The Detroit times., 1911-04-15
KNOW ROMANCE
Of SPARK PLUG?
Its Making the Modern Development
of One of the Most Ancient
of the. Arts.

Almost every motorist knows what
spark plug is. II he doesn't be Is
not much OF a motorist. But compare
| lively few users OF automobiles could
tell you. right of the reel. SO to speak,
how spark plub is made. Although
the spark plug may seem Insignificant
TO the uninitated. it is a highly i'm
portant adjunct 10 the mechanism of
motor car and the processes EN-
ployed in it's manufacture are most
interesting
There are about SIS manufacturers
of spark plugs in this country today.
OF these only few, not 10 exceed Is
at the outside. make every part OF
their plugs from the raw material. II
is conservatively estimated that the
output OF spark plugs in the United
States for 1911 will amount to $500
900. at the rate of 81 per plug. This
is based on an estimate OF 4O0, 900 cars
now in use and on an estimated out
put of 10000 cars for 1911.
IL is difficult TO see where there
would be any romance about a spark
plug, but there is. The making or the
earthenware insulations is a modern
development of one OF the most an
Gent arts, the potter's art, which
marks back 10 prehistoric times.
The average spark plug is composed
OF shell OF steel, a packing nut or
bushing. a packing ring OF metal and
asbestos, porcelain insulator, brass
cap for the top of the porcelain in
suator. binding nut, a central cleo
trode and a ground electrode carried
on the she'll The shell is made from
a rod of cold rolled steel, which comes
from steel mills in round and hexagon-
al rods about IL feet long Four rods
are placed in an automatic machine.
which transforms them into large
number OF almost complete shells. A
| workman gathers the shells from a
hopper and carries them to another
machine, which cuts the external
| threads.
The next operation is the drilling Oh
! a small hole in the end OF the shell
-! to admit the small piece OF wire thai
! forms the ground electrode. The shell
| Ia then "smoothed up and sent TO the
Mating department, where IL Is thor
| oughly cleaned by immersion In sew
eral alkaline and acid baths before
being placed in the copper and nicke
plating baths. From the plating baths
! the shell. after being allowed to dry
! thoroughly, goes to the buffer, where
! II is polished.
! The packing nuts are made from the
same kind OF bars as are the sneHs
and the process is much the same ex
T, cept that they are completed on the
! enc machine. The nuts are then case
hardened by being packed In granu
lated charcoal and bone in cast lron
/ boxes and subjected TO an intense hea'
I for 55 minutes. When the boxes are
| removed from the oven they are dump
] ed into water, churned by blast o.
air The packing rings, brass caps
and binding nuts are all made by ma
chimes, the processes being Compare
/ lively simple.
IL is in the making OF the porcelain
parts of the spark plug that the great
est skill is required. To begin with
all the materials that enter into the
composition OF the ware are care
fully weighed and mixed with water
in fixed proportions AS the mixture
flows from the stirring watts series o.
magnets, so arranged that they extent
down into the stream, remove al
traces OF metal. The mixture passes
through a vibrating sieve into vat:
known as agitators. Next II is filtered
In a powerful press and is then trans
ferred to a plug mill where all the all
bubbles are driven out. The clay II
then stored in large bins for seyera
weeks. Next, when the clay is ready
for use, comes the kneeding process
and after that II goes TO the throw
ing room. where a Tiger forms 4
into cylindrical blanks, from which
the porcelains are turned In series o
delicate operations Baking, enamel
ling. assembling and testing operation
follow I'm quick succession and thu
plug Is ready for the market