The Washington times., 1916-12-21
DESCRIBES PROCESS
OF MAKING TIRES
Writer Corrects Many Misap-
= 'prehenslons About How
Rubber Is Employed.
ny n. J. FIREsTONE.

President Firestone Tire Company.
Rubber Is the foundation stock for
tires and tubes. Tires are not all
rubber. II they were we would not
be able to pay for them. Neither
would they give the splendid wear
ing value that they do under the pres
emit system of manufacture.
Rubber r. imported from Brazil,
and the highest quality comes from
the native trees and IL usually spoken
OF as Para rubber. Para In a seaport
of Brasil. The rubber countr, Is
many miles distant from Para, up the
Amazon Valley. Rubber Is n sap, or
juice, from a forest tree, and Is taken
out in much the same manner as SUI
gar sap.
There is a supply of natural rubber
In parts of Africa and Mexico. but
these, do not come up to the upper
Amazon Valley standard. The lower
Amazon Valley rubber Is also a
cheaper grade.
Two Glasses OF Rubber.
The more difficult II is to get the
rubber trees the better the supply
seems to be. Even before the world
Began TO take note OF the fact that
tires would eventually create scar.
city of rubber an effort to supply the
market was started and rubber tree
plantations were set out. This makes
two classes OF rubber, commonly
spoken OF as the native rubber and
plantation rubber. There are large
rubber plantations In Ceylon and the
Malay states. Tho quality OF planta-
ton rubber depends largely upon the
source from which the trees were I'm
ported. y
Rubber comes to America In varied
grades. IL comes usually In what is
called q biscuit. This biscuit In FORM
ed by rolling up the rubber on a
stick. 30 that a native can grab ooth
ends of the stick and carry the rub
Der out of the forest. when the stick
IL removed tho. chunk OF lump OF
raw rubber is left. The rubber COM
ing from plantations In not In the bis
cult form. II usually comes In square
chunks. such as may be conveniently
sacked In barrels or boxes. Any large
tire factory has thousands upon
thousands OF pounds OF this rubber
on hand.
Treatment OF Crude Rubber.
Until one visits a tire factory he
usually has n hazy sort OF notion that
the crude rubber IL dumped into
large melting pot and boiled. But lie
Ia entirely wrong, Crude rubber. as
IL In received at our factory. contains
more or less dirt. usually In the shape
OF sand. dried leaves and uvigs.
These foreign substances are re-
moved by washing the gum. which Ia
soaked In warm water and taken into
ararkaE In this
machine the crude rubber In masti-
Gated and subjected to a continual
row OF water, washing away most OF
the foreign substances. The work OF
completing the rerioysf Of foreign
matter L. carried on In washer.
The pure gum In nnaily run through u
rolling machine aud spread out IN
sheets on Naen. These sheets must
be dried three or four weeks. The
next step l. mixing the crude rubber
with compromising ingredients,
The chemist In the mixing room
weighs out the ingredients to the
fractional part OF an ounce, In the
work rooms the entire mass IL worked
up upon rollers until v becomes
plastic whole.
Rubberisiak Cloth.
Rubberizing the cloth which goes
into tires Is done BY means OF a fric'
tioninf machine, which grlnds the
plastic rubber into the fabric at high
pressure and impregnates II thorough
~ with the gum. The fabric for the
breaker strips and canvas plies Is
first held at great heat. In order To
be thoroughly dry. Then IL II ready
TO be wound into the cslenders, which
"friction" the rubber into the fabric.
There are three huge rolls on this
frictioning machine, the middle re-
volving at high speed and the lower
at low speed, BY the difference In
the speed OF the rolls the rubber, II
thoroughly worked into the cloth,
which winds on one roll as the rub
Der revolyes on the drum opposite
Castings for automobile tires are built
up around molds formed like a wheel.
strips OF the heavily rubberlzed can
vas OF varying lengths, according TO
the circumference OF the tire 10 he
built. form the first layer In the
building up OF a shoe.
Worked Around Mold.
These layers have been sewed so
that they form continuous piece
and then are worked around the
mold. Around this inner layer go, the
various plies OF canvas, until the
breaker strip Is Inserted Plies or
rubber are added for the tread, until
the whole is built up In the form that
a Is designed to take.
This tire. mold and all, Is carried
away to he weighed, because IL mus.
come up TO certain standard. This
process, so briefly described, Is one
OF the most important OF all in tire
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