Evening capital news. (Boise, Idaho) 1901-1927, 1916-03-12
'nEAT TREATMENT
LATEST METHOD
Parts Subjected to Severe
Strain in the Chalmers
Plant.

One Of the most Important but least
understood processes connected with
the manufacturer OF the modern motor
gar. is the science OF heat treatment.
is an old axiom that mo motor car
is stronger than its weakest point"
The motor is the heart of the car and
by that motor the manufacturers
reputation must stand or fall
The heat treating department stands
out as the manufacturers chief insur-
ance against weak faulty parts in mo-
\ tor or chassis. In the Chalmers plant,
for instance. every part that is subject
ed to severe strain must run the
gauntlet Of thirty furnaces in the heat
treating department before it is ready
for use. Among the parts treated in
this department are steering arms,
crankshafts, connecting rods, cam
shafts and gears.
The camshaft, which must undergo a
s great share of the motor strain, is FIRST
: packed in a gas pipe about three inches
in diameter A carbonizing compoun
Is then poured into the pipe and
tamped lightly about the camshaft.
After the camshaft is packed snugly
away in its steel container the ends are
Eecurely plugged with fire clay and the
camshaft is ready for the carbonizins
furnace.
When the furnace has been stacked
high with camshafts the doors are
closed and The fire is turned on.
Terrific Heat Applied.
The heat generated in the carboniz-
ing furnaces ranges from 1850 to 1900
degrees Fahrenheit and is regulated
from central control presided over
by a tender whose sole business il Is
to keep tab on the temperature and
timing Each job which goes into the
fires Is registered on a separate card
which gives the tender a check on all
work in process. over each furnace
is d combination ht-indicator with
three colored lenses--blue. green and
red. When the blue light shows the
temperature is too low and more heat
y is applied When the red light shows
lit is danger signal indicating that
he heat is too intense. The ideal tenn
perature is indicated by the display Of
a green light When all three lights
are burning the job is done, and ready
TO come out of the furnace
Toushenina the Steel.
During the process Of earbonization
8 change takes place in the texture Of
the steel. In direct ratio to the length
OF time spent in the furnace the car
bon compound which surrounds the
camshaft penetrates the surface OF the
steel. The part which is carbonized is
called the case, and is much harder
than the core. or interior which has
not been reached by the carbon. To
carbonize the steel through to the core
would mean weakening OF the entire
camshaft, because the steel would be-
come brittle and lose its resiliency.
After the carbonizing process, the
shaft is ready for its first heat treat
ment to tougher the core. It Is again
placed In a furnace this time without
its gas pipe protector. Again the fire
is applied and the temperature raised
20 such a degree that the core is made
D tougher and more capable OF standing
severe strains. At the correct time,
the red hot shafts are lifted from the
nre and shot down an incline that
gives them a whirling motion as they
plunge into vat of water. This ro
tary motion assures that all parts will
reach the water at tile same time, SO
that cooling will be even.
Bath IN Boiling Oil.
third visit to the furnace follows
for the second heat treatment for case
hardening and closing the pores
Many makers omit the second treat
ment entirely, but Chalmers has in
cluded 1t as an extra factor of safety.
After the final heating the shaft is
again quenched in water.
The last step in the line Of heat
treating is a bath in boiling oil. This
bath Is administered to release any
!. strains or tension which the steel might
have undergone in previous ordeals by
fire. From the oil watts, the camshafts
are taken to the sandblast room. Here
a surface scale. which has accumulated
on the steel is removed by means Of
sand driven through hose under high
pressure.
Not until the green eamshaft has
passed through all these operations is
ii ready for the lathe work and finer
machining operations which render II
suitable for installation in the car