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The electrode extended from the end of the contact tip to thearc is properly known as electrode extension.
For short-circuiting metal transfer or GMAW-S, semiautomaticwelding, the electrode extension should be held between3/8-1/2 (10 12 mm). For either axial spray or GMAW-P,pulsed spray metal transfer, the electrode extension should beheld between 3/4 1 (19 25 mm). Maintaining the correctelectrode extension is important to the uniformity of thepenetration profile along the length of a weld, and it is consideredto be an important variable for any GMAW procedure.AWS specifies winding requirements for GMAW solidwire electrodes. Cast and helix are two key requirements.Figure 31 shows a graphic depiction of cast and helix in aGMAW wire electrode. To measure cast and helix, a sample ofwire electrode should be taken from the spool large enough toform a loop when it is cut from the package, and then left unrestrainedon the floor. Cast is essentially the diameter of the loop(if the shape is an oval, it is the largest diameter circle that will fitwithin the oval). AWS requires the cast to be not less than 15for 0.035 (0.9 mm) and larger diameter electrodes and not lessthan 12 for 0.030 (0.8 mm) and smaller diameters on all spoolpackaging larger than a 4 spool, [1 lb. and 2 lb. (0.5 and 0.9 kg)spools]. Helix is the rise of the wire electrode off of a flat surface.AWS specifies that the helix be less than 1 (25 mm) atany location.