Evening star., 1924-11-16
EXPERIENCE ENDS
. 0LD-T|ME THEORY
Metallurgist Discusses Crys
talIization and Breakage
of Motor Car Parts.

Crystallization and breakage, for
merly given as the cause for the fall.
ure of a part of motor car after E
long period of service, has becom,
one of the exploded theories of TIL
past Studies which have destroyed
the old "crystallization" theory hav.
also pointed the way to even create
dependability in highly stressed part
Of the present-day car. according t.
J.. a. Danse, metallurgist of tn
Cadillac Motor Car Co.
Mr.. DanSe explains that in ad
Nanced engineering circles the mys
terious something commonly callet
capitalization and breakage has beer
analyZed just as medical men analyz.
disease and isolate its germs ant
that it is In reality fatigue" break
age, due to impurity in the metal
some one other definite defect whic'
can now be exposed by known labora
tory and physical tests.
Seen As Crystalline Mass.
'As metals are naturally crystal.
line in structure states Mr.. Danss
cit is evident that breakage in serv
Ice is not due to crystallization. TIL
metal is crystalline mass from tn
time 1t is fir-t melted and poured
When it soliditles after melting an
pouring it assumes the cryStallin
character. the same as water solid
fes to snow. frost or ice crystals.
Researches in metallurgy shov
that where a motor car part fails l.
service the principal cause is nc
mysterious at all. 1t is usually jus
plain dirt. 1t is impurity so micro
scopically fine that without the mos
conscientious examination it defie
detection.
The method of determining tn,
cleanliness of metal is really Yer,
simple. 1t is merely process o.
taking infinite pains-accuracy of eX-
animation and analysis to a degree
formerly unknown even in the best of
laboratories
Here at our plant every lot of meta
intended for use in highly stressed part
Tor the car must undergo the most thor
ough microscopical examination
The sample to be examined is first
polished to a degree of Smoothness
seldom seen in commercial products
Stnoothness in highly polished plate
glass or in a piece of silverware Is
crude compared to the smoothness
REQUIRED in tho testing laboratory.
Take silver spoon, for example
II YOU are invited out to dinner to-
night and have been lucky in your
invitation, maybe there will be a rea'
silver spoon at your place, newly pol
1Shed by the best Good Housekeep ping
methods. To your eye it looks per
fectly smooth. AS it passes your lips
they also record perfect smoothness
That surface under a powerful mi
Croscope would have rutS and fur
rows, and a plated spoon in a quick
lunchroom, under this same micro
scope, would plainly show mountains
and valleys.
When we prepare this sample for
examination we must make 1t even
micSoscopically smooth. Five hours
is spent in polishing a half-inch
square of surface.
This surface is then examined un-
der glass magnifying to 100 diam
eters-a task for a busy 90 minutes.
One might examine 1t in Is minutes,
but he would have to slight some
areas of the surface, which might
contain dirt inclusions.
Metal Is Next Photographed.
after a thorough visual micro
scopic examination the metal is pho
tographed with camera which mag
nifies from 100 to 1000 diameters, and
suspected areas are more closely
studied.
The structure must be fine in or
der to have the strength which the
work to be done by the part requires,
so we must watch for impurities
which would lessen that strength.
Sometimes we have to follow a
piece Of metal all the way back to
the steel mill, where it was first
poured into ingots, and suggest
changes in methods there in order to
bring 1t up to the required standard.
This original inspection is just a
beginning. That lot of metal is fol-
lowed all through the manufacturing
process. AT every stage samples are
brought to the laboratory and re-eX-
amined. Every day connecting rods,
for instance, are taken from stock,
cut open and examined just as a
check upon the cleanliness and
strength Of the metal being used.
"a single defective part in steer
ing mechanism, we remember, might
at some future time cost a human
life, and every possibility of such A
part entering one of our cars must
be absolutely eliminated before that
part is assembled in the finished
chassis"