When you first start TIG welding with copper for your metal fabrication projects, you may be given some misinformation that could ruin your finished results or put you at risk for serious injury. Below are four misconceptions and the truth about what you really need to be doing.
Having Helium Or A Helium-Argon Mixture As Your Shielding Gas
Some fabricators may argue that having helium or a helium-argon mixture works best as your shielding gas. However, helium is not ideal for two reasons. First, it burns at higher temperature than is needed for use with copper. It could warp the metal and overheat your tungsten electrode.
Second, although helium is a gas, it is denser than the air. When used as a shielding gas, it gathers at the welding spot and contaminates the weld. This will cause gas bubbles in the finished project, giving you a weaker weld that could crack or break under pressure.
Instead of using helium, use argon as your shielding gas. It is much lighter than helium, decreasing the chance of gas contamination of the weld. It also burns at a temperature that melts the copper without damaging your equipment.
Sharpening Your Tungsten Electrode Into A Radial Ground Tip
Some welders believe you should grind the tip of the tungsten electrode into a radial ground tip when welding copper. The premise behind this misconception may seem sound, since it may seem logical that a sharper tip will give you better control over the pulse. However, the tiny point creates an arch wander wave that is difficult to predict and control.
When working with copper, use a straight ground tip. The flattened tip gives you a more stable arc, giving you precise control over the pulse.
Cooling Off Your Copper Using Water
Because copper is a rapid conductor of heat and electricity, the metal becomes hot soon after you start welding it. One trick some welders use is to submerge the non-weld points in cold water to rapidly cool it. However, doing this could not only ruin the weld but could be dangerous.
Whenever you are welding any type of metal, it must be dry to keep water molecules from contaminating and weakening the weld. Although your work area is not submerged in water, it is still exposed to droplets and condensation.
Submerging copper in water while you are welding it is also extremely dangerous. Both the metal and water are conductors. When combined together with the welding pulse, the combination could cancel out your ground, increasing your chances of electrocution.
To keep the metal cool while you are working, lay it down on a steel table. The steel will disperse the heat and draw it away from the copper. Place a fan to blow underneath the table to circulate the air and further cool the metal.
Even with using the above suggestion, you need to take a three minute break from welding every four feet. This gives the copper time to cool off enough to keep from overheating and warping.
Using Straight Copper Wire As Your Filler Metal
Although it may seem like a good idea to use straight copper wire as your filler metal, the wire does not bond as well as you may think. Copper tends to be flimsy, especially when you are working with thin sheets of the metal. When cutting or joining copper sheet, you need a stronger metal to hold the pieces together.
Instead of using straight copper wire, ERNiCrMo-3 is the recommended filler metal for use with copper. While copper is its primarily element, it contains enough aluminum and nickel alloy to give it a higher tensile strength, resulting in a stronger bond with your copper sheet metal.
Once you know what to do and practice a few times, your copper TIG welding projects should work out better. However, if you have further questions, you may want to find a senior member in your company's metal shop who is experienced with all forms of welding and metal fabrication so they can show you the proper way to work with copper.Share