Evening star., 1942-09-20
Top Anti-Aircraft Cur
In Mass Production
AT Chrys|er Plant
Bofors Weapon Turned
Out by Carloads
To Army, Navy
BY DAVID j. WILKIE,
Wide yyor1H

DETROIT, Sept. ia little more
than year ago K. T. Keller, presi-
dent Of Chrysler Corp, was asked
whether he could make Bofors 40
millimeter anti-aircraft cannon.
Mr.. Keller probably never had
examined Bofors, but he thought"
it could be made in the Chrysler
plants that formerly turned out
automobiles.
Under his direction two of the
big "Ack-Acks' were made for trial
purposes; It took something like six
weeks to assemble the pilot models.
Today these cannon, described by
Army and Navy officers as among
the most effective weapons yet de-
vised against dive bombers and
other aerial attackers, are being
shipped out of the Chrysler plants by
the carload every day.
The funnel-mouthed Bofors. orig
inally called an automatic field
gun, was in production by Bofors
in Sweden about, the time of the
Spanish-American War. AS initially
produced abroad, the assembly lob
required something like $50 hours for
each gun and, being hand finished,
each retained an individuality that
precluded an interchangeability of
parts or speed of output.
Through the resourcefulness of
our mechanics and through the ap-
pllcatlon of our experience with
automobile manufacturing" Mr..
Keller explains, I'VE have been able
10 reduce the assembly time to a
small fraction, while at the same
time greatly improving the inter-
changeabillty of the component
parts"
That sounds as though putting
together the big gun-it has a muz-
zle velocity of 1850 feet a second
and fires from 100 to 140 rounds
mlnute-Was simple manufacture
ing process. 1t was anything but
tnat, according to the engineers
VINO developed the mass production
technique.
AT the outset the original blue
prints sent from England were laid
out In the metric system and had to
be converted into the decimal
method OF measurement; moreover
many OF the dimensions were on a
nat basis, leaving no tolerance
1hls was not needed on a lob in
which each unit was hand finished
TO go to volume production pro-
gram which means, first of all. parts
lnterchangeability, the tolerances
had TO be provided for. Then came
the development of new boring. hon
ing and rlf1lng machinery for the
more delicate operations in gum
Darrell making.
Something like 300 machine tools
were required to "Americanize" the
gun including various types OF
reamers, drills, presses, honing de-
vices and many special jigs and pre-
clslon tools. Chrysler put the gun
INTO production last February: pro-
ductlon today is more than 80 times
that of the first month of output,
Chrysler is making the Bofors
Tor both the Army and the Navy. in
the same factories. For the NAVY
the weapons are built with water
cooling jackets; for the Army thev
are alr-c cooled.
The component parts OF the cam
non come to the Chrysler plants as
rough forgings, castings or stamp
lngs. They go through. hundreds of
machining operations, an idea con-
ceived by Mr.. Keller to speed up pro-
duction.
In one operation 300-pound steel
forging from which the breech ring
is made is machined down to 1O5
pounds; in another barrel sleeve
that formerly was carved out of a
solid piece of steel now is made from
piping; in still another the barrel
Is machined down by group OF
cutting tools that bite as much as
a quarter OF an inch deep as the bar
rel revolves.
The Bofors gun derives its name
from the great Bofors Co. of Sweden
which began manufacturing arms in
1884. DR.. Alfred Nobel, of peace
prize fame, and inventor of nitro
glycerin explosives, was once its
president. The Krupp Co. of Ger
many once held large interests In
Bofors' but withdrew in 1887 when
the Swedish parliament passed a
law prohibiting foreign ownership.