Electrodes For Tig Welder
The electrodes, having to be of a material capable of withstanding temperatures of the electric arc, are, for many years only tungsten or its alloys, the beginnings of this technology (the forties) were also used graphite electrodes. Tungsten, as well as having the best mechanical thermal characteristics, is preferred for its high thermoelectric power (ability to emit electrons at high temperature), which stabilizes the arc.
To increase the thermoelectric power of W, the electrodes are sometimes associated with small percentages (1-2%) of Th (electrodes toriati). The electrodes can be found in business in various diameters from 0.25 to 6.4 mm. They are generally used in direct current (DC), polarity direct (PD), ie with the positive pole on the piece. The use of reverse polarity (pi), ie with the negative pole on the piece, is used for welder of light metals (Al and Mg) or when it is important to the stability of the arc.
However, since the ccpi provides less energy to the bathroom, and requires higher arc currents, it is often better to replace it by welder in alternating current (AC), which can be symmetrical or asymmetrical. The electrode before being used in CCPD, must be sharp because the point we assume a conical shape with a height of about 1.5 times the cone diameter, this will increase its ability to emit electrons, and then get a good warm bath with the current relatively low. But in ccpi we must try to take the electrode a flat (and, of course, for these uses, you avoid using electrodes toriati), just to limit the emission of electrons, which would require a higher voltage for the same stream ‘arc.
