by Curtis Von Fange
One of the most useful skills that an owner of older equipment can have
is the knowledge and ability to weld. It seems like the older
equipment can do a job, albeit slowly compared to newer stuff, but it
tends to break more often. Many of the breakdowns are related to the
implements that are being used: the disc, wagon or bushog are among
them. Knowing how to fix stress cracks, reinforce weak joints by
welding on steel support plates, or cutting and shaping parts and
adapters out of raw steel plating is an asset that is worth its weight
For the farm environment there are two types of welding that we will
deal with in this series. Arc welding and oxy-acetylene. The latter
will also include some pertinent information on cutting torches and
fabrication of parts and tools. But we will first cover some basics
dealing with arc welding.
Arc welding is as the name implies, welding with an arc. Simply put, a
positively charged electrode and a negatively charged steel plate
commonly called a ground complete a circuit at the end of a welding
rod. When the rod is held a given distance from the item to be welded
the current jumps the gap creating an enormous amount of heat. The
heat melts the rod end and when the rod is manipulated in a certain
fashion a puddle of liquid metal will result which can be controlled to
make a weld. Of course it is a little more involved than the simple
description above, but the basic premise is that simple; electrical
current jumping an air gap melts the metal.
There are many types of arc welding. A few are carbon-arc,
metal-electrode, gas metal-arc, atomic-hydrogen, MIG, TIG, and many
others. For our purposes we will focus on two basic types of arc
welding; AC and DC. It is difficult to explain the difference in
simple, down to earth terms so lets just settle for some of the main
differences and advantages of each.
AC, or alternating current, is probably the most common and most
economical of welders. A good unit can be purchased at a farm store
for quite a reasonable price. It will do many simple welding tasks
with excellent results. The distinct advantage that AC arc welding has
is that there is virtually no magnetic blow, which causes excessive
splatter and uncontrollable arcs. The basic features are a good
forceful arc, an easy arc to maintain once it is begun, it is great for
heavy steel plating because of deep penetration, and is wonderful for
welding aluminum. The negative factors are that the initial arc can be
difficult to start and that burn throughs on thinner plates of metal
can be a frustrating problem. All in all though, a simple AC welder is
a good all around tool for general repairs.
DC, or direct current, provides for a more variety in welding. Direct
current, by nature, can be manipulated in ways completely different
than the alternating cycles of AC. One example of this is that by
changing the polarity of current flow different welding characteristics
can be realized. Straight polarity, when the current flows from the
rod to the base metal, provides a fairly standard arc for a variety of
metals. Reversed polarity, when the current flows from the base metal
to the rod, provides for 2/3 of the total heat to be centralized in the
welding rod tip. This superheats the electrode metal and shielding gas
from the flux causing the molten metal to travel at a high velocity
resulting in very deep penetration to the base metal. These variations
in the types of DC units can accommodate welding on thick or thin
metals. This can give quite a bit of flexibility when trying to avoid
burn throughs with thinner base metals or working on deeper weld
penetration on thicker plates.
As with any trade there are certain hazards which must be addressed
when arc welding.
- 1. Avoiding radiation from the arc, ultraviolet and infrared rays
- 2. Flying sparks, globules of molten metal
- 3. Electrical shock
- 4. Fumes
- 5. Burns
Protective clothing and specialized eye protection must be used in
order to reduce these risks. An arc-welding helmet with protective
lens reduces the amount of harmful eye radiation and protects the head
from splatter and heat. The hair, hands, arms and other skin surfaces
must be covered, preferably with heavy leather to shield out other
harmful radiation produced by the intense arc. Don't wear regular
coverings like heavy cotton or wool as arc welding is accompanied by
flying sparks and molten metal pieces that will ignite such clothing.
Also avoid pants with cuffs, tennis shoes, thin gloves, and shoes with
Avoid electrical shock by working on a dry floor with thick rubber
shoes and by wearing dry leather welding gloves. Also make sure to use
insulated electrode holders and have the equipment properly grounded.
Keep the area properly ventilated to avoid inhaling the burnt fumes.
The fumes generated in the welding process may contain highly toxic
metal oxides. Keep in mind that you are welding with molten metal.
The arc is hot, the metal is hot, and everything in contact with the
metal is hot. Watch for falling metal globules; they burn quickly
through tennis shoes and unprotected pants. When done welding use
tongs to pick up the metal; it does not cool quickly and even when
quenched in water beware of the superheated steam it produces when
dipped and the heat it retains when removed.
Above all be aware of others around you. When an arc is struck to
start welding the sudden flash can cause severe eye damage to
onlookers. Continued observation will quickly cause irreversible
blindness. Keep people away from the project. Protect them as well as
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