Harris 4400160 Manual Del Usuario página 4

Welding Rod. Welding rods are available for all types of welding, including
mild steel, cast iron and aluminum, in the following sizes: 1/16", 3/32",
1/8", 5/32", 3/16", 1/4". The size needed will be determined by the
type of weld, the thickness of the metal, and the amount of filler metal
required.
Gas Welding Practices and Exercises. Gas welding is not a difficult art.
The following exercises of torch movement are good practice, and make
subsequent welding easy.
Exercise 1
1. Take a small welding tip and set proper pressures.
2. Point flame directly into steel (Fig. 14) (1/8" stock recommended)
with the flame cone just above the metal surface.
3. When a puddle is formed, move torch back and forth and move the
puddle across the steel. Do this slowly.
4. It is necessary to have good penetration, and this comes from a deep
puddle. It is helpful to lean the tip about 45º away from the direction
you want the puddle to move.
Exercise 2
1. Place two pieces of 1/8" steel together as shown in Figure 15.
2. Make the puddle again and with a back and forth torch motion, move
the puddle along the seam. Go slowly to get good penetration.
Note: This can be checked by turning parts over. The penetration should
be visible from the bottom side. Test the weld strength by attempting to
tear the parts apart.
Figure 14. Exercise 1 Figure 15. Exercise 2
Exercise 3
Note: Repeat Exercise 2, but add welding rod this time.
1. While flame is directed at the steel in order to form the puddle, put
rod into the flame (Fig. 16).
2. When rod gets red, maintain this temperature by moving it in and out
of the flame. Once the weld is started, dip into the puddle. this builds
up the weld so that the top is rounded instead of concave as when no
rod was used.
Note: Remember, welding rod is necessary on all double joints and
once the welder is experienced, he will prefer to use rod on all welds,
regardless of how thin the steel.
3. Material 3/16" or thicker should be bevelled before welding. A 30º
bevel (Fig. 17) on each piece is best. This is necessary to obtain
good penetration through the entire thickness. A rod is necessary
filler metal on all welds made from bevelled edges. Once the torch
movement and puddle control are mastered, the welder can make
vertical, horizontal, or flat welds. He now has a tool that will repay its
cost many times over.
Figure 16. Exercise 3
Braze Welding
Braze welding (FIg. 18) differs from gas welding because the two
pieces of metal are not fused together. The brazing rod melts at a lower
4
60
0
30
0
Figure 17.
Proper 30 Degree bevel for welding
temperature than the parent metal, and the braze strength comes from
the surface overlay of the brazing rod.
The advantage of braze welding over gas welding is that it is the best way
to join dissimilar metals, or repair cast iron. For instance, braze welding
is the correct way to fix a pump water jacket. Almost any two metals can
be joined, except aluminum and magnesium. Braze welding is separated
into two types, depending on the type of rod used.
Bronze Brazing. Bronze is less expensive than silver alloy and should
be used when the fit between the metals to be joined is not close. The
metals must be well cleaned, then the flame is played onto them until
they become a dull red color. Both pieces must be of equal temperature
or the rod will flow to the hotter piece. Heat the rod by placing it in the
flame, then dip into the flux can. Notice that the heat causes the flux to
stick to the rod. If pre-fluxed rod is used, this heating and dipping step
may be eliminated. Once the rod is fluxed, and the metals brought to the
proper temperature, touch the rod to the joint, put the flame onto the rod,
and melt it. The rod then melts and flows over the heated area, bonding
the metal together. Abundant flux must be used. Without enough flux, the
rod will not "stick" to the metals.
Silver Brazing. Silver brazing is a little faster than bronze brazing. This
is because silver alloy melts at a lower temperature, and less heat is
required; however, the joint must fit tightly. Bronze bridges a gap much
better than silver alloy. Instead of putting flux on the rod, the joint should
be painted with the flux. The way to determine when the metals are at
proper temperatures is to watch the flux. when it bubbles, it is time to
apply the rod. The rod melts as it is touched to the metal and flows over
the fluxed area.
Steel Flame Cutting. Steel flame cutting (Fig. 19) is a simple process that
can be quickly mastered. Only carbon steel can be cut with the oxy-fuel
gas method, since cast iron, stainless steel, aluminum, brass and other
ferrous metals do not burn the way steel does.
The way to cut steel is to heat it to its kindling temperature (a red color),
and then burn it rapidly with pure oxygen. A cutting torch provides both
the preheat flames and pure oxygen cutting stream. Fuel gas and oxygen
are combined in the torch head and burn at the torch tip with a flame
temperature of 4000º F - 6000º F. These are the preheat flames. The
center hole in the cutting tip is for the pure oxygen, which flows through
to cut the steel after the metal is sufficiently preheated.
Note: Cutting tips are available in a variety of styles and a wide range of
sizes. The proper size is to be determined by the material thickness to
be cut. Refer to the current product catalog, Tip Chart (P/N 9500593) or
our website at www.harrisproductsgroup.com for a complete listing of
sizes and pressure settings.
Cutting
1. Make certain that correct tip is tightly secured in the torch head.
2. Set proper pressure on regulators.
3. Lighting Procedures:
Figure 18.
Braze Welding
Figure 19.
Steel Flame Cutting