Jeffus Ch09

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OBJECTIVES
After completing this chapter, the student should be able to
discuss the various cutting processes.
give examples of the types of applications that might be best suited to 
specific cutting processes.
list advantages and disadvantages of using the different cutting
processes.
explain the safety considerations of each of the different cutting
processes.
KEY TERMS
abrasives laser beam cuts (LBC)
air carbon arc cutting (CAC-A) laser beam drilling (LBD)
carbon electrode monochromatic
cutting gas assist oxygen lance cutting
delamination solid state lasers
exothermic gases synchronized wave form
gas laser washing
gouging water jet cutting
graphite YAG laser
INTRODUCTION
The number of specialized cutting processes being developed and improved increases
every year. To date there are a number of specialized cutting processes that have been per-
fected and are in use. The new cutting methods are being used by a much wider group than
just the welding industry. These processes can be used to cut a wide variety of things, such
as glass, plastic, printed circuit boards, cloth, and fiberglass insulation, and more things are
being added almost daily. Material cutting and even hole drilling using a welding-related
process have become common in the workplace.
Only a few of the more common cutting processes are covered in this chapter. These are
the ones that a welder might be required to either be able to perform or have a working
knowledge of.
Chapter 9
Related Cutting 
Processes
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Chapter 9 Related Cutting Processes 205
Laser Beam Cutting (LBC)
and Laser Beam Drilling (LBD)
Lasers have developed from the first bright red spot
generated by the ruby rod to a multibillion-dollar indus-
try. The use of lasers has become very common today. We
see their use in our world every day. They help speed our
checking out at stores when they are used to read the uni-
form product code (UPC) on our purchases, Figure 9-1.
Lasers are used by surveyors to measure distances and to
see that a building under construction is level. Doctors
can use lasers to make very precise cuts during the most
delicate operations. They are even used to entertain us at
shows and concerts.
Manufacturers use the laser to do everything from
marking products, joining parts, communicating between
machines, guiding, cutting, or punching machines to cut-
ting a variety of materials. The industrial laser can be used
to guide a machine’s cut accurately or to measure dis-
tances from a few hundred to thousands of miles.
This versatile tool has helped produce products that
could not be produced without the laser’s light. A laser
can be used to drill holes (LBD) through the hardest mate-
rials, such as synthetic diamonds, tungsten carbide cut-
ting tools, quartz, glass, or ceramics. Lasers are used for
welding (LBW) materials that are too thin or too hard to
be welded with other heat sources. They can be used to
cut (LBC) materials that must be cut without overheating
delicate parts that might be located just a few thousands
of an inch away.
The benefits and capacities of the laser have made it
one of the most rapidly growing areas in manufacturing.
This is a useful tool that will continue to be developed and
improved for years to come.
Lasers
A laser is a form of light that is monochromatic, a sin-
gle color wavelength, that travels in parallel waves, Figure
9-2. This form of light is generated when certain types of
materials are excited either by intense light or with an elec-
tric current. The atoms or molecules of the lasing material
release their energy in the form of light. The laser light is
produced as the atom or molecule slows down from a high
energy state to a lower energy state, Figure 9-3. The laser
light is then bounced back and forth between one fully
reflective and one partially reflective surface at the ends of
the lasing material. As the light is reflected, it begins to form
a synchronized wave form. The light that passes through
the partially reflective mirror is the laser light, and it is
ready to do its job, Figure 9-4.
Once the laser beam emerges from the laser rod or
chamber, it can be treated as any other type of light. It is
possible to focus, reflect, absorb, or defuse the light. By
having the light waves traveling in such a uniform man-
ner, they exhibit some specialized characteristics. The
light beam tends to remain in a very tight column without
spreading out, as does ordinary light, Figure 9-5. This
characteristic allows the laser beam to travel over some
distance without significantly being affected by the dis-
tance it travels or the air it is traveling through.
Because the beam is not adversely affected by its travel,
it can be used to carry information or transmit energy.
When the laser wraps around a loaf of bread or a box 
of crackers, its image is so precise that the data in a uni-
form product code strip can accurately be received by
the store’s computer. The military uses lasers to aim
weapons or identify targets so that they can be hit by
missiles or bombs.
Laser Types The early lasers all used a synthetic ruby rod
as the material that produced the laser light. Today a large
number of materials can be used to produce the laser. These
FIGURE 9-1 Bar codes are read by lasers to input infor-
mation into computers.
WHITE LIGHT
LASER LIGHT
FIGURE 9-2 White light is made up of different fre-
quencies (colors) of light waves. Laser light is made up
of single frequency light waves traveling parallel to
each other.
CO2 
MOLECULE
LIGHT 
ENERGY 
INPUT
LASER
ENERGY 
INPUT
O
C
O
FIGURE 9-3 Energy is stored in a carbon dioxide (CO2)
molecule until the molecule can’t hold any more. The 
energy is released suddenly like when a balloon pops. 
This quick release results in a burst of light energy.
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206 Section 3 Cutting and Gouging
materials include such common items as glass and such
exotic items as neodymium-doped, yttrium aluminum gar-
net (Nd-YAG), often referred to as a YAG laser, Figure 9-6.
Lasers can be divided into two major types; lasers using
a solid material for the laser and lasers using a gas. Each
of these two types is divided into two groups based on
their method of operation: lasers that operate continu-
ously and lasers that are pulsed.
Solid State Lasers The first lasers were all solid state
lasers. They used a ruby rod to produce the laser. Today the
most popular solid laser is the neodymium-doped, yttrium
aluminum garnet (YAG). This is a synthetic crystal that
when exposed to the intense light from the flash tubes can
produce high quantities of laser energy. The high-powered
solid lasers have a problem because the internal tempera-
tures of the laser rod increase with operation time. These
lasers are most often used with low-power continuous or
high-powered pulse. The solid state laser is capable of gen-
erating the highest-powered laser pulses.
Gas Laser The gas laser uses one or more gases for the
laser. Popular gas-type lasers use nitrogen, helium, car-
bon dioxide (CO2), or mixtures of helium, nitrogen, and
CO2. Gas lasers either use a gas-charged cylinder where
the gas is static or use a chamber that has a means of cir-
culation of the laser gas. The highest continuous power
output-type lasers are the gas type with a blower to circu-
late the gas through a heat exchanger; they can be rapidly
pulsed to improve their cutting capacity, Figure 9-7.
Applications
Laser light beams can be focused into a very compact
area. This allows the photo energy that the light possesses
FRONT MIRROR 
LIGHT
INPUT
REAR MIRROR 
FIGURE 9-4 Light energy reflects back and forth between the end mirrors until it forms a parallel laser light beam.LASER LIGHT
FLASH LIGHT
FIGURE 9-5 Laser light stays in a very tight column
unlike most other lights.
CHILLER
ENERGY 
MONITOR
BEAM
DUMP 
VIEWING HEAD
BEAM EXPANDING
TELESCOPE
WORKPIECE
SAFETY
 MIRROR
45°
 MIRROR
FOCUSING 
LENS
SHUTTER
FRONT 
MIRRORLASER ROD ANDFLASHLAMPS
REAR 
MIRROR
FIGURE 9-6 Schematic representation of the elements of a Nd–YAG laser. Courtesy of the American Welding Society.
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Chapter 9 Related Cutting Processes 207
to be converted to heat energy as it strikes the surface of a
material. The highly concentrated energy can cause the
instantaneous melting or vaporization of the material
being struck by the laser beam. The equipment used to
produce laser beam welds (LBW), laser beam cuts
(LBC), or laser beam drilling (LBD) is similar in design
and operation. Most laser welding and cutting operations
use a gas laser, and most drilling operations use a solid
state laser.
In all of the laser applications the ability of the surface
of the material to either absorb or reflect the laser greatly
affects the operation’s efficiency. All materials will reflect
some of the laser’s light more than others. The absorption
rate will increase for any material once the laser beam
begins to heat the surface. Once the threshold of the sur-
face temperature is reached, the process will continue at a
much higher level of efficiency.
Laser Beam Cutting
A laser weld and laser cut both bring the material to a
molten state. In the welding process the material is
allowed to flow together and cool to form the weld metal.
In the cutting process a jet of gas is directed into the
molten material to expel it through the bottom of the cut.
Although the laser is used primarily to cut very thin mate-
rials, it can be used to cut up to 1 inch of carbon steel.
The cutting gas assist can be either a nonreactive gas
or an exothermic. Table 9-1 lists the various gases and the
materials that they are used to cut. Nonreactive gases do
not add any heat to the cutting process; they simply
remove the molten material by blowing it out of the kerf.
Exothermic gases react with the material being cut, like
an oxyfuel cutting torch. The additional heat produced as
the exothermic cutting gas reacts with the metal being cut
helps blow the molten material out of the kerf.
Some of the advantages of laser cutting include
■ narrow heat-affected zone—Little or no heating of
the surrounding material is observed. It is possible
to make very close parallel cuts without damaging
the strip that is cut out, Figure 9-8.
■ no electrical conductivity required—The part being
cut does not have to be electrically conductive, so
materials like glass, quartz, and plastic can be cut.
There is also no chance that a stray electrical charge
might damage delicate computer chips while they
are being cut using a laser.
■ noncontact—Nothing comes in contact with the part
being cut except the laser beam. Small parts that may
have finished surfaces or small surface details can be
cut without the danger of disrupting or damaging the
surface. It is also not necessary to hold the parts
securely as it is when a cutting tool is used.
■ narrow kerf—The width of the kerf is very small,
which allows the nesting of parts in close proximity
to each other, which will reduce waste of expensive
materials, Figure 9-9.
GAS CLOUD
HOT SPARKS
PULSED
LASER BEAM
FIGURE 9-7 The gas cloud and hot sparks caused by the
cutting laser beam dissipate between the pulses of the
laser beam, which results in a better cut.
Assist Gases Material
Air Aluminum
Plastic
Wood
Composites
Alumina
Glass
Quartz
Oxygen Carbon steel
Stainless steel
Copper
Nitrogen Stainless steel
Aluminum
Nickel alloys
Argon Titanium
TABLE 9-1 Various Cutting Assist Gases and the
Materials They Cut.
FIGURE 9-8 Detailed small part not much larger than a
dime made with a laser. Courtesy of Larry Jeffus.
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208 Section 3 Cutting and Gouging
■ automation and robotics—The laser beam can easily
be directed through an articulated guide to the work-
ing end of an automated machine or a robot.
■ top edge—The top edge will be smooth and square
without being rounded.
Laser Beam Drilling
The pulsed laser is the best choice for drilling opera-
tions. A very short burst of high laser energy is concen-
trated on a small spot. The intense heat vaporizes the
small spot with enough force to thrust the material out,
leaving a small crater. The repeated blasting to the pulsed
laser results in the crater becoming increasingly deeper.
This process continues until the hole is drilled through
the part or to a desired depth, Figure 9-10.
A laser can be used to drill holes through the hardest
materials, such as tungsten carbide cutting tools, quartz,
glass, ceramics, or even synthetic diamonds. No other
drilling process can match the precision, speed, or econ-
omy of the laser drill.
Holes as small as 0.0001 inch in diameter can be
drilled. The limitation on the hole’s depth is the laser’s
focal length. Most holes are less than 1 inch in depth.
Laser Equipment
Most lasers range from 400 to 1500 watts in power.
Some large machines have as much as 25 KW of power.
Although the power of most lasers is relatively small,
when compared to other welding processes, it is the laser’s
ability to concentrate the power into a small area that
makes it work so well. The power density of a cutting laser
can be equal to 65 million watts per square inch.
Laser equipment is larger than most of the other welding
or cutting power supply. A typical unit will require about as
much floor space as a large desk, about 10 square feet.
Recent advancements, increased competition, and a
rapidly increasing market have helped lower the high cost
of the equipment. But even with the current cost of equip-
ment, laser cutting and drilling have one of the lowest
average hourly operating costs. The high reliability and
long life of the equipment has also helped reduce operat-
ing costs.
Air Carbon Arc Cutting
The air carbon arc cutting (CAC-A) process was
developed in the early 1940s and was originally named air
arc cutting (AAC). Air carbon arc cutting was an improve-
ment of the carbon arc process. The carbon arc process
was used in the vertical and overhead positions and
removed metal by melting a large enough spot so gravity
would cause it to drip off the base plate, Figure 9-11. This
process was slow and could not be accurately controlled.
It was found that by using a stream of air the molten metal
could be blown away. This greatly improved the speed,
quality, and controllability of the process.
In the late 1940s the first air carbon arc cutting torch
was developed. Before this development the process
required two welders, one to control the carbon arc and
FIGURE 9-9 Because of the narrow kerf, small, detailed
parts can be nested one inside the other. Courtesy of Larry
Jeffus.
LASER
DRILLED
HOLES
FIGURE 9-10 Jet engine blades and a rotor component
showing laser drilled holes. Courtesy of the American Welding
Society.
RIVET
ARC
CARBON
ELECTRODE
FIGURE 9-11 A carbon electrode was used to melt the
head off rivets.
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Chapter 9 Related Cutting Processes 209
the other to guide the air stream. The new torch had
both the carbon electrode holder and the air stream in
the same unit. This basic design is still in use today,
Figure 9-12.
Unlike the oxyfuel process, the air carbon arc cutting
process does not require that the base metal be reactive
with the cutting stream. Oxyfuel cutting can only be per-
formed on metals that can be rapidly oxidized by the cut-
ting stream of oxygen. The air stream in this processblows the molten metal away. This greatly increases the
list of metals that can be cut, Table 9-2.
Manual Torch Design
The air carbon arc cutting torch is designed differently
than the shielded metal arc electrode holder. The major
differences between an electrode holder and an air carbon
arc torch are
■ The lower electrode jaw has a series of air holes.
■ The jaw has only one electrode locating groove.
■ The electrode jaw can pivot.
■ There is an air valve on the torch lead.
INSULATOR
INSULATOR
LEVER
AIR VALVE
HANDLE
CONDUCTOR
COMPRESSED
 AIR
CABLE COVER
FEMALE 
CONNECTOR
BODY
HEADELECTRODE
FIGURE 9-12 Typical cross section of an air carbon arc gouging torch. Courtesy of the American Welding Society.
Base Metals Recommendations
Carbon steel and low alloy steel Use DC electrodes with DCEP current. AC can be used but with a 
50% loss in efficiency.
Stainless steel Same as for carbon steel.
Cast iron, including malleable and ductile iron Use of 1/2″ or larger electrodes at the highest rated amperage is 
necessary. There are also special techniques that need to be used 
when gouging these metals. The push angle should be at least 
70° and depth of cut should not exceed 1/2 inch per pass.
Copper alloys (copper content 60% and under) Use DC electrodes with DCEN (electrode negative) at maximum 
amperage rating of the electrode.
Copper alloys (copper content over 60%, or size of workpiece Use DC electrodes with DCEN at maximum amperage rating of 
is large) the electrode or use AC electrodes with AC.
Aluminum bronze and aluminum nickel bronze (special naval Use DC electrodes with DCEN.
propeller alloy)
Nickel alloys (nickel content is over 80%) Use AC electrodes with AC.
Nickel alloys (nickel content less than 80%) Use DC electrodes with DCEP.
Magnesium alloys Use DC electrodes with DCEP. Before welding, surface of groove 
should be wire brushed.
Aluminum Use DC electrodes with DCEP. Wire brushing with stainless wire 
brushes is mandatory prior to welding. Electrode extension 
(length of electrode between electrode torch and workpiece) 
should not exceed 3 inches for good-quality work. DC electrodes 
with DCEN can also be used.
Titanium, zirconium, hafnium, and their alloys Should not be cut or gouged in preparation for welding or 
remelting without subsequent mechanical removal of surface 
layer from cut surface.
Note: Where preheat is required for welding, similar preheat should be used for gouging.
TABLE 9-2 Recommended Procedures for Air Carbon Arc Cutting of Different Metals.
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210 Section 3 Cutting and Gouging
By having only one electrode locating groove in the jaw
and pivoting the jaw, the air stream will always be aimed
correctly. The air must be aimed just under and behind the
electrode and always in the same direction, Figure 9-13.
This ensures that the air stream will be directed at the spot
where the electrode arcs to base the metal.
Torches are available in a number of amperage sizes.
The larger torches have greater capacity but are less flexi-
ble to use on small parts.
The torch can be permanently attached to a welding
cable and air hose or it can be attached to welding power
by gripping a tab at the end of the cable with the shielded
metal arc electrode holder, Figure 9-14. The temporary
attachment can be made easier if the air hose is equipped
with a quick disconnect. A quick disconnect on the air
hose will allow it to be used for other air tools such as
grinders or chippers. Greater flexibility for a work station
can be achieved with this arrangement.
Electrodes Air carbon arc cutting electrodes are avail-
able as copper-coated or plain (without a coating). The
copper coating helps decrease the carbon electrode
overheating by increasing its ability to carry higher cur-
rents and improves the heat dissipation. The copper
coating provides increased strength, to reduce acciden-
tal breakage.
Electrodes come in round, flat, and semiround, Figure
9-15. The round electrodes are used for most gouging
operations, and the flat electrodes are most often used to
scarf off a surface. Round electrodes are also available in
sizes ranging from 1/8 to 1 inch in diameter. Flat elec-
trodes are available in 3/8- and 5/8-inch sizes.
Electrodes are available to be used on both direct-
current electrode positive and alternating current. The
DCEP electrodes are the most commonly used, and they
are made of carbon in the form of graphite. The AC
electrodes are less common; they have some elements
added to the carbon to stabilize the arc, which is needed
for the AC power.
To reduce waste, electrodes are made so that they can
be joined together. The joint consists of a female tapered
socket at the top end and a matching tang on the bottom
end, Figure 9-16. The connection of the new electrode to
the remaining setup will allow the stub to be consumed
with little loss of electrode stock. This connecting of elec-
trodes is required for most track-type air carbon arc cut-
ting operations to allow for longer cuts.
Power Sources Most shielded metal arc welding
power supplies can be used for air carbon arc cutting. The
operating voltage required for air carbon arc cutting needs
CARBON
ELECTRODE
AIR JET
FIGURE 9-13 Air carbon arc gouging.
COMPRESSED AIR
ELECTRODE LEAD
DCEP OR AC
CONCENTRIC
CABLE
TORCH
WORKPIECE LEAD
CARBON 
ELECTRODE
WORKPIECE
POWER SUPPLY
FIGURE 9-14 Air carbon arc gouging equipment setup.
Courtesy of the American Welding Society.
ROUND SEMI-ROUNDFLAT
FIGURE 9-15 Cross sections of carbon electrodes.
STARTING TIP OF
NEW ELECTRODE
END OF OLD ELECTRODE
FIGURE 9-16 Air carbon arc electrode joint.
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Chapter 9 Related Cutting Processes 211
to be 28 volts or higher. This voltage is slightly higher
than that required for most SMA welding, but most
welders will meet this requirement. Check the manufac-
turer’s owner’s manual to see if your welder is approved
for air carbon arc cutting. If the voltage is lower than the
minimum, the arc will tend to sputter out, and it will be
hard to make clean cuts.
Because most carbon arc cutting requires a high amper-
age setting, it may be necessary to stop some cuts so that
the duty cycle of the welder is not exceeded. On large
industrial welders this is not normally a problem.
Air Supply Air supplied to the torch should be between
80 and 100 psi. The minimum pressure is around 40 psi.
The correct air pressure will result in cuts that are clean,
smooth, and uniform. The air flow rate is also important.
If the air line is too small or the compressor does not have
the required capacity, there will be a loss in air pressure at
the torch tip. This line loss will result in a lower than
required flow at the tip. The resulting cut will be less
desirable in quality.
Application Air carbon arc cutting can cut a variety
of materials. It is a relatively low-cost way of cutting
most metals, especially stainless steel, aluminum, nickel
alloys, and copper. Air carbon arc cutting is most often
used for repair work. Few cutting processes can match
the speed, quality, and cost savings of this process for
repair or rework. In repair or rework, the most difficult
part is the removal of the old weld or cutting a groove so
a new weld can be made. The air carbon arc can easily
remove the worst welds even if they contain slag inclu-
sions or other defects. For repairs the arc can cut
through thin layers of paint, oil, or rust and make a
groove that needs little, if any, cleanup.
/ / / C AU T I O N \ \ \
Never cut on any material that might produce
fumes that would be hazardous to your health
without proper safety precautions, including
adequate ventilation and/or the wearing of a
respirator.
Thehighly localized heat results in only slight heating
of the surrounding metal. As a result, usually there is no
need to preheat hardenable metals to prevent hardness
zones. Cast iron is a metal that can be carbon arc gouged
to prepare a crack for welding without causing further
damage to the part by inputting excessive heat.
Air carbon arc cutting can be used to remove a weld
from a part. The removal of welds can be accomplished
with such success that often the part needs no postcut
cleanup. The root of a weld can be back gouged so that a
backing weld can be made ensuring 100% weld penetra-
tion, Figure 9-17.
The electrode should extend approximately 6 inches from
the torch when starting a cut and, as the cut progresses, the
electrode is consumed. Stop the cut and readjust the elec-
trode when its end is approximately 3 inches from the elec-
trode holder. This will reduce the damage to the torch caused
by the intense heat of the operation.
Gouging Gouging is the most common application of
the air carbon arc cutting processes. Arc gouging is the
removal of a quantity of metal to form a groove or bevel,
Figure 9-18. The groove produced along an edge of a plate
is usually a J-groove. The groove produced along a joint
between plates is usually a U-groove, Figure 9-19. Both
grooves are used as a means to ensure that the weld
applied to the joint will have the required penetration into
the metal.
Washing Washing is the process sometimes used to
remove large areas of metal so that hard surfacing can be
applied, Figure 9-20. Washing can be used to remove
large areas that contain defects, to reduce the transitional
stresses of unequal-thickness plates, or to allow space for
the capping of a surface with a wear-resistant material.
UNFUSED ROOT
BACK GOUGED ROOT
FIGURE 9-17 Back gouging the root of a weld made in
thick metal can ensure that a weld with 100% joint
fusion can be made.
TRA
VEL
FIGURE 9-18 Manual air carbon arc gouging operation
in the flat position. Courtesy of the American Welding Society.
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212 Section 3 Cutting and Gouging
Safety
In addition to the safety requirements of shielded metal
arc, air carbon arc requires several special precautions,
such as
■ sparks—The quantity and volume of sparks and
molten metal spatter generated during this process
is a major safety hazard. Extra precautions must be
taken to ensure that other workers, equipment,
materials, or property in the area will not be
affected by the spark stream.
■ noise—This process produces a high level of sound.
The sound level is high enough to cause hearing
damage if proper ear protection is not used.
■ light—The arc light produced is the same as that
produced by the shielded metal arc welding
process. But because the arc has no smoke to defuse
the light and the amperages are usually much
higher, the chances of receiving arc burns are much
higher. Additional protection should be worn, such
as thicker clothing, a leather jacket, and leather
aprons.
■ eyes—Because of the intense arc light, a darker
welding filter lens for the helmet should be used.
■ fumes—The combination of the air and the metal
being removed result in a high volume of fumes.
Special consideration must be made for the removal
of these fumes from the work area. Before installing
a ventilation system, check with local, state, and
federal laws. Some of the fumes may have to be fil-
tered before they can be released into the air.
■ surface contamination—Often this process is used
to prepare damaged parts so that they can be
repaired. If the used parts have paint, oils, or other
contamination that might generate hazardous
fumes, they must be removed in an acceptable man-
ner before any cutting begins.
■ equipment—Check the manufacturer’s owner’s man-
ual for specific safety information concerning the
power supply and the torch before you start any work
with each piece of equipment for the first time.
PRACTICE 9-1
Air Carbon Arc Straight Cut 
in the Flat Position
Using an air carbon arc cutting torch and welding
power supply that has been safely set up in accordance
with the manufacturer’s specific instructions in the
owner’s manual and wearing safety glasses, welding hel-
met, gloves, and any other required personal protection
clothing, you will make a 6-inch-long straight U-groove
gouge in a carbon steel plate.
1. Adjust the air pressure to approximately 80 psi.
2. Set the amperage within the range for the diame-
ter electrode you are using by referring to the box
the electrodes came in.
3. Check to see that the stream of sparks will not
start a fire or cause any damage to anyone or any-
thing in the area.
4. Make sure the area is safe, and turn on the welder.
5. Using a good dry leather glove to avoid electrical
shock, insert the electrode in the torch jaws so
that about 6 inches is extending outward. Be sure
not to touch the electrode to any metal parts,
because it may short out.
6. Turn on the air at the torch head.
7. Lower your arc welding helmet.
8. Slowly bring the electrode down at about a 30°
angle so it will make contact with the plate near
J-GROOVE
U-GROOVE
FIGURE 9-19 Air carbon arc gouging groove shapes.
ELECTRODE
HOLDER
MOTION
FIGURE 9-20 Hardsurfacing weld applied in the carbon-
arc-cut groove. Courtesy of the American Welding Society.
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Chapter 9 Related Cutting Processes 213
the starting edge, Figure 9-21. Be prepared for a
loud, sharp sound when the arc starts.
9. Once the arc is struck, move the electrode in a
straight line down the plate toward the other end.
Keep the speed and angle of the torch constant.
10. When you reach the other end, lift the torch so
the arc will stop.
11. Raise your helmet and stop the air.
12. Remove the remaining electrode from the torch
so it will not accidentally touch anything.
When the metal is cool, chip or brush any slag or dross
off of the plate. This material should remove easily. The
groove must be within �1/8 inch of being straight and
within �3/32 inch of uniformity in width and depth.
Repeat this cut until it can be made within these toler-
ances. Turn off the CAC equipment and clean up your
work area when you are finished cutting.
Complete a copy of the “Student Welding Report” listed
in Appendix I or provided by your instructor. ◆
PRACTICE 9-2
Air Carbon Arc Edge Cut 
in the Flat Position
Using the same equipment, adjustments, setup, and
materials as described in Practice 9-1, you are going to
make a J-groove along the edge of the plate.
1. Adjust the air pressure to approximately 80 psi.
2. Set the amperage within the range for the diame-
ter electrode you are using.
3. Check to see that the stream of sparks will not
start a fire or cause any damage to anyone or any-
thing in the area.
4. Make sure the area is safe, and turn on the welder.
5. Using a good, dry, leather glove to avoid electri-
cal shock, insert the electrode in the torch jaws
so that about 6 inches is extending outward. Be
sure not to touch the electrode to any metal parts
because it may short out.
6. Turn on the air at the torch head.
7. Lower your arc welding helmet.
8. Slowly bring the electrode down at about a 30°
angle so it will make contact with the plate near
the starting edge, Figure 9-22.
9. Once the arc is struck, move the electrode in a
straight line down the edge of the plate toward
the other end. Keep the speed and angle of the
torch constant.
10. When you reach the other end, lift the torch so
the arc will stop.
11. Raise your helmet and stop the air.
12. Remove the remaining electrode from the torch
so it will not accidentally touch anything.
When the metal is cool, chip or brush any slag or dross
off of the plate. This materialshould remove easily. The
groove must be within �1/8 inch of being straight and
within �3/32 inch of uniformity in width and depth.
Repeat this cut until it can be made within these toler-
ances. Turn off the CAC equipment and clean up your
work area when you are finished cutting.
Complete a copy of the “Student Welding Report” listed
in Appendix I or provided by your instructor. ◆
30°
FIGURE 9-21 Air carbon arc U-groove gouging.
FIGURE 9-22 Air carbon arc J-groove gouging.
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214 Section 3 Cutting and Gouging
PRACTICE 9-3
Air Carbon Arc Back Gouging 
in the Flat Position
Using the same equipment, adjustments, setup, and
materials as described in Practice 9-1, you are going to
make a U-groove along the root face of a weld joint on a
plate, Figure 9-23.
Follow the same starting procedure as you did in
Practice 9-1.
1. Start the arc at the joint between the two plates.
2. Once the arc is struck, move the electrode in a
straight line down the edge of the plate toward the
other end. Watch the bottom of the cut to see that
it is deep enough. If there is a line along the bot-
tom of the groove, it needs to be deeper. Once the
groove depth is determined, keep the speed and
angle of the torch constant.
3. When you reach the other end, break the arc off.
4. Raise your helmet and stop the air.
5. Remove the remaining electrode from the torch so
it will not accidentally touch anything.
When the metal is cool, chip or brush any slag or dross
off of the plate. This material should remove easily. The
groove must be within �1/8 inch of being straight, but it
may vary in depth so that all of the unfused root of the weld
has been removed. Repeat this cut until it can be made
within these tolerances. Turn off the CAC equipment and
clean up your work area when you are finished cutting.
Complete a copy of the “Student Welding Report” listed
in Appendix I or provided by your instructor. ◆
PRACTICE 9-4
Air Carbon Arc Weld Removal 
in the Flat Position
Using the same equipment, adjustments, setup, and
materials as described in Practice 9-1, you are going 
to make a U-groove to remove a weld from a plate,
Figure 9-24.
1/4" OR 1/2" X 6" MILD STEEL PLATE
AIR CARBON ARC BACK GOUGING
PRACTICE 9–3 RANDY ZAJIC
CAC-A
Welding Principles and Applications
MATERIAL:
PROCESS:
NUMBER: DRAWN BY:
FIGURE 9-23 Air carbon arc back gouging.
CAC-A
Welding Principles and Applications
MATERIAL:
1/4" OR 1/2" X 6" MILD STEEL PLATE
AIR CARBON ARC GOUGING
PRACTICE 9–4 BETH VANCE
PROCESS:
NUMBER: DRAWN BY:
FIGURE 9-24 Air carbon arc weld gouging.
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Chapter 9 Related Cutting Processes 215
Follow the same starting procedure as you did in
Practice 9-1.
1. Start the arc on the weld.
2. Once the arc is struck, move the electrode in a
straight line down the weld toward the other end.
Watch the bottom of the cut to see that it is deep
enough. If there is not a line along the bottom of
the groove, it needs to be deeper. Once the groove
depth is determined, keep the speed and angle of
the torch constant.
3. When you reach the other end, break the arc off.
4. Raise your helmet and stop the air.
5. Remove the remaining electrode from the torch so
it will not accidentally touch anything.
When the metal is cool, chip or brush any slag or
dross off of the plate. This material should remove eas-
ily. The groove must be within �1/8 inch of being
straight, but it may vary in depth so that all of the weld
metal has been removed. Repeat this cut until it can be
made within these tolerances. Turn off the CAC equip-
ment and clean up your work area when you are fin-
ished cutting.
Complete a copy of the “Student Welding Report” listed
in Appendix I or provided by your instructor. ◆
Oxygen Lance Cutting
The oxygen lance cutting process uses a consumable
alloy tube, Figure 9-25. The tip of the tube is heated to
its kindling temperature. A high-pressure oxygen flow is
started through the lance. The oxygen reacts with the
hot lance tip, releasing sufficient heat to sustain the reac-
tion, Figure 9-26.
The rod tip is heated up to a red hot temperature using
an oxyfuel torch or electric resistance. Once the oxygen
stream is started, it reacts with the lance material, which
results in the creation of both a high temperature and
heat-releasing reaction.
The intense reaction of the lance allows it to be used to
cut through a variety of materials. The hot metal leaving
the lance tip has not completed its exothermic reaction.
As this reactive mass impacts the surface of the material
being cut, it releases a large quantity of energy into that
surface. Thermal conductivity between the molten metal
and the base material is a very efficient method of heat
transfer. This, along with the continued burning of the
lance material on the surface, causes the base material to
become molten.
Once the base material is molten, it may react with the
burning lance material, forming fumes or slag, which is
then blown from the cut. Any molten material not becom-
ing reactive is carried out of the cut with the slag or blown
out with the oxygen stream.
The addition of steel rods or other metals to the center
of the oxygen lance tube have increased their productivity.
The improved lances last longer and cut faster.
TO
 TORCH
OXYGEN LANCE ROD
TO
 STRIKER
POWER SUPPLY
OXYGEN LEVER
TORCH
STRIKER
FROM OXYGEN REGULATOR 
FIGURE 9-26 Arcair® SLICE® portable cutting system
that uses sparks created between the striker and tube
to ignite the oxygen lance rod for cutting. Courtesy of
Arcair® a Thermodyne® Company.
FIGURE 9-25 Oxygen lance rods may be rolled out of flat
strips of special alloys to form a tube. Courtesy of Arcair® a
Thermodyne® Company.
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216 Section 3 Cutting and Gouging
Application
The oxygen lance’s unique method of cutting allows
it to be used to cut material not normally cut using a
thermal process. Films have portrayed the oxygen lance
as a tool used by thieves to cut into safes. In reality, this
would result in the valuables in the safe being
destroyed. The oxygen lances can be used to cut rein-
forced concrete.
Cutting concrete has been used in the demolition of
buildings. It allows the quick removal of thick sections
of the building without the dangerous vibration caused
by most conventional methods. This has been a life-
saving factor in the use of the oxygen lance for rescue
work following earthquakes. The oxygen lance saved
thousands of hours and countless lives in Mexico City
following the devastation from the city’s worst earth-
quake. Oxygen lances were used to cut large sections of
concrete that fell from buildings into manageably sized
pieces. Local and national news agencies showed build-
ing rubble being cut away by rescue workers using the
oxygen lance.
The oxygen lance is also used to cut thick sections of
cast iron, aluminum, and steel. Often in the production
of these metals thick sections must be cut. Occasionally
equipment failure will stop metal production. If the
metal in production is allowed to cool, it may need to be
cut in sections so it can be removed from the machine.
The oxygen lances process is very effective in this type of
work.
Safety It is important to follow all safety procedures
when using this process. Manufacturers list specific safety
precautions for the oxygen lances they produce. Read and
follow those instructions carefully. The major safety con-
cerns are
■ fumes—The large quantity of fumes generated are
often a health hazard. An approved ventilation sys-
tem must be provided if this work is to be done in a
building or any other enclosed area.
■ heat—This operation producesboth high levels of
radiant heat and plumes of molten sparks and slag.
The operators must wear special heat-resistant
clothing.
■ noise—Sound is produced well above safety levels.
Ear protection must be worn by anyone in the
area.
Water Jet Cutting
Water jet cutting is not a thermal cutting process. This
method of cutting does not put any heat into the material
being cut. The cut is accomplished by the rapid erosion of
the material by a high-pressure jet of water, Figure 9-27.
An abrasive powder may be added to the stream of water.
Abrasives are added when hard materials such as metals
are being cut.
The lack of heat input to the material being cut makes
this process unique. Materials that heat might distort,
make harder, or cause to delaminate are ideally suited to
this process. The lack of heat distortion allows thin
material to be cut with the edge quality of a laser cut and
as distortion free as a shear cut. Delamination is not a
problem when cutting composite or laminated materials,
such as carbon fibers, resins, or computer circuit boards,
Figure 9-28.
FIGURE 9-27 Basic diagram illustrating the elements of
the waterjet cutting system. Courtesy of Ingersoll-Rand.
FIGURE 9-28 Waterjet cutting is very versatile. A
machine with multiple cutting jets is cutting out printed
circuit boards. Courtesy of Ingersoll-Rand.
52752_09_Ch09_204-219.qxd 2/2/07 12:52 PM Page 216
admin
Note
place at top of second column
Chapter 9 Related Cutting Processes 217
Applications
The kerf width does not tend to change unless too
high a travel speed is being used. This results in a square,
smooth finish on the cut surface. Postcut cleanup of the
parts is totally eliminated for most materials, and only
slight work is needed on a few others, Figure 9-29. The
quality of the cut surface can be controlled so that even
parts for the aerospace industry can often be assembled
as cut.
The addition of an abrasive powder can speed up the
cutting, allow harder materials to be cut, and improve the
surface finish of a cut. The powder most often used is gar-
net. It is also commonly used as an abrasive on sandpaper.
If an abrasive is used, the small water jet orifice will wear
out faster.
Materials that often gum up a cutting blade, such as
plexiglass, ABS plastic, and rubber, can be cut easily.
There is nothing for the material to adhere to that would
disrupt the cut. The lack of heat also reduces the ten-
dency of the material cut surface to become galled.
Most of the water jet cutting is performed by some
automated or robotic system. There are a few bandsaw-
type, hand-fed cutting machines that are used for single
cuts or when limited production is required.
Summary
The welding field’s ability to provide industry with a
wide variety of cutting processes has increased productiv-
ity for a variety of industries. An example of this diversity
is the use of a laser beam to cut apart computer chips in
the electronics field. Without these cutting processes
industry would have to rely on the much slower and more
expensive mechanical or abrasive cutting process. There
are no mechanical or abrasive cutting processes that can
compete with the speed of these new cutting processes
and none that can compete with their versatility.
Somewhat less attractive but nonetheless efficient
processes such as carbon arc gouging and oxygen
lance cutting fulfill specific industrial applications,
such as salvage or scrap work. Few cutting processes
can rival the metal removing capacity of the air car-
bon arc or oxygen lance processes. In addition, the
low cost of the equipment and the flexibilities and
application of these processes have lent themselves
very successfully to the salvage and scrap industry.
Air carbon arc gouging is extensively used for weld
removal and repair work. A skilled technician can
produce a groove that requires little or no postcut
cleanup prior to rewelding.
FIGURE 9-29 Notice how narrow and clean this cut is.
Courtesy of Ingersoll-Rand.
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218 Section 3 Cutting and Gouging
Lasers: The New Wave 
in Ship Construction
During the past ten years, laser materials processing has
been accepted into a number of industries. The automotive,
medical device, electronics, and consumer products indus-
tries have developed laser materials processes and designs to
improve product performance. With advances in hardware
and processing, lasers are now making inroads into industries
with new material and fabrication demands. These industries
include heavy machinery, construction equipment, aero-
space, oil/chemical, power generation, and shipbuilding.
Laser materials processing uses the energy of photon-mat-
ter interaction to heat a targeted material. The density and
interaction time of the laser beam with the material deter-
mines what process is accomplished. At lower power densities
and longer interaction times, the laser can be used to heat
treat or thermally form materials. As the power density is
increased, materials can be melted to form resolidified or clad
surfaces. At higher power densities and shorter interaction
times, the laser can produce a keyhole in the molten material
and achieve deep penetration welds with very high depth-to-
width ratios. Further modification of the interaction can result
in cutting and drilling with very little heat input into the part.
The advantages of using lasers are determined by what
process is needed. At lower power densities, the laser has an
advantage over induction and furnace heating because of its
accuracy in treating specific areas, which can minimize ther-
mal impact to surrounding materials. At higher power densi-
ties, heat input can be accurately controlled, permitting
high-quality clads and direct material buildups. In welding,
the laser permits deep welds to be made with very low heat
input at very high speeds. The result is weld joints with low
impact to the surrounding materials and low distortion.
While other processes can cut faster (oxyfuel or plasma) or
without heat (water jet), the laser is flexible and precise for a
wide range of thicknesses and types of metals and nonmetals.
The possible use of lasers in shipbuilding has been of inter-
est for a number of years. In the past, the U.S. Navy conducted
studies on how lasers could be used for cutting and fabricat-
ing Navy combatants and submarines and what impact that
would have on the materials used in naval structures. Most of
these applications were based on the use of high-power CO2
lasers and complex delivery systems. The Navy determined
that equipment and operational costs, reliability, and return
on investment for such applications did not justify their use.
Since these early studies, there have been improvements
in laser systems that have had a positive impact on laser
applications in thick-section materials. First, changes in laser
designs have increased beam quality and have improved
laser welding and cutting capabilities. Second, lasers have
become more “industrialized” through improvements in
design and standardization of components. Third, the cost
has decreased in real dollar terms. Other industries, such as
automotive and sheet metal fabrication, where laser pro-
cessing has been easier to justify, have driven these changes.
One factor that has limited the insertion of laser processing
into ship applications has been the lack of standards and spec-
ifications. ASME and AWS have specifications for pressure
structures and recommended practices, respectively, but
there are few widely accepted standards for laser-fabricated
structures. The International Organization for Standardization
(ISO) has been developing specifications for laser cut quality
and laser cutting systems. In the United States, the AWS C7C
Committee is developing general laser processing specifica-tions. The U.S. Navy, in previous efforts, has accepted laser
processing only for specific applications. Efforts are underway
to develop acceptance criteria for laser cut and welded struc-
tures for U.S. Navy applications.
Shipyard Laser Use around
the World
A number of shipyards are starting to implement laser pro-
cessing. As an example, Odense Lindo Steel, Meyer Werft, and
Fincantieri are all involved in implementing laser beam weld-
ing in the fabrication of ship structures. Other European yards,
such as Blohm & Voss and Vosper-Thornycroft, are involved in
laser cutting. In Japan, a major producer of high-power laser
cutting systems, a large number of shipyards have imple-
mented laser cutting.
Work at the European shipyard Meyer Werft is of special
interest. Meyer Werft is using the deep penetration charac-
teristics of the laser to alter the design of the bulkhead and
deck panels for improved productivity. Using face plates on
either side of a series of vertical webs, laser stake welds are
made through each faceplate and into the vertical webs. The
(continued)
Diagram of “sandwich panel” being fabricated by
Meyer Werft Shipyard for shipboard application.
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Chapter 9 Related Cutting Processes 219
resulting “closed-cell” design is stiffer than a conventional
plate/stiffener design and occupies less space. Also, the “flat-
ness” of the finished panels makes outfitting (installation of
flooring, insulation, wiring, and other piping) easier and
faster. The reduced space also can mean a decrease in the
overall height of the ship for the addition of an extra deck.
In the United States, there have been only a few cases in
which lasers have actually been used in shipyard applications,
although laser materials processing for shipboard applications
has been under investigation for more than twenty years. This
has been partially due to the low production rate of commer-
cial ships in the United States and in part because of the qual-
ification requirements for the U.S. Navy. Applications currently
used in United States shipyards for laser-processed materials
include cladding, welding, and cutting.
As an outcome of research accomplished by the United
States Navy Manufacturing Technology (MANTECH) pro-
gram, there have been a number of applications for laser
cladding and welding. Laser cladding for repair has been
accomplished with steel, nickel, aluminum, and cobalt-based
alloys. Procedures have been qualified for the repair of such
items as diesel cooling pump shafts, steam valve seats, aircraft
carrier catapult components, and aluminum torpedo shell
sections. In many cases, the laser process has been selected
because of low dilution and heat input, which result in a
“near-pure” deposition of material with little thermal impact
on the part. The repairs are justified because of the high cost
of replacing the parts and the long lead times required to
qualify new suppliers and receive replacement parts.
Cutting is presently the most active United States shipyard
application for lasers. Bender Shipbuilding and Repair of
Mobile, Alabama, has purchased a 6-kW CO2 laser cutting sys-
tem with a cutting table for the processing of steel, stainless
steel, and aluminum alloys. The system is part of a “first oper-
ations” that receives, cleans, primes, and cuts plates prior to
fabrication in the shipyard. The laser system can cut steel up to
32 mm thick and aluminum up to 12 mm thick. The advan-
tage of the laser has been the ability to “common line cut,”
which is not possible with plasma. The laser system can also be
used to pierce and cut openings in the plate that would oth-
erwise be drilled and manually cut as secondary processes.
Bender has already used the laser system to cut steel for its
ships and is looking ahead to other applications.
Laser Use Growing Worldwide
The use of lasers in shipyards is on the rise throughout the
world. Laser cutting is quickly replacing more traditional oxy-
fuel and plasma cutting techniques due to the cost savings and
the laser’s precision and flexibility. The advantage of laser
welding for the fabrication of ship structures also appears
promising. To take full advantage of these properties, new
designs, lasers, and processing techniques are being devel-
oped. At the same time other secondary processes, such as
heat treating, forming, and cladding, are being developed for
fabrication and repair. New specifications are being written
that will cover the implementation of lasers into ship fabrica-
tion. All of these indicate lasers will be the new tool in the fab-
rication of ships and naval structures in the years to come.
Art and article courtesy of the American Welding Society.
Review
1. Describe the use of the following processes: LBD,
LBW, and LBC.
2. How is laser light formed?
3. Other than the lasing material, what is the differ-
ence between solid state lasers and gas lasers?
4. What effect does a material’s surface have on the
laser beam?
5. Using Table 9-1, list the assist cutting gas and the
material it can be used to cut.
6. What are reactive laser assist gases called? How do
they work?
7. What type of laser beam is used for drilling? Why?
8. What is CAC-A?
9. Using Table 9-2, give the recommended procedure
for air carbon arc gouging of carbon steel, magne-
sium alloys, low alloy copper.
10. Why are some carbon arc electrodes copper-
coated?
11. What may occur if an SMA welding machine has
below minimum arc voltage for air carbon arc
gouging?
12. How can carbon arc welding be used to ensure
100% weld penetration?
13. What is washing, and how can it be used?
14. How are oxygen lance cuts usually started?
15. What unusual material can be cut with an 
oxygen lance?
16. What are the advantages of abrasive powder to the
water jet cutting stream?
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