Welding Basics, Part 2|
by Curtis Von Fange
Part One of this series can be found here
Welding, Settings and Electrode Types
We are still dealing with arc welding on our broken bushog in this
series. Our welder of choice for this project will be an AC arc welder
since it seems to be relatively common on farm sites and will also give
us the heat we need for a good penetrating weld. We've also amassed
our protective gear and decided on our location for work. The
onlookers have been chased away for their own protection. So what else
do we need to know before we start welding?
I suppose we should probably take a look at the electrodes, or welding
rods, and see what they are all about. The welding rod is where the
action takes place. This is where the heat is concentrated, the puddle
of metal is manipulated, and the repairing weld is created.
Professional welders consider many factors when picking out a rod for a
job. The types of material being welded play a large part in this
choosing process. Is the metal a mild, low alloy, or nickel steel?
Does it have other melted components like chromium, manganese, or
vanadium in it? Is it aluminum, copper mix bronze or lead? There are
almost too many types of metals to choose from, each using a different
rod to ensure proper metal bonding. So for our bushog repair we'll
just settle for a mild steel type of rod.
Next we have to have a basic understanding of what all those gazillion
numbers imprinted on the rod mean. Most rods that one runs across at
the farm supply store will be labeled something like this: E 6011
or, perhaps, E 7020. The 'E' means that it is an electrode suitable
for arc welding. The following two numbers indicate the tensile
strength of the material in the rod when the weld is stress relieved.
'60' stands for 60,000 psi, '70' for 70,000 psi, etc. The next number,
a one, two, or three, indicate the position of the joint the electrode
is designed to weld. For example, an electrode numbered XX1X will weld
in all positions. A XX2X will weld butt and fillet joints in the flat
or horizontal position. XX3X is recommended for flat position welds
only. The last number is an indicator of the power supply, type of
covering, type of arc penetration and presence of iron powder. Once
again, since thoroughly understanding all these numbers, metal types,
and flux compounds won't get our bushog repaired we'll simply settle
for some general guidelines.
- 1. A 60XX rod will be easy to find at our supplier and will work great
for our mild steel application.
- 2. Since cracks rarely stick to flat surfaces we will opt for a
multipositioning rod, XX1X
- 3. The fourth number, XXX1 will provide us with an arc stabilizer
which will give us AC capabilities.
4. Our rod selection should be E 6011 for our bushog repair.
Now that we've selected our welder, our safety equipment, and rod lets
get an idea of the current level to use. The thickness of the metal to
be welded and the diameter of the corresponding rod will pretty much
determine the amperage setting. Pick out a rod that is about the same
size as the metal. An 1/8 inch rod will have a setting between 30 and
80 amps. The higher the setting the more heat generated; consequently,
the weld will have to be faster or the metal will burn out; there may
also be more splatter to contend with. The lower the setting the more
sluggish the arc will be, there will be poorer weld penetration, and
the arc may flame out more often. Experimenting on a piece of scrap
metal will help determine the setting you are most comfortable with.
If you are using a 3/16 inch rod the settings can be between 100 amps
and 200 amps. Again, it is determined by the welders skill and comfort
in performing his work.
Metal preparation is the key to making a good weld. The surfaces must
be clean of rust, dirt, grease and grime. Grabbing that wire brush and
scrubbing away like brushing your teeth will go a long way to cleaning
the area to be worked on. If there is a stress crack which is being
welded take a hand grinder and grind a 'V' the length of the crack in
order for the weld to penetrate both sides of the break. After each
pass chip off the slag and debris and wire brush the area before
another weld is made. Cracked areas hiding under splatter, rusty metal
flakes and/or layered metallic garbage should have the debris ground
off so the weld will be made against the parent metal or the most basic
of structure. If there are multi levels of paint on the piece then
take a grinder and work out the paint so the arc will strike easier and
so the weld will have better integrity.
One last note, when the final weld has been cooled and the slag and
debris cleaned off of it inspect it carefully to make sure it did what
you wanted it to. Look for undercutting of the parent metal as this
can form a weak spot in the repair. Make sure you followed the crack
and didn't wander off to the side in the excitement of keeping a good
arc and metallic bead. Check to make sure there is ample bead on the
repair and that any repair plates have good penetration on their edges.
Finally drop a good coat of primer and paint on the repair to protect
the bare metal from the elements. Welded repairs seem to rust quicker
than any other type of exposed metallic areas. Besides a good coat of
paint will look good and make the repair look complete.
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