4–1. Tables are also available for aluminum conductors.
Table 4–1 Copper welding lead sizing
Work-Lead Connections
What are the common designs of work-lead connections?
•Spring-loaded
•Screw-clamp
•Magnetic attachment
•Tack welded connectors
See Figure 4–25.
Figure 4–25Work-lead connection methods include: spring-loaded, screw-type, magnet type, and tack-welded connections
Why is it important to have a good work-lead connection?
A poor work-lead connection will generate heat between the connection and the work. It is best to make a solid connection on freshly cleaned base metal. Use a grinder or wire wheel to get through rust, paint, and mill scale. If the welding electrode holder overheats, this is an indication of a poor work-lead connection.
Welding Hand Tools
What hand tools is the welder likely to need?
•Chipping hammer to remove welding slag
•Wire brush for cleaning welds
•Hammer and cold chisel to break tack welds
•Pliers for moving hot metal safely
•Wire cutters to trim electrode wire (GMAW and FCAW only)
See Figure 4–26.
Figure 4–26Various hand tools
Safety Equipment
•Welding helmet with the proper lens shade for the process and amperage.
•Leather capes and sleeves or jacket called skins or leathers, to protect the welder’s clothing from sparks, especially while welding overhead.
•Welder’s cap to protect from sparks getting behind the welding helmet and into the welder’s hair. See Figure 4–27.
Figure 4–27Welding safety equipment
•Breathing apparatus to provide the welder with fresh air in confined spaces with inadequate ventilation. Safety glasses under the welding helmet.
What is and what are the advantages of the electronic faceplates?
•An electronic faceplate or lens is one of the most recent and important safety devices developed in the welding industry. These devices are designed to be clear, or nearly clear, then darken the instant arc is established; when purchasing be aware of the time the lens takes to darken 1/25,000 of a second or faster is recommended.
•The welder does not need to raise and lower his helmet when performing a series of welds: he can always see where he is with the helmet down.
•The beginner does not have to master holding his electrode steady when he drops his helmet. This permits beginners to perform better welds earlier in their training.
•Electronic faceplates offer continuous eye protection from infrared radiation coming off red-hot metal even when they are not in the darkened mode. It is just easier on the eyes and the welder is less likely to incur eye injury from inadvertent arc strikes.
Safety
What is the authoritative source of welding safety information?
Consult the AWS (American Welding Society) booklet Safety in Welding Cutting and Allied Processes, Z49.1.
What safety issues must we remember with SMAW, GMAW, FCAW, and GTAW?
•Protection of face and eyes from sparks and radiation with a helmet and lens of appropriate shade number (darkness).
•Protection of all of the welders skin from arc and weld material radiation by covering it with cotton, wool, specially treated canvas jackets or leather garments; ultra violet radiation is carcinogenic.
•Personnel in the welding area must be protected from the welding arc and sparks by protective screens. Never view the welding being performed through the protective screens alone; the only way to safely view welding is through the proper shade lens and welding helmet or goggles.
•Beware of hazards from gases and insure adequate ventilation; inert shielding gases may cause suffocation in confined areas.
•Provide adequate ventilation from welding process smoke and the metal vapors, particularly heavy metals like zinc and cadmium that are toxic; keep your head out of the welding plume.
•Leathers or specially treated canvas jackets must be worn when welding vertically or overhead to protect the welder from the falling hot metal, sparks and slag.
•A welder’s hat will prevent both radiation burns to the head and hot sparks, falling slag and hot metal burns.
•High-top boots can prevent hot sparks and slag from burning your feet.
•Never weld with pant cuffs sparks falling into cuffs will burn pants.
•Make sure your welding gloves are dry and have no holes.
•Keep hands and body insulated from both the work and the metal electrode holder.
•Do not change the polarity switch position while the machine is under welding current load.
•Welding machines must be turned off when not attended.
•Must not stand on a wet surface when welding to prevent electric shock.
•Welding cables and electrode holders must be inspected for broken insulation regularly to prevent electric shock.
•Welding power supplies on AC lines must be properly grounded and emergency shut-off switch location known and accessible.
•Welding area must be dry and free of flammable materials.
•Protect your ears from welding and grinding noise with ear plugs or ear protectors.
•Any compressed gas cylinders
