Views:7 Author:Site Editor Publish Time: 2018-09-28 Origin:Site
The tungsten electrode used in gas tungsten arc welding (GTAW) is a consumable. It serves merely as the terminal for the electric arc which produces the heat needed to join the base metal being welded. Filler metal may sometimes be added to the weld pool, depending on base metal thickness, joint design and weld characteristics desired.
The shape of the tungsten electrode tip is an important process variable in GTA welding. Tungsten electrode geometry has an affect on the arc shape (thereby affecting the weld bead size and shape), the weld penetration, and point longevity of the electrode. The electrode’s geometry is thus a welding variablethat should be monitored during weld procedure development. In addition, proper electrode grinding
procedures and equipment should be used in order to ensure that electrodes are dimensionally correct. Finally, different tungsten materials pose different characteristics in arc start ability, electrode life, and contamination resistance. This makes the selection of the proper material for your application an important variable in welding performance. The proper preparation of your electrodes in each of these areas will provide the benefits of consistent welding with optimum performance.
This booklet is written to provide the Manufacturing Engineer a general reference for selecting the most appropriate tungsten material and emphasizes the importance of a correctly prepared, ground and cut tungsten electrode.
APPLICATIONS FOR TUNGSTEN WELDING ELECTRODES
ORBITAL TIG/TUBE WELDING
To produce the high quality orbital fusion welds required of today's high tech industries, tungsten electrode shape is an important variable that must be kept consistent. Most orbital manufacturers require a precise tungsten length.
ORBITAL TIG/PIPE WELDING
Orbital pipe welding application using TIG is primarily limited to the nuclear, pharmaceutical, and chemical processing industries. These industries, along with a few not mentioned, require X-ray perfect orbital pipe welds in the 125 amp - 300 amp current range. A consistently prepared electrode is required for consistent current flow and arc voltage characteristics. Most orbital pipe welders use 3/32 or 1/8 diameter electrodes. They also must be cut-to-length, however, not as precise as the orbital tube welder.
MECHANIZED TIG WELDING
Mechanized TIG Welding encompasses a wide spectrum of applications such as precision bellows welding using .040 diameter tungsten electrode at 1.0 ampere up to high speed tube mills welding with a 250 diameter tungsten electrode using current as high as 600 amperes. A precise yet consistent electrode will have a dramatic effect in weld results and tungsten electrode life. Cutting the tungsten electrode is usually required if the electrode is grossly contaminated.
MANUAL TIG WELDING
Arc starting and arc stability from a consistently prepared tungsten electrode will be beneficial to the manual welder. Most hand welding 'FIG torches require a 7.0" long electrode be cut in half to fit the manual welding torch. This can be accomplished best with the diamond cutting mechanism described in this booklet.
MANUAL & MECHANIZED PLASMA ARC WELDING
The plasma arc welding process requires a very precisely shaped, tungsten electrode. The tip of the tungsten must be kept concentric to the diameter to place it in the correct position centered in the plasma torch. This is a critical parameter adjustment in plasma arc welding. Most plasma welding torches also require a cut-to-length tungsten electrode.