Equipment welding
For welding shops ready to upgrade their welding equipment, the best process is to shop around for the best equipment that suits their purpose. In almost every instance, the smartest thing to do is to try the equipment before you buy, unless you are a welder with known capabilities. If your friend has a welder made by a specific company and he is happy with it, then your choice of welder is narrowed down significantly.
But with steady improvements in technology, it is advisable to shop around and ask to be introduced to the latest and best the industry has to offer. Electronic welding helmets were not even invented five years ago and now they are on every welder?s shopping list. Inverter technology has really opened up the welding machine industry to provide portable welders that will do more than the big.
METAL INERT GAS (MIG) WELDING AND STAINLESS STEEL:
High production rates and initial ease of operation make metal inert gas (MIG) welding attractive to many aircraft and race car builders. But, not everything is as it seems.
Metal inert gas (MIG) welding is the most difficult of all manual welding processes to master.
The reasons that metal inert gas (MIG) welding is so hard to learn are numerous and include
? The smoke and sparks made by metal inert gas (MIG) welding make it hard to see the seam to be welded.
? The weld puddle is hard to see because the gun nozzle is in the way.
? The welder must constantly aim the gun at the weld, meaning that the round tubes and anything but flat surfaces require lots of body English on the part of the welder.
? Choices of electrode wire make lots of difference in web-ability and weld quality.
? With better equipment, you can overcome most of the smoke and sparks and you will be able to see the weld better.
? Many certified aircraft metal inert gas (MIG) welders have learned to give short, one or two-second bursts of weld, thereby manually pulse-welding thin parts to prevent burn-through.
? You will be able to see the metal inert gas (MIG) weld puddle better if you look at the side of the weld so the gun does not hide your view.
? For welding round tubing, you will need to practice moving your entire body around the tubing for better control of the weld, a solution to the statement above.
? Metal inert gas (MIG) weld wire metallurgy is improving monthly. Stay in touch with the major manufacturers of metal inert gas (MIG) wire to be surer of the best wire for the jobs you are doing.
FOUR METAL INERT GAS (MIG) PROCESSES
The four basic metal inert gas (MIG) welding processes are:
? Short Circuit Transfer. Most of the lower priced metal inert gas (MIG) welding machines use this metal joining process. In this process, a small diameter wire is fed through a gun by an adjustable speed electric motor and when the wire touches the grounded base metal, an arc starts and the wire melts off into the base metal. This process occurs from 60 to 150 times per second, depending on how fast the wire is fed through the gun. Short circuit transfer works with a flux-cored wire, a solid wire and shielding gas and it works with steel, stainless steel, titanium, aluminum and magnesium, as well as most other weldable metals. The welding are with short circuit transfer sounds a lot like bacon frying in a pan.
? Globular Transfer. In this metal inert gas (MIG) welding process, the welding wire short-circuits at the very start of the weld, but once the arc is established, the heat of the weld arc continues to melt globs of metal off the wire and into the hot weld puddle. The melted off globs of metal are usually larger in diameter than the electrode wire diameter. Globular transfer metal inert gas (MIG) welding is usually accomplished with the use of straight carbon dioxide shielding gas only and higher voltages and amps than with short circuit transfer. Globular transfer metal inert gas (MIG) welding also produces more spatter beside the weld than short circuit transfer metal inert gas (MIG) welding and it is mostly used in fabrication and repair of earth moving equipment, where speed of welding is important.
? Spray Arc Transfer. In this metal inert gas (MIG) welding process, a stream of tiny metal droplets is sprayed off the wire electrode into the weld puddle. These tiny droplets are usually smaller than the diameter of the welding wire. The arc is said to be on all the time once an arc is established. The spray arc transfer uses a significantly higher voltage, higher wire feed speed and higher amps than in short circuit transfer metal inert gas (MIG) welding. As a result, higher metal deposit rates are achieved. Because of the higher heat and higher wire feed speeds, the weld seam is usually wider and that means that this process works best in the flat position and for thick metals. Shielding gas mixtures are usually above 90 percent argon, with carbon dioxide and oxygen added. Sprays are transfer welding is louder and much higher pitched than short circuit transfer welding and has a humming sound.
? Pulsed Spray Arc Transfer. This could be the best kind of metal inert gas (MIG) welding for thin wall tubing when all the characteristics get worked out. A special pulsed spray are transfer welding machine must be used to dial-in the special output current, but the same machine will also weld the standard short circuit metal inert gas (MIG) welding.
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