In some rare cases there are three types of mixture used. The first is Argon and hydrogen and the second is Argon and Nitrogen. The third mixture is Argon and Helium and that is typically used on thicker metals to get deeper weld penetration. In most cases pure Argon will cover almost all welding needs. As the name states "Tungsten Inert Gas Welding" tungsten is the main ingredient in the electrode. What changes is there are very small percentages of other metals added to help create the desired arc characteristics.
The common metals added to Tungsten are Cerium, Lanthanum, and Zirconium. In the real world the following Tungsten mixtures are the most widely used:. Zirconium Tungsten has similar properties to pure Tungsten. Thoriated Tungsten is typically used with direct current and the polarity is DCEN electrode negative. The added Thorium Oxide helps the electrode carry more current at a lower temperature while making arc starting a bit easier. Thoriated Tungsten is used for welding most metals besides aluminum and magnesium.
Some of the metals it works well on are carbon steel, stainless steel, chromium alloys, nickel, and most other ferrous metals. As with all electrodes there are choices in electrode diameters. With TIG welding the electrode size is not the most critical component of the process.
As long as the electrode used stays within it amperage rating. What matters the most is the shape of the tip and that determines the arc characteristics. The more common sizes on the market are:. Since Tungsten comes in a rod form with a square cut end it needs to be shaped.
Some of the tip shapes used in these electrodes are pointed, rounded, and tapered with a ball end. A pointed tip is typically used in welding ferrous metals like steel. The current used is DCEN direct current electrode negative.
What this does is allow the current to flow from the electrode to the metal. This allows the electrode to concentrate the arc temperature onto the metal. The pointed tip in this case will keep its shape by maintaining a higher arc temperature then the electrodes melting point.
If the polarity were reversed the tungsten would likely start melting. Shaping of a pointed electrode is typically done on a grinding wheel or Tungsten electrode sharpener.
When using a grinding wheel it is best to use a fine grit wheel that is only to be used for sharpening Tungsten electrodes. There is a downside to using a grinding wheel.
Since Tungsten is slightly radioactive you really do not want to inhale any of the particles! To sharpen the electrode point it upward while slowly and lightly rolling it on the grinding wheel between your fingers to obtain a round point. Oh yeah, don't wear gloves while doing this! The last thing you need is a glove to be pulled into the grinding wheel! If you can afford it then there are tungsten sharpeners that work just like a pencil sharpener. They are much safer and produce a perfect point every time.
All you do is put your tungsten in and it does everything else. Rounded or tapered ball end electrodes typically used for welding non-ferrous metals like aluminum and magnesium. The rounded or tapered ball ended electrode helps by spreading the arc over a wider area of the electrode. To get a round or ball shaped end to an electrode, this it is done using DCEP direct current electrode positive. To get this shape the Argon gas should be turned on and if possible start an arc on a piece of copper.
What will happen is the tungsten will begin to melt once the amperage is high enough and then start to create a droplet at the end of the electrode. Once you get the proper size ball at the end of the electrode, stop the arc. In the case a piece of copper is not available simple use the cleanest piece of metal you can find to the job. In some other cases a rounded or tapered ball end electrodes can be used for welding sheet metals with DCEP direct current electrode positive.
Otherwise the tungsten will burn up! Cup sizes come with a standard coding system. The coding system is pretty simple! Whatever numbers used on the cup size always assume it the first number of an inch broken down into 16'ths of an inch. Just like any other welding process the filler wire for TIG welding has a designation coding system.
Since TIG welding does not use any flux, the designations are pretty simple. In most cases you can use MIG welding wire. Typically TIG welding wire comes in 36" lengths. A common welding wire for mild steel is ER70S The designation code is as follows:.
TIG welding Electrode wire also has the designation and size stamped on the wire itself. One wrong electrode and you can ruin a weeks worth of welding. Getting caught on a high end job without the wire designation on your electrode will get you fired. Joint set-up is extremely critical when it comes to TIG welding.
There cannot be any rust, oxidation, mill scale, paint, oil, or anything that does not belong there except for the bare metal. All joints must be cleaned with a grinder or in the case of some metals like aluminum a chemical cleaner is used.
One of my first jobs was welding aluminum in a factory and every piece to be welded got an acid bath before welding. TIG welding in my opinion produces the best weld quality but that weld quality depends a lot on a clean joint. Purging is a common term when it comes to TIG welding pipe.
What purging does is replace the air in a pipe with a gas that will not react with the root of the weld. Purging prevents weld oxidation or in pipe welder slag "sugar".
When interviewing for pipe TIG welding jobs a common question asked is "How do you prevent sugar"? In other cases when welding a box can be filled with Argon to weld in it. Argon is heavier than air so it will fill a box or shape just like water. Argon can also be dangerous when the proper ventilation is not used. If you are in a sealed room and you have a bottle of Argon leaking, it will fill the room from bottom up, just like water would.
Unlike water you cannot see or smell it. Once the Argon fills the room you will be breathing and suffocating at the same time, while not even knowing it!
Typically Argon is used to TIG weld but since it is very expensive it is not used by itself to purge pipe. What most people use to purge a pipe is Nitrogen or Co2 gas. Purging pipe typically requires the use of math. Fluke Welder Manuals. Garmin Welder Manuals. GE Welder Manuals. Genie Welder Manuals. Graco Welder Manuals.
Grizzly Welder Manuals. Haier Welder Manuals. Harbor Freight Tools Welder Manuals. Hitachi Welder Manuals. Hobart Welder Manuals. Hobart Welding Products Welder Manuals. Honeywell Welder Manuals. Auto-Crater allows time for addition of filler to crater, and eliminates unwanted arc strikes outside the weld area for better weld finishes.
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