol for welding a particular joint, or metal type defines a narrow range of amps in which the weld should be conducted. The 2T/4T setting allows the operator to start the weld simply by pressing a trigger or switch located on the torch and use pre-settable features such as starting amps, up slope, down slope, and ending amps to manage the weld from beginning to end. Using the 2T function, the 2T normally indicates a press and hold type of operation of the welder. While the switch is held down, it cycles the preset programming automatically. This works well for some situations that require very little thought or skill. The 4T breaks this cycle up to allow manual initiation of each stage of the arc cycle. Pressing and holding the switch usually starts the arc. Releasing the switch will increase the amps to normal welding amps at the rate selected by the upslope. Pressing once again, will cause amps to begin to decrease according to the pre-set down slope until it reaches the final current, which is used to fill the crater so it won’t crack. Then, the switch is released to terminate the arc. Though this isn’t for everyone, 2T/4T does work well for most other countries in the world. A foot pedal is seldom seen outside of most US based welding shops.
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Tuesday, January 31st, 2012
Besides pulse, one of the most important adjustable features on a welder like the Everlast PowerTig series, or the Miller Dynasty series, is the adjustability of the AC frequency, and the AC balance. Both play their part in getting the most out of a AC arc while TIG welding.
AC frequency has been covered before. However, many people fail to realize just how important this feature is, especially if they have never used an inverter with features like this before. Standard transformer welders don’t have any choice but to operate on the same frequency that is supplied to the welding machine through its primary transformer. In the US, that is 60 hertz. Though that is adequate for many welds made in aluminum, it is far from ideal. A more ideal setting would be twice that at 120Hz. This level focuses the arc cone, and improves arc stability. Inverters excel in this because the frequency is generated by electronic components rather than the input power line.
AC balance gives a choice between penetration, and cleaning. Older transformer TIG welders have pretty much the input power line balance of 50/50 ratio between Electrode Negative and Electrode Positive. This offers typically more “cleaning” than is required to break up the oxide layer on aluminum. And it also overheats the tungsten, creating a molten ball on the tip of the tungsten, destabilizing the arc. A sharp tip can be maintained while increasing the penetration of the welder with just a 20-30 percent setting of Electrode Positive. Again, inverters open up the possibilities here by offering adjustable balances. Even when times call for it, inverters like the Everlast PowerTig series can operate at nearly 90% or more of full electrode positive, creating huge amounts of cleaning. Though that is unusual, and a little harsh to weld with, it is nice to know you have that adjustability at your finger tips.
Tags: Arc Welder, MIG Welder, plasma cutter, TIG Welder, tungsten, Welders, Welding forum, Welding lease, welding machine
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Monday, January 30th, 2012
Pulse is more than just a setting you make or switch you flip on the machine. Though some “simple” machines may only have an adjustment for pulse frequency, there are other components to the pulse cycle that can be made with most welders. The appropriate terminology for pulse settings is not clearly standardized. This is mainly because of gaps in welding terminology and difficult terminology used by electronic engineers to technically describe what s happening. It is also because of differences in function between brands of each feature Pulse Amps, or Peak Current is used to establish a “high” current setting on some welders. On welders that use a ratio, or percent scale, this is actually a “dip” in current and is sometimes referred to as background current, or even base amps. In a welder that uses a fixed amps setting you will typically see base amps/ current, and Peak amps/ current used. In ratio controlled pulses where percentage of another current is used, this will often be listed as Main welding amps/Peak amps, and Pulse Amps/ base amps/ background current.
Next you will typically see a setting for Pulse width, Pulse Balance or Pulse time on. This is sometimes referred to as pulse duty cycle, but is often avoided because of the confusing terms involved with actual welder operation times referred to as duty cycle. The length of each stage of the pulse cycle is controlled by setting this function. It means that you can make the high amp stage of the pulse cycle longer or shorter than the low amps stage of the pulse cycle. Each half cycle doesn’t have to be balanced…it can be skewed to achieve the best result between melting and freezing. Even though the pulse is happening several times a second, each half phase of the pulse can be metered to give optimum results.
Tags: Arc Welder, MIG Welder, plasma cutter, TIG Welder, Welders, Welding forum, Welding lease, welding machine
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Friday, January 27th, 2012
A lot of experienced TIG veterans weld all their life and never get to experience TIG welder with a pulse feature. The ones that are fortunate enough to try a TIG, say an inverter TIG like an Everlast PowerTIG, with Pulse, wonder how they could have done it so long without it. Pulse offers improved heat control over the weld, without sacrificing penetration, or speed. It is particularly useful in welding thin metals or edges of seams where the heat may wick over into the shoulder of the metal destroying the edge of a joint. It can also be used to create that stack of dimes look that all welders dream of, by allowing the operator to time the “dips” of the filler metal, according to the rate of the pulse. A slow rate of pulse can make a novice look like a pro in short order because of the dips will make an evenly spaced bead.
Most simply defined, pulse is a rapid oscillation between two pre-selected amp levels, one consisting of a high amp value and one consisting of a lower amp value. The high amp values represent a “penetrating” phase of the pulse, and the low amp value represents a cooling stage of the pulse, in which little or no melting of the parent metal occurs. The high amp portion of the pulse is when the filler rod should be added. The low amp portion of the pulse is the portion of the pulse when the torch should be moved forward. One complete cycle between high and low amp level in one second is one Hertz, or one pulse per second (pps). The frequency of most of these units is adjustable. The adjustability of the pulse frequency is important as well in the width of the arc cone. The faster the pulse the more narrow and constricted the arc becomes allow it to be pointed into tight corners.
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Friday, January 20th, 2012
If you have ever struggled with arc stability while TIG welding, particularly in the lower range of amps that are suitable for the size tungsten, it likely can be attributed to improper grinding. Knowing how much point, and direction of grinding is key. In general, for all DC welding a sharp point is a good choice with a taper at least 2.5 times longer than the Tungsten is wide at lower amps. The same proportion should be used for higher amp range as well. However, to prevent issues with thorium spikes (with thoriated tungsten), and to reduce the risk of contaminating the weld, the point should by slightly snubbed, truncating the end, ever so slightly. This is good advice for DC welding with either an inverter or a transformer welder. However, for AC, the pure, green tipped tungsten that is used in a transformer will not usually be used sharp. Instead it will be balled from a flat tip, or a slightly ground tip. For an inverter, the same tungsten type and grinding can be used for AC as for DC, because of the capability to adjust the AC balance to a point that does not heat the tungsten to a molten ball. In these cases pure (green) tungsten will not be used. Whether it’s a transformer welder or an inverter, it is always critical to grind the point on a dedicated grinding wheel only used to dress the points on Tungsten to prevent contamination of the point. While grinding the tip should be ground along the length, and not radially. The fine striations that are made if radially ground around the circumference can create points of arc instability, making the arc hunt around the surface of the point.
Tags: Arc Welder, MIG Welder, plasma cutter, TIG Welder, Tungsten electrodes, Welders, Welding forum, Welding lease, welding machine
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Wednesday, January 18th, 2012
Even though people have used fixed shade helmets forever, the market is swiftly moving towards auto darkening helmets. Prices and performance both are improving. Today, auto-darkening helmets can be bought as low as 39.00 dollars. While not top of the line, they will typically be fairly good performers for average welding. Even name brand, high end companies are offering welding helmets under the 200 dollar mark.
A fixed shade helmet will never be replaced completely. It will probably always be the choice of pipeliners due to the designs available that make their use in the field irreplaceable. But in reality most other jobs can be performed with almost any good quality auto-darkening helmet. For TIG welding, however, more money may need to be spent to obtain the best performance, especially for low amp TIG. These helmets usually have 3 or 4 sensors to pick up the welding arc at different angles. But a few good quality 2 sensors do a fairly good job with TIG in all but the lowest amp ranges.
An important issue for many welders is to decide on the type of auto darkening helmet. There are principally two types: “Solar Powered” and “Battery Powered”. The Solar powered type are a little slower in switching. Some so-called Solar powered units still retain, a permanent, non replaceable battery. These will last for some time, but usually have a service life of 5 years or less. The best are the replaceable battery type which offer easy access to a commonly available battery. Some auto darkening helmets use a triple “A” battery. These are great and easy to replace in a moments notice as the batteries are only a convenience store away.
Fixed shade Auto-darks only offer a shade of 3 or 4 while not activated, and another shade of usually 10 or 11. Other, more advanced helmets offer features such as sensitivity, shade and delay selection. These are usually the best as they allow the most flexibility to fit any work environment.
When selecting between the different helmets, it comes down to budget, and overall comfort. A helmet with a lot of features could be bulky and heavy. A simple, inexpensive helmet may in fact feel better. Try several out before settling on one. Fitting and balance are important whether its fixed or auto darkening.
Tags: Arc Welder, MIG Welder, plasma cutter, TIG Welder, Welders, welding equipments for lease, Welding forum, welding helmets, welding machine
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