Evening star., 1941-02-16
Sand Mo|ds Are Key
To Performance Of
U. 5. Warp!anes
Delicate Castings Give
Cooling Power to Make
High Speeds Possible
BY JOSEPH S. EDGERTON,

y
FAIR LAWN, N. j., Feb. 10
Bigger and better sand castles are
the key to the giant new aircraft
engines which make possible the
high speed and superior per-
formance of the modern warplane.
Only the most remarkable ad-
vanceS in the science of sand
castings have made possible the
exceedingly intricate castings which
composeS the cylinder-head of the
present air-cooled aviation engine.
The power of the engine is in direct
ratio to the cooling capacity of the
cylinder head and barrel. Cooling
is accomplished by the passage of
the air. through which the airplane
flies, between deep, thin fins sur
rounding cylinder-heads and bar
rels.
This is where the sand-castle
technique comes into play. A few
years ago cast cylinder heads were
comparatively crude. They could
not be cooled efficiently and until
they were no great increase in
horsepower could be expected.
Sand Molds Are Complex.
Science turned to methods of i'm
proving the castings. The results
are apparent in the factory of the
Wright Aeronautical Corp. here at
Fair LaWn-one of five plants in the
Paterson area devoted to the pro-
duction of Wright military engines
for the United States and England.
These engines now are producing
more than 1000 horsepower, as COM
pared with quarter of that output
only few years ago.
The cylinder-heads for the 1000
horsepower engine are cast in sand
molds OF the utmost complexity and
dellcacy of detail. They are per-
haps the finest and most delicate
molds ever produced Scores of fine,
thin fins are modelled in damp sand |
supported by dozens of stiff wire
"SpineS,"
Each mold is masterpiece of the
casting art and each mold is des-
tlned Tor destruction in the process |
OF making a single casting. Four
molds are required for each cylinder
head casting-two of the very intri.
cate outer molds, with their elabo-
rate filming, and two core printes"
or interior moldS which provide
necessary cavities inside the
cylinder-head.
Four Kinds of Sand Used.
Four molds to cylinder-14 CYL
,1ders to an engine-l 900 engines
or more a month-thiS business of
Tuld1ng sand castles has become
~uslness on the grand scale indeed.
-Four varieties of sand are thor
oughly combined to provide the
proper mixture for the foundry
Eere. Whole trainloads of sand are
required, and their delivery is blr
the beginning of complex and.
Tor the layman, fascinating proc
eSs. Formerly, sand was conveyed
to the molders in wheelbarrows.
Here 1t is moved by hoppers and
conVeyors right to the work benches.
The molder does not even have to
turn around to take sand from a
barrow-it is delivered right under
his hands.
1he molds are made up in boxes,
each a quarter the size of an av-
erage desk top. A brass form drilled
to take the wire stiffeners for the
nm molds is the basis for the molds
Tor the halves of the exterior cyI-
1nder-head form. Into this box.
over the brass form. the molder
dumps his sand, slightly moistened,
and begins to shape the mold, for
all the world like a child building
an unusually elaborate sand castle !
on the beach.
SmOOthed to Paper Finish.
No child, however, ever dreamed
of sand castle so intricate and
beautiful as the molds which take
form under the skilled hands of
these highly trained specialists. The |
mold completed in moist sand and
smoothed to almost paper finish. the |
mold goes through processes of
drying and baking, during which |
open flames are played over its sur
faces and into the most remote
fin cavities. The sand takes on
deep shades ranging from yellow
through the darkest red browns, and
SCOT covers the surfaces of the
cavities.
Thoroughly dried and heat hard
ened, the four molds are assem-
bled into huge block of sand with |
large, funnel-shaped opening.
into which flood of Kissing, molten
metal is poured until the form
overf1ows. With iron bars and pick
axes, it is broken away from the
casting. Chunks of the mold are
broken up with sledges, and the
bracing wires which can be picked |
up easily are thrown into the bins. |
Ihose which do not come clear, to- |
gether with the broken fragments
of the mold, by now reduced almost
to the original loose sand. are
pushed through holes in the floor
onto a conveyor belt, which carries
this expensive, laboriously created
debris out to the dumps. Even the
sand has become useless, in so far
as the foundry is concerned. It can
not be reclaimed and used again.
Curtiss- Wright now is building a
10000 = square foot magnesium
foundry adjacent to the present
foundry. Soon to be finished, the
magnesium foundry is to be one of
the finest of its kind in a country
which has had few facilities of the