Therefore, e. In many instances, it is also possible to increase the welding speed. The shielding gas flow setting depends on the gas nozzle diameter and the surrounding air flow. Higher flow rates are required in draughty rooms Fig.
All shielding gases for arc welding and cutting are standardised in this standard. The shielding gases are divided into seven groups and additional subgroups. In addition to argon and helium, the gases in Group R1 are used for TIG welding and plasma welding, while gases in subgroup 2, which have a higher hydrogen content H are used for plasma cutting and backing forming gases. Group I combines the inert gases. There are 3 or 4 subgroups in each group.
The gases are classified from M1. The main component of these gases is argon. Oxygen O or carbon dioxide CO2 or oxygen and carbon dioxide three-component gases are mixed with active components. Helium, like pure Argon, is generally used with non-ferrous metals, but also with stainless steels. Because it produces a wide, deep penetration profile, Helium works well with thick materials, and is usually used in ratios between 25 — 75 percent Helium to 75 — 25 percent Argon.
Adjusting these ratios will change the penetration, bead profile and travel speed. However, it is more expensive and requires a higher flow rate than Argon. With stainless steels, Helium is typically used in a tri-mix formula of Argon and CO2. The MIG gun consumables diffuser, contact tip and nozzle play a crucial role in ensuring that the weld pool is properly protected. If you choose a nozzle that is too narrow or if the diffuser becomes clogged with spatter, for example, there might be too little shielding gas getting to the weld pool.
Likewise, a poorly designed diffuser might not channel the shielding gas properly, resulting in turbulent, unbalanced gas flow. Both scenarios can allow pockets of air into the shielding gas and lead to excessive spatter, porosity and weld contamination.
When selecting MIG gun consumables , choose ones that resist spatter build up and provide a wide enough nozzle bore for adequate shielding gas coverage. Some companies offer nozzles with a built in spatter guard that also adds a second phase of shielding gas diffusion. This results in even smoother, more consistent shielding gas flow. Using the guidelines above should provide a good start to the learning process.
Be sure to consult your local welding supply distributor prior to making a final decision. The little details are big deals in welding. Subscribe to our blog via the form to the right. Apply Now Request Info. Info for Parents. Out of State Students. Adult Students. Military Students. Fill out the form to recieve a no obligation info packet. Email Address. Phone Number. Zip Code. Get Started. Argon Argon accounts for 1 percent of air and is a by-product of the air-reduction processes used to produce oxygen.
Helium Helium is effective for mechanized applications but less forgiving for manual welding. Hydrogen Hydrogen is often used in combination with other gases.
Nitrogen Nitrogen increases weld penetration and arc stability. Oxygen Similar to hydrogen, oxygen is usually used with other gases to shield the weld. Carbon Dioxide Carbon dioxide is best suited for steel and is especially useful in metal inert gas MIG welding because it increases weld speed, penetration and mechanical properties. You Might Also Like Stay Updated!
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