Arc Welding Equipment
Arc Welding Equipment : Cables
Two welding cables of sufficient current carrying capacity with heavy, tough, resilient rubber jackets are required. One of the cables should be composed of fine copper strands to permit as much flexibility as the size of the cable will allow. One end of the less flexible cable is attached to the ground lug or positive side of the direct current welding machine; the other end to the work table or other suitable ground. One end of the flexible cable is attached to the electrode holder and the other end to the negative side of a direct current welding machine for straight polarity. Most machines are equipped with a polarity switch which is used to change the polarity without interchanging the welding cables at the terminals of the machine. For those machines not equipped with polarity switches, for reverse polarity, the cables are reversed at the machine.
An electrode holder is an insulated clamping device for holding the electrode during the welding operation. The design of the holder depends on the welding process for which it is used, as explained below.
Metal-arc electrode holder
This is an insulated clamp in which a metal electrode can be held at any desired angle. The jaws can be opened by means of a lever held in place by a spring (fig. 5-25).
Atomic hydrogen torch
This electrode holder or torch consists of two tubes in an insulated handle, through which both hydrogen gas and electric current flow. The hydrogen is supplied to a tube in the rear of the handle from which it is led into the two current carrying tubes by means of a manifold. One of the two electrode holders is movable, and the gap between this and the other holder is adjusted by means of a trigger on the handle (fig. 5-26).
Carbon-arc electrode holder
This holder is manufactured in three specific types. One type holds two electrodes and is similar in design to the atomic hydrogen torch, but has no gas tubes; a second equipped with a heat shield; the third type is watercooled.
Arc Welding Equipment : Accessories
Chipping hammer and wire brush
A chipping hammer is required to loosen scale, oxides and slag. A wire brush is used to clean each weld bead before further welding.
Figure 5-27 shows a chipping hammer with an attachable wire brush.
Arc Welding Equipment : Welding table
A welding table should be of all-steel construction. A container for electrodes with an insulated hook to hold the electrode holder when not in use should be provided. A typical design for a welding table is shown in figure 5-28.
Arc Welding Equipment : Clamps and backup bars
Workpieces for welding should be clamped in position with C-clamps or other clamp brackets. Blocks, strips, or bars of copper or cast iron should be available for use as backup bars in welding light sheet aluminum and in making certain types of joints. Carbon blocks, fire clay, or other fire-resistant material should also be available. These materials are used to form molds which hold molten metal within given limits when building up sections. A mixture of water, glass, and fire clay or carbon powder can be used for making molds.
Arc Welding Equipment : Goggles
Goggles with green lenses shaped to cover the eye orbit should be available to provide glare protection for personnel in and around the vicinity of welding and cutting operations (other than the welder).
NOTE: These goggles should not be used in actual welding operations.