802 Agricultural Mechanics and Technology Systems
Copyright Goodheart-Willcox Co., Inc.
produced by beginning welders. Many varieties and qualities of fi lter lenses
are available. They may be made of plastic or glass, refl ective or nonrefl ective.
Auto-darkening lenses are triggered to darken by the welding fl ash.
A sensor detects bright light and causes a liquid crystal display (LCD) to
polarize and distort the light to limit the amount of light passing through
the lens. These lenses are popular with many welders and greatly improve
visibility when a weld is begun. However, welding for extended periods of
time warrants the use of lenses that offer more protection to reduce eye fatigue.
OSHA-approved (Z87.1) goggles or glasses must be worn at all times,
including under the welding helmet. As welded beads cool, particles of hot
slag often pop off and are propelled some distance due to the forces created
by the contracting steel and slag. When the welding helmet is raised, eye
protection must already be in place.
Gauntlet-type, heavily insulated leather welding
gloves protect the hands from the heat and radiant
energy of the welding arc. See Figure 29-45. Covered
leather shoes protect the feet and ankles from burns
and injury from sharp or heavy objects. Synthetic soles
with prominent tread are more resistant to slipping and
provide some protection from electric shock.
Heavy cotton, long-sleeve shirts and pants
are resistant to burning and protect the body from
ultraviolet and infrared rays. Shirts should have
covered pockets or no pockets, since open pockets can
catch hot metal spatter. Pants should not have rolled or
frayed cuffs. Do not wear clothing made of synthetic,
petroleum-based fi bers such as rayon or nylon while
using a torch. Fire-retardant clothing is available
for workers facing high levels of exposure. Leather
aprons, leather sleeves, welding chaps, or a welding jacket may be necessary,
especially when performing operations that require out-of-position welding.
Practice Welding
The formation of strong, uniform beads is the goal of every welder.
Practice is required to attain the skill needed to correctly strike the arc and
weld uniform beads.
Striking an Arc
A successful welder is able to strike an arc and maintain it without
having to think about the process. The most common ways of starting an arc
are by tapping the electrode to the grounded base metal or by scratching the
electrode, like a match, across the steel.
Scratching is the easiest way to begin. Sweep the tip of the electrode
against the metal as if striking a match. Once the electrode makes contact
with the steel, the arc starts. The tricky part is to locate where the weld
should begin and move the arc quickly to that spot. It takes practice to be
moomsabuy/Shutterstock.com
Figure 29-45. Gauntlet-type gloves for SMAW
are made of insulated thick leather to provide
protection from the intense heat of the welding arc.