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said incandescent light bulb is a rather
simple device its base has two metal
contacts which connect to a metal
filament the electric current's
electrons collide with the atoms in the
filament making them vibrate this energy
heats the atoms to 4000 degrees
fahrenheit at which temperature they
emit visible light the light bulb
factory has two production lines that
eventually merge one prepares the glass
bulb the other makes what's called the
mount the electrical components that go
inside it at the start of the mountain
line a machine cuts glass tubing into
pieces of specific lengths the cut tubes
land on what's called a glazing wheel
that runs them through a gas flame for
about seven seconds this heats the glass
enough to smooth the surface
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the glaze tubes now enter what's called
a flare making machine which heats each
tube until the glass is malleable then
stretches one end into a flared shape
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the next machine loads two copper lead
wires into the flare end
then it inserts a thin glass cylinder
called the exhaust tube
a trip through a series of progressively
hotter flames softens the tubes a press
then moves in to squash them encasing
the wires in glass
at the same time the machine makes a
tiny hole in the glass in between the
wires this is to later remove air from
inside the ball it'll exit via the
exhaust tube through this hole
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next the machine separates the lead
wires and forms the ends into hooks
these fasten to the filament a thin wire
coil made of tungsten a type of metal
that holds up well to heat
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the machine coats the lead wires in a
liquid form of another metal zirconium
this lengthens their life span by making
them more resistant to moisture inside
the ball
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like the tubes we've just seen the bulbs
are made of an inexpensive type of glass
called soda lime glass
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a machine stamps the top of each bulb
with the voltage the wattage and the
company logo
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opaque light bulbs are simply clear
bulbs with an inside coating of
synthetic silica a white powder
the coating machine charges the bulbs to
30 000 volts combined with just the
right amount of heat this electrical
charge makes a thin layer of powder
cling to the glass
a series of flames evaporates moisture
and bakes off any impurities
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as the two production lines merge a bulb
goes over each mount
torches then fuse the flared end of the
mound to the neck of the ball
arms move in and mold the neck to fit
inside the bulb's aluminum base
the next machine vacuums out all the air
in the bulb and replaces it with
pressurized argon gas
this inert gas will resist heat build up
helping the filament last longer
after bending the lead wires out of the
way torches melt and seal off the glass
exhaust tube locking the argon gas
inside
the bulb would now be fully functional
if connected to an electric current
but it needs a base in order to screw
into the socket of a light fixture
the base is made of aluminum
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machine inserts one of the bulb's lead
wires through the middle and solders it
in place
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it then spot welds the other wire to the
side
the result two base contacts to line up
with two socket contacts
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on their way to packaging the bulbs
undergo what's called flash testing
repeated light ups using a higher
voltage each time
this strengthens the filaments inside
making it less likely to break during
shipping
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you