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Full text of "Metallurgy Of Cast Iron"

CONTRACTION   VS.   STRENGTH   OF   CAST   IRON.        455                    !,
I1
often be found between the " temper " of sands in one              r|
shop.     All three bars were plaeed equidistant in the               j
mould and ^"ated  by means of two upright  lt sprues'1
which led down to a runner in the eope extending over
the three bars in the center, insuring the filling of the
three moulds at the same time with the same hand ladle
of iron.    The test bars formed in the chill and dampest
sand   showed   a   greater   contraction   than   the   ones
enclosed in the driest sand.     I have conducted quite a
11 umber of these tests and always found in. them the
same results, those cast in the chill showing the greater
contraction.    In several cases,   the extremes of one
flask   i^'ave   a   full   one-sixteenth    inch   difference   in
the contraction of the three bars.    In the extremes be-
!
tween the "temper*1 of the wetter and drier  sand, I
have found a difference of fully one thirty-second part                  <
of an inch to exist in  the  contraction of two one-half                 i inch bars poured from the same hand ladle at the same
moment, thereby proving" that a test  bar  as  small  as                 tj.
one-half inch square or round is  altogether  too  sensi-                 V
live to variation in the " temper" of moulding sand to                 l
be relied   upon  to  afford  any true  knowledge  of the                 (|i
natural contraction of an iron.                                                       <j,
To discover what effect, if any, degrees in dampness              (j or "temper" of sand  have  on  a round bar cast on
end,   I   took   a   pattern   one   and   one-eighth   inch   in              M,
diameter and made  a dry sand  mould, using" a piece              \
of six-inch ^*as pipe to mould  it  in, leaving both ends               Ij
open.     After this  little mould was dried in an oven,               }
it was set on end upon a planed plate and the distance              >;
equally divided between  two empty #as pipes.     Each               1 of these two latter  pipes  was then   rammed, up  with
" green sand " of a different  temper.     Each test bar               ,es ,u  ,i j and ;i,nds pe!' (on of iron, or a ratio of 7.7 iron to i coke, in onler to deliver the melted iron in the same condition as on an ordinary day. In other words, an additional fuel consumption <>!' a little over 3,h per cent, is needed under the above conditions......................    3,658 units