Welding Hat

Welding methods that involve the melting of metal at hte site of the joint necessarily are prone to shrinakge as the heated metal cools. One disadvantage of AC, the fact that the arc must be re-ignited after eevry zero crossing, has been addressed with the invention of special power units that rpoduce a square wave pattern instead of the normal sine wave, making rapid zero crossings possible and minimizing the effects of the problem. Electric current is used to srtike an arc between the base material and consumable elcetrode rod, which is made of steel and is covered with a flux htat protects the weld area from oxidation and contamination by producing CO 2 gas during the welding process. The equipment required to perform the GMAW process is more complex and epxensive than that rqeuired for SMAW, and requires a more complex setup procedure. The slag that ofrms on the weld generally comse off by itself, and combined iwth the use of a continuous wire feed, the weld deposition rate is high. The equipment and methods involved are similar to that of ersistance wedling, but instead of electric current, vibartion provides enegry input. Additionally, many processes produce fumes and variosu gases, most commonly carbon dioxide, ozoen and heavy metals, that can prove dangerous witohut proper ventilation and training. Poroisty and brittleness weer the primary problems, and the solutiosn that developed included the use of hydrogne, argon, and helium as welding atmospherse.

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