NARRATOR: It arcs, explodes
and blisters steel. It's used to make
50% of all products, and it puts the power to build
a skyscraper in a man's hands. By friction or robot, even
under water, these are the tools that the world
can't live without. Now Welding on "Modern Marvels." Las Vegas, Nevada. Perhaps nowhere
else in the world does the old come
down as spectacularly and the new rise up as quickly. Right now you're in the east
wing of the new Palazzo Hotel. We're on the 38th floor
area, laying deck. NARRATOR: The Palazzo hotel
will be the central hub of the world's largest resort,
hotel and casino complex. And without the power of
welding, it couldn't be built. Armed with high power
welding guns and with nothing more than a safety harness
between them and the ground below, these ironworkers
will weld a quantity of steel nearly equal to the amount
in the Brooklyn Bridge, Statue of Liberty and Empire
State Building combined. There's just shy of
70,000 tons of [inaudible].. NARRATOR: Adrenaline runs
high for welders working at such heights, and with
so much electricity in use, the dangers are real. This particular machine
runs on 483 phase. It's fed with 200 amps. At 480, if you make a mistake,
you're not here tomorrow. It's almost instantaneous death. NARRATOR: By definition, welding
joins two separate pieces of material through high energy. No other joining method forms a
more direct and powerful bond. All the other methods,
whether it's rivets, whether it's bolts, even if
it's glues and adhesives, you wind up putting
in extra material in order to make the connection. In the case of
welding connections, bring the two pieces together,
put a weld in between. It's a very efficient
way of joining material. NARRATOR: But efficiency
is only half the story. Because welding creates a
bond along a seam or joint, it is nearly always stronger
than the base metals used to form it. The tensile strength
of the welded material itself is actually greater than
the material you're welding. A good weld, the material itself
will tear before the weld will tear. NARRATOR: The source
of this strength is more than just surface
deep and goes right down to the steel's very atoms. Every atom within
a beam possesses electrons that encircle it
in what is called an electron cloud. When a welder
applies intense heat, the atoms are slammed
together so forcefully that they begin to share a
single, united electron cloud. Now locked as one, these new
molecules are more powerful together than separate. For many centuries, the only
way to make these welded bonds was with furnace and
hammer, a process now known as forge welding. With forge welding,
two pieces of material are put lapped over
each other, heated not to the point of melting
but until they're hot, and then hammered together. That hammering together
of the two metals will achieve the same
metallic bonds that today we form with an electric arc. NARRATOR: Today, electricity
has replaced the brute force of the forger's hammer
to construct our world from the car you drive to the
plane you fly and everywhere in between. The most common method is known
as electric arc welding, which is based on principles
first discovered at the turn of the 19th century. Those principles revealed that
electric current will jump the gap between two
nearby metal conductors to form a completed
electrical circuit. This jump, known
as an electric arc, generates a spark-like discharge
that is both extremely bright and intensely hot. The arc is estimated to be
between 6,000 and 8,000 degrees Fahrenheit. That's the same
temperature as the sun. Steel melts in and around 3,000
degrees, so this 6,000 to 8,000 degree arc is more than
ample heat to melt the steel that we're joining. NARRATOR: By the
1890s, engineers had harnessed this intense,
newfound energy to create the first electric arc welds. A work lead or ground was
attached to one corner of the metal to be welded. Electric current then
flowed from a generator through a long conductive metal
stick known as an electrode. As the stick neared
the grounded metal, an electric arc was formed,
causing heat to melt the metal. The apparatus was crude but the
basics were sound and are now reflected in the
simplest arc welding form in use today,
stick welding. The basics of the process are,
you have an electrode holder, you have a cable that runs
back to the machine to pick up the welding current, and
you place the bare end of the electrode in the
holder, and it picks up electrical contact there,
conducts current down to the end of the
electrode, which is bare. The technique is touching the
electorate against the work and then moving it far enough
away to establish an arc but not so far it goes out. And if you leave it
too close, it'll stick. You pull away too
far, it'll go out, so the trick is to get
your bounce where it's just about right. NARRATOR: When the arc is struck
and positioned near the metal pieces, the intense heat
causes both the electrode and the metal along the
seam to melt together into what is called the puddle. Until it hardens,
this molten puddle must be protected even from
the very air that we breathe. The air we breathe is about
80% nitrogen and about 19% oxygen. It's really good
for breathing but it's not good for liquid metal. And just like we dissolve
sugar in hot coffee, these gases dissolve
in liquid metal. When the metal solidifies,
the gas percolates out and that make holes in the weld. NARRATOR: The dangerous result
could be a weak, even brittle weld, so to shield the
puddle, a chemical coating is applied to the electrode. As it melts under
the heat of the arc, this chemical coating
dissolves into shielding gases that envelop and protect the
weld, keeping it free of air. This is known as shielded
metal arc welding, and as the technology
evolved, the coating took on even greater
significance. The chemical coating
has three functions. Some of the coating
forms shielding gases at the heat of the
arc that protect the weld from the atmosphere,
some of the chemicals at the heat of that arc form
a liquid slag which protects the weld as the shielding
gases move along, and some of the elements
are alloyed into the deposit to make a high strength deposit. So three things
happened while you're moving this arc along the work. NARRATOR: When the weld
is complete and is cooled, the slag is chipped
away to reveal the trail of welded
metal known as the bead. Getting the proper
length, depth and form of the puddle along the bead
takes years of practice. There's so many
variables when you weld. There's very few times that
two things you weld together are the same. Either the metal
changes, the thickness of metal, the environment
you're in, the conditions the metal is used for-- there's
just so many things change that you have to know a lot of
different things about welding. NARRATOR: Complicating matters
are the safety requirements, beginning with a welder's mask. Just as staring into the
sun can damage your eyes, so too can an electric arc. Therefore, protection
is crucial. When you first flip
it down, it's dark. You can't see anything, but
you quickly get comfortable with it. Once you strike the arc,
it's like a big flashlight. You can see what you're doing. NARRATOR: Although electric
arc welding was first discovered in the 1800s, its
acceptance was slow in coming. Anything new, they fight. It wasn't thoroughly
accepted so it took time to make the transition
into the welding process. NARRATOR: No company was
more influential in changing the tide than Lincoln Electric
Company of Cleveland, Ohio. Today, Lincoln Electric is the
largest manufacturer of welding equipment and
consumables in the world. That success is rooted
in Lincoln's commitment to proving the
viability of welding, even in the face of
constant doubters. And no industry was initially
more skeptical than the biggest one of all, building
construction, where rivets were king
well into the 1940s. Rivets were intuitive. If you think about it,
putting in something with a head on either
side, that makes sense. Welding had some
mystery about it. NARRATOR: But riveting was
also extremely difficult work. It required fabricators to
hole-punch the steel beams. Then a team of workers
aligned those holes to their exact counterpart. Rivets were heated in a
central oven then hurled to the proper joint. He would hit the rivets,
and once they got heated, he would throw them to the
person who was actually standing at the point
waiting for the first rivet. So you had a pitcher, a catcher
with a set of tongs who would slide it into the hole, and then
you had a guy with a bucket, and then you had a riveter. And the riveter would round
the head on the opposite side. NARRATOR: Significantly, rivets
limited the design options for architects and
building engineers. A lot of very famous
and beautiful work is done with rivets,
but basically, you're building a box with a design
to the inside of the box. You can only carry so much
shear on that connection. NARRATOR: In 1928,
Lincoln Electric joined with a local
architectural firm to erect the first commercial
building wholly constructed from arc-welded steel. In the upper Carnegie Building,
the typical dense network of riveted steel was replaced by
a series of continuously welded beams that ran the entire length
and height of the building. Not only did welding
free up space, but these continuous beams
carried even greater loads and stresses than their
riveted counterparts. Connection's always the
weak point in a structure. Connecting things together
is always a challenge, but welding changed all that. Literally, if you could get the
material in the configuration you wanted it, there was
a way to weld it together. NARRATOR: Today's skyscrapers
come in many shapes and sizes in large part because continuous
beams can be fabricated and welded into curves
and unique angles. To construct these
beams, welders will make 30 to 40 passes
on the crucial joints, using Lincoln Electric's latest
flux-core welding technology. Here, the traditional
stick electrode has been replaced by wire on
a roll that feeds directly into the welder's gun. The chemical flux that
protects the weld from the air is now contained
within the wire itself and melts just as before. There's approximately
90 tons of weld wire that will be used and consumed
in this project alone. That's somewhere around 180
million inches or 2,800 miles of weld wire. You could stretch a single
wire from LA to New York and have leftover. NARRATOR: On the
largest beams, which can weigh as much as 900
pounds per linear foot, a team of welders can work
on a single weld for hours. The columns that we're
looking at right now are basically supporting the
entire east wing of this tower. Originally, these
pieces were so long, the capacity of the cranes would
not pick them up and set them, so we had to cut them down, make
them lighter so the crane could set them. And the engineers
wouldn't allow us to make that a bolt and splice. It had to become
a welded splice. It's about a 30-hour weld. I believe we had two guys
working on that simultaneously for 30 hours of welding. Welding really enabled
the architect, the engineer, to dream bigger dreams,
make bigger bridges and make taller
skyscrapers, and to do so in a reliable and
dependable way. NARRATOR: But at
the end of the day, those big dreams are only as
solid as the ironworkers who weld them together. We're not presidents. We don't get
monuments built to us, but when you look
across the skyline, ironworkers have changed
the way that looks. NARRATOR: But electric
arcs aren't the only way to make a weld. In fact, others
are a real blast. Pennsylvania's
Allegheny mountains, birthplace of American steel. Here in the hillsides that
surround historic mill towns, the most powerful
welding process of all occurs more than half
a mile underground. Fire in the hole. [explosion] NARRATOR: It's called
explosion welding, and with a force measured
in millions of pounds per square inch, explosion
welding does what no other welding method can-- join nearly every kind of metal
together, no matter the type or composition. Explosion welding allows
highly similar metals such as aluminum, carbon steel,
alloy steel, stainless steel, alloys of copper-- all can be welded
to one another. NARRATOR: The result, a single
welded piece known as clad that combines the best
characteristics of each metal involved. Wherever there is high heat,
intense pressure or corrosive liquids and gases,
clad is probably there. It could be a column, it
could be a heat exchanger, it could be a horizontal
tank, but when you see a chemical complex
or an oil refinery, there will be a lot of
clad metal in there. NARRATOR: To create an explosion
weld, two large pieces of metal are stacked atop one
another, then covered with a high-powered explosive. When detonated, the downward
force of the explosion welds the two pieces together
through a combination of intense force and
remarkable physics. What you can see here,
and it's very clear, you have two
different materials. Stainless steel is a
darker gray, a lighter gray for the carbon
steel material. The detonation was
initiated at this point and you can see the
deformation from our initiator. That starts the explosion
and the explosion rolls across the entire
top surface of the plate, zipping the two together. NARRATOR: No one would have ever
thought such a violent process could be controlled
and mastered had it not been for the devastation
and havoc of World War I and later WWII. The origin of
explosion welding was first observed during
the First World War when shrapnel may have
stuck to armament. It wasn't just stuck but
it was actually welded. NARRATOR: There was only
one possible explanation, the explosive force these
metal pieces had endured. It was an observed
phenomenon that was later duplicated in the laboratories
and practiced commercially. NARRATOR: Today, Dynamics
Materials Corporation is a world leader in
explosion welding technology. Here, the decades
old discoveries from the battlefield have
been refined into an exacting science. The explosion welding process
begins as soon as the two metal plates arrive at DMC's main
plant outside of Pittsburgh, Pennsylvania. To maximize the welding
course of the explosion, the surfaces of each plate
are ground as uniformly flat as possible, a process that
also removes any rust, oxides and other surface flaws. They're then ready to be
assembled into the pack, which locks the plates into
position for the explosion. To build a pack, the stronger
and thicker of the two plates is laid face up. From now on, this plate will
be identified as the backer. Small metal spacers
of equal height then tacked onto the surface of
the backer in a uniform grid. These spacers will
maintain a set gap between the backer
and the second plate which is placed on top. The second plate is
thinner than the backer and is called the cladder. The stand-off gap between
the backer and cladder is less than an inch in height,
yet without it, the explosion weld would be impossible. In the final stage of
assembling the pack, a folding wooden
frame is constructed along the edges of the cladder. When this frame
is later unfolded inside the underground
explosion chamber, it serves as the bed for
the explosive powder that is poured on top. The three essential variables
of an explosion weld are first, the stand-off gap. The spacing between
the two metals needs to be very tightly
controlled to ensure the highest quality weld. The second two parameters
deal with the explosive. One is the velocity
of the explosive, the speed at which it
burns, and the height of the bed or the quantity
of explosive which is evenly spread on the top plate. NARRATOR: The explosive
powder is a proprietary blend of common and unique
explosive chemicals. The amount and exact
formulation is always matched to the types of metal involved. Once the pack is set,
everyone evacuates the chamber except the blaster
in charge, who remains to wire the detonator. He will be the last
to leave the chamber. After all personnel
are accounted for, the blaster connects
his initiator switch to the detonator wires
and fires the explosion. Fire in the hole. NARRATOR: The explosion
is detonated from one edge of the cladder and moves
across the upper level of the pack at a uniform speed. This explosive
front progressively drives the cladder plate
downward toward the backer at the slight collusion angle
caused by the stand-off gap. Forward of the collision
point, air is forced out of the gap at high velocity. All oxides and impurities are
expelled, rendering the plate surfaces metallurgically
pure and ideal for a weld. As the backer and
cladder collide, the weld is created
nearly instantaneously across the entire
surface of the plate. Because of the intense dust
created by the explosion, workers can't retrieve the newly
formed clad from the explosion chamber for more than 18 hours. Not surprisingly, the
power of the explosion can cause significant
deformation to the newly formed clad. Therefore, upon its return
to DMC central processing facility, the clad undergoes
a final series of corrections. These include heating the
clad in an oven that causes the metals to soften slightly. This relieves stress from the
blunt force of the explosion's impact. Any bowing or misshapen
curves are flattened out by either a three million pound
press, or for thinner clads, by a series of rollers
known as levelers. Finally, before the
material is shipped, stringent testing is conducted
to ensure a solid weld between the two plates. There's a lot of testing
because generally, these metals will go into a very
high pressure vessel. The stakes are extremely
high if there's a failure, ao the owners of big plants and
chemical manufacturing and oil refineries are extremely
concerned that their materials are what they ordered
and specified. There's really no
room for error. NARRATOR: Once the
material has been proven to meet exacting specs,
it's ready to be shipped to the customer. But explosion welding isn't
the only adventurous business, and may look downright tame
compared to welding 325 feet below the ocean's surface. It's a rule that
defines common sense. Don't mix water
with electricity. It can kill you. But there is a rare
breed of experts who dare to swim
against convention and perform a job that most
consider downright crazy. Underwater diver welders thrive
on the dangers of the deep where visibility can be zero
and deadly hazards the norm. Why? To perform the perfect weld. You're under water and
playing with electricity. It doesn't seem like
a good combination but it works quite well. NARRATOR: Over
the last 30 years, the ocean depths have become
vast job sites for the energy and communication industries. This encompasses everything
from pipelines to platforms to subsea wells to inspection,
repair and maintenance. We're working in water
depths up to 10,000 feet. NARRATOR: Global
Industries is a leader in offshore construction,
engineering and support for the oil and gas
industries around the world, and to meet this
constant demand, Global Industries requires
their welding teams to undergo years of specialized
training for all types of offshore environments. We're here at our research
and development training center here in New Iberia, Louisiana. We're dressing out our
dive now to getting ready to get into the tank
and do some training, do some welding. NARRATOR: There are two basic
forms of underwater welding, wet welding and dry welding. Wet welds are the most common
and can be shielded metal arc or stick welds made by
a fully submerged diver welder in a wetsuit. The electrode is waterproof and
inserted into an electrically charged rubber-encased stinger. Once struck, the electric
arc burns just as if it were on dry land since
water is equally conductive. Likewise, the electrode's
unique waterproof coating shields the weld from
water contamination. But in case you're
wondering, his rubber gloves are the only things that
stand between the diver welder and electric shock. You have a hole
in that glove, then you grab a hold of
that live stinger, and that will give
you a real good one and you'll taste your
fillings in your mouth. NARRATOR: Fortunately,
the odds of a fatal shock are slim because the
welding equipment operates on DC current, which is far less
dangerous than the ordinary AC current found in a typical home. Comm check, comm check. NARRATOR: To get the
diver welder fully suited, two other diver welders
act as his tenders, checking and testing every
piece of equipment, including the helmet. Not only does the helmet
provide air for the diver welder to breathe, it also serves
as a full welding mask, protecting his eyes from
the intense arclight. Right here we have the
lens plate, the face lens that a diver will flip down when
he's ready to start welding. He'll flip it up when
he's finished welding and take a look and
see what he's doing. NARRATOR: After the diver
welder is suited up, he carefully enters the
water and makes his way to the bottom of the tank. From the moment he
puts on his helmet, the diver welder is in constant
communication with the control room via audio links
and a video feed. Comm check, one, two, three. How do you got me, John? JOHN (VOICEOVER):
Four, five, six. Loud and clear. All right, set up the weld. Roger, setting up. NARRATOR: The
trainee must not only learn to strike and
maintain an arc, but he must also be able
to connect and reset all of his equipment,
including the electrode. Once in the water, the electrode
is inserted into the stinger, which is termed cold because
the control room has not yet turned on the electricity. When the diver is ready to weld,
he requests that the current be turned on. [inaudible]. Make it hot. Roger. Making it hot. NARRATOR: Like every
surface welder, the diver welder must be
a master of concentration and stability. You're going to have a lot
of things that can interfere with what you're doing
when you're welding. Just the surge of the
ocean can push you around. Some divers like to actually
put their hands up, hold the rod itself, because it gives
you a lot of feel on it. If you just have the
rod way back here from where you're working,
you don't have the feel that you need. NARRATOR: Even fish can become
distracting and potentially dangerous obstacles. Barracuda like to watch. It's a giant fish. It looks like a torpedo
with nasty teeth that stick out everywhere, and
they like just kind of hover over your shoulder to see what
you're doing all the time. And you're just kind
of like, what's-- ah! But they're doing
their own thing. NARRATOR: But sometimes a
job requires a diver welder to go to extreme depths and stay
in that environment for days, even weeks. This is called saturation diving
and requires serious courage. It may also require the highly
sophisticated technologies of dry underwater welding. The difference between wet
and dry underwater welding, the dry underwater weld
will require a habitat. A habitat is lowered
down and put in place on the member on the pipeline
that's going to be repaired. Once it's installed,
they seal it and then they actually
put the air down to it and pump all the
water out of it. This allows that piece
to be basically dry now, and so the divers can go
down, and they'll actually climb up inside the habitat,
remove their helmets and actually be able
to go to work and weld that particular item in the dry. NARRATOR: Dry
underwater diver welders work in pairs and in six
to eight hour shifts. When done, they return to
the surface in a diving bell, then enter a second habitat
maintained aboard ship. Within these ownership
habitats, they will eat, sleep, and relax
before returning to the ocean floor. Both the diving bell
and on ship habitat maintain the same pressure
as if the divers were still 1,000 feet under water. This is the only efficient and
practical way for their bodies to remain adjusted to
such extreme pressures. Otherwise, the diver welders
may experience the bends and other physical
perils, even death. To prepare diver welders
for these conditions, Global Industries has built
an unparalleled underwater simulator. This facility that you
see behind me right here, It's really the only one of
its kind in the United States. We call this the dry pot. We can carry out dry welding
scenarios down to 1,000 feet. NARRATOR: A hyperbaric chamber
simulates the high pressures the human body must endure when
working at great ocean depths. Akin to being an astronaut, the
trainee will spend more than a week living in this
simulated environment, and conditions are tight. It's very, very
cramped inside there. There's a place for
everything to go and you have to be sure that
you put everything in its place before you go in and
start doing things, because there are a lot of
things that can bite you in there. NARRATOR: Unlike the wet
welder, the dry welder can perform more than stick
welds in his cramped habitat. I'm standing right in
front of the entrance to the dry pot hatch. Royce is doing gas
tungsten arc welding. It's also known as TIG welding,
which is our word for Tungsten Inert Gas. NARRATOR: Once his
training is finished, the trainee enters this
decompression chamber to slowly acclimate his body
back to the normal atmosphere. But while even these
adrenaline junkies need to rest once in a
while, some welders never take a break. Of course, they're robots. Welding, the heart and
soul of making a car, and for major
automobile manufacturers like General Motors, no
process is more vital or more automated. When I first started
with General Motors, there weren't any robots in
the body shop I worked in. Two years later,
there were 40 of them. In the body shop
we're standing in now, there's approximately
1,200 robots. Over a third of them,
480-some, are welding robots. NARRATOR: Here at GM's
Lake Orion assembly plant, more than 16,000 cars roll
off the lines every month. By the time each car
is fully assembled, it will contain
thousands of welds. On this structure
as it sits right here, there's approximately
3,800 welds. Once the outer
structure goes down, there will be approximately
1,200 more welds added to it for
approximately 5,000 welds overall on the vehicle. NARRATOR: Nearly all
those welds are completed by robotic welding systems
which load, position and weld more than 240 component parts. Most of the robots
that are used for welding are actually used
for spot welding, and probably 60% of the
welding robots that are out there are actually
spot welding robots. NARRATOR: Unlike arc welding,
spot welding does not create a bead, nor is it
designed for heavy steel items like beams. Instead, spot welds
bond thin metal sheets as in car doors or hoods. Energy is focused
to a single spot where two electrodes make direct
contact with the metal sheets to be joined. The electrodes
are made of copper because it has low
electrical resistance and high thermal conductivity. This means it can deliver
some serious juice. This particular unit is a
pneumatic operated spot welding system. It's got a 75 kVA
transformer back here. The electrodes up here
are all water-cooled. This particular
setup here probably runs about 10,000 to 12,000
amps through these electrodes right here. It's not uncommon to see
40,000, 50,000 amps run through the electrodes. NARRATOR: Given that most houses
run on less than 200 amps, that's a lot of power, but
it's not the only factor in a reliable spot weld. You need pressure. When the two electrodes
come together, they pinch the two
metal sheets at the spot and cause a small
indentation in both. Electric current
then begins to pass from one electrode to the other
through this spot in the sheet metal. As it does so, the current
that flowed so smoothly through the copper now
encounters resistance in the less conductive
metal pieces. This resistance results
in heat and the metal begins to melt causing
a molten nugget to form. When the molten nugget
cools and coalesces, it locks the two
metal sheets together. The electrodes then release
the pinxh point and move on. A robot can make a
series of spot welds in a relatively
short period of time. For a man, it's a heavier task. A typical spot welding
gun might weigh anywhere from 100 pounds to 200 pounds. That's a lot of physical labor
to move a spot welding gun, and so a robot that's designed
to handle that kind of weight is an ideal setup, because the
robot can just handle the spot welding gun and consistently
put it in the same place every time. NARRATOR: Factor in the
sheer number of spot welds required to assemble
a car, and robots make an incredibly practical
solution for car manufacturers. And advances in
recent technology allow robots to reach
further, work closer together and execute a greater variety
of welds than ever before. The robot can pretty much
weld at the same speed as a man. Where the payoff is is that
a robot is always welding. A man has to weld, and then lift
his hood up and adjust the part and put the hood back down and
reweld again, Where the robot's just going to weld, weld, weld. It might have an 85% arc time
compared to a manual of 20%. It took a man
about three hours to make this particular product. Now that the robot's
welding it, it takes essentially
about a half an hour to weld the entire part. NARRATOR: But today, robots
aren't just spot welders. Here at Robot Works, a leader
in robot system integration, robots execute nearly
every form of welding, and often in surprising ways. This system has the capability
of running at about 30 to 40 inches per minute of weld. This system is unique in that
there's two technologies that are actually integrated into
it, one called touch sensing, another called seam tracking. What touch sensing
allows the robot to do is actually find the seam. It would come down, sense that
it has touched the part in one specific spot, record that
data, save that positional data. It would then come up,
sense the next spot doing the same process,
and at that point in time, the robot would know
from the trigonometry where that seam starts. There is another technology
called seam tracking. What that allows you to do
is once the robot has found the seam, it actually allows the
robot to stay within the seam throughout the
course of the weld. NARRATOR: But even
as robots become more sophisticated
and commonplace, they will still require HMI,
Human-Machine Interface. After all, someone still
needs to program them, and he or she
better know welding. For the programmer, we
always suggest to take a guy that's a good welder, because
he's going to know like if he hears an arc and it's not right,
he'll know that it might be because of the shielding gas, or
the stick-out the robot's using because he just knows welding. But a guy that
doesn't know welding might think it's because of the
robot controller or something to do with the robot. Somebody that
understands the process is the best kind of a
robot operator programmer. NARRATOR: Think
robots are innovative? Well, you haven't
seen, or should we say, you haven't
heard, anything yet. Say welding and you
immediately think iron, steel, metal on metal. But today you can weld just
about anything, including plastic. Plastic toys, plastic packaging
and lots of household items are welded together by a process
known as friction welding. Friction welding
comes in many forms. It all work
essentially the same. They generate heat
through mechanical action like the high speed rubbing
of two sticks together. With plastics, the
best friction welds are made through
the power of sound. It's called ultrasonics. Ultrasonics utilizes the high
intensity acoustic energy that occurs in frequencies
beyond human hearing. The sound waves cause
the plastic pieces to literally vibrate against
one another at high intensities. At that interface, heat is
generated and the two pieces fuse together. It happens so fast that
the naked eye can't see it. People don't realize
the amount of power that is available in sound waves
if the sound waves are focused properly, and these materials
are vibrating, in many cases, 20,000 times per second,
40,000 times per second. That frictional
heat is so intense that the plastic welds within
a fraction of a second. NARRATOR: In 1964,
Roberts Soloff received the first ever patent
for ultrasonic plastic welding. Today his company,
Sonics & Materials, builds the technology that
welds everything from toothpaste tubes to coffee
makers to simple toys. At their headquarters
in Newtown, Connecticut, ultrasonic welding
machines are manufactured to precise specifications,
or else the welds wouldn't be perfect. There are four main parts in
an ultrasonic welder, a power supply and three components
known as the ultrasonic stack. This is the ultrasonic stack
for the ultrasonic welding press, which is comprised
of the ultrasonic converter, the booster and the
ultrasonic horn. NARRATOR: The power supply
takes standard 60 hertz power and pumps it up to 20,000
hertz of acoustic energy. This acoustic energy causes
coin-sized ceramic disks within the converter to
physically expand and contract, creating 20,000 mechanical
vibrations per second. These vibrations are then
focused to the plastic parts, first through the booster
then through the horn, which delivers the vibrations
directly onto the plastic parts to be welded. Although sparks don't fly
during ultrasonic welding, it still gets the job done. This happens to be
a two-piece whistle. So we take the two
pieces of plastic. We put them in a lower fixture. The fixture is made
to the application, to the piece of
plastic, and then we have a very basic,
flat-faced ultrasonic horn because the part is flat. There's no contours to the part. So that quickly, we just welded
the two pieces of plastic together in 0.24 seconds. What I'm to do is
take a screwdriver and break the plastic apart
right at the weld area. And in turn, this will show
the molten white plastic where it bonded to the red plastic. NARRATOR: And think ultrasonic
for the hermetic seal on clear plastic packaging-- you know, the plastic you
can never quite get open? We have these PVC clamshells
or tamperproof clamshells so that the product can't
be easily removed from it or put in a pocket. Ultrasonics is commonly used
to seal these clam shells. And now we have
ultrasonically welded the edge of the clamshell. NARRATOR: While ultrasonics
occurs in the wink of an eye, another form of friction welding
will keep your head spinning. Spin welding is rotary
friction under pressure, which generates heat in the joint
area to melt the plastic and fuse the parts together. NARRATOR: A typical
insulated coffee mug is spin welded from two parts. A suction device grabs
hold of the inner shell and rotates as it descends
into the outer shell. The collision of the
stationary and rotating pieces generates heat, causing
the plastics to soften. When a braking system
stops the rotation, the softened plastic
seams of the two shells fuse as they cool. The result? A perfect hermetic seal. So from ordinary household
items to structures of extraordinary
heights and depths, welding plays a crucial
role in everyday life by simply joining
the world together.
