Improvements in or relating to Cores, Molds, and Mold-facings for the Manufacture of Steel and other Metallic Castings.
Year: 1893

page_text: Date of Application 28th Nov., 1893-Accepted, 30th Dec., 1893
COMPLETE SPECIFICATION.
Improvements in or relating to Cores, Molds, and Mold-facings for
the Manufacture of Steel and other Metallic Castings.
I, REGINALD HADDAN, of the Firm of Herbert Haddan & Co., of
18, Buckingham Street, Strand, W.C., London, Patent Agent, do hereby
declare the nature of this invention a communication to me from abroad by
Benjamin Jones, of Cleveland, Ohio, United States of America, Molder, and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:—
This invention relates to improvements in cores, molds and mold-facings for the
manufacture of steel and other metallic castings, and in the process of making
same, the object being to produce a core, mold or mold-facing capable of with-
standing the intense heat had in the manufacture of such castings, and that will
shrink approximately with the casting in cooling and will cleave readily from the
casting, and whereby a casting whose surface is perfectly smooth and free from
scoria, &c., may be obtained.
The improved core, mold, or mold-facing is made preferably as follows:-Take
5 parts of clean strong sand, such, for instance, as molding sand, to one part of a
suitable combustible substance, preferably flour, and thoroughly mix the same
while dry. The core, mold or mold-facing is built up of said compound, the latter
of course being dampened and tempered suitable for the purpose. The proportions
of sand and combustible substance or material used in making the compound may
be varied more or less according to circumstances but I would advise the use of too
much rather than too little sand.
The surfaces of the core, mold or mold-facing, after being built up as herein-
before described, is then coated with a wash composed as follows:-
Take 1 pound of sal ammoniac and dissolve the same in one gallon of hot,
preferably boiling hot water. Take five parts by weight of silica sand, ground
fine, and mix the same dry with one part by weight of plumbago. Then mix the
silica sand and plumbago mixture with the sal ammoniac water aforesaid to reduce
the mass to the consistency of a wash.
The mold or core is then coated with said wash and smoothed down and allowed
to dry slowly. The wash penetrates the core, mold or mold-facing for perhaps
one-half inch, more or less.
The core, mold or mold-facing having been built up and coated as hercinbefore
described, a binding and hardening substance or composition, preferably coal-tar, is
introduced so as to form one compound with the sand and flour or combustible
substance of the material of which the core, mold or mold-facing is composed.
This introduction of the coal-tar or binding and hardening substance is effected by
applying the same while in a hot liquid condition to the surface of the core, mold or
mold-facing until the mold, core or mold-facing has become thoroughly impregnated
with it and its gases, the core, mold or mold-facing being thoroughly dried and
heated preparatory to the introduction of the binding and hardening substance. It
may be said that the binding and hardening substance is burnt into the core, mold or
mold-facing. If all the gases in the tar or binding and hardening substance were
retained therein disastrous results would likely ensue in the operation of casting,
but by introducing it, as hereinbefore described, by burning the same into the core,
mold or mold-facing, enough of said gases is eliminated to avoid such results.
A core, mold or mold-facing composed as hereinbefore described presents a
smooth hard surface and will not only withstand the intense heat had in the
manufacture of steel-castings but will shrink with the casting in cooling owing to
the consumption or burning, after the operation of casting, of the flour or
D
27

page_text: combustible substance or material in the composition of the core, mold or mold-
facing, and will readily cleave from the casting.
I would here remark that I prefer to have the core, mold or mold-facing
saturated with the binding and hardening substance, so that the core, mold or mold-
facing shall be as solid as practicable.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A mold, mold-facing or core having its body composed of a compound of
sand and a suitable combustible substance coated with a wash of sal ammoniac,
silica and plumbago, and impregnated or saturated with a binding and hardening
substance or composition, substantially as set forth.
2. A mold, mold-facing or core, having its body composed of a compound
consisting of sand and flour coated with a wash of sal ammoniac, silica and
plumbago and impregnated or saturated with coal tar, substantially as set forth.
3. The process herein described of making molds, mold-facings and cores
consisting in building up the core, mold or mold-facing, of a compound composed of
sand and a suitable combustible substance or material, then coating the same with
a wash composed of sal ammoniac, silica and plumbago, and then impregnating or
saturating the same with a binding or hardening substance, substantially as set
forth.
4. The process herein described of making molds, mold-facings and cores,
consisting in building up the core, mold or mold-facing of a compound composed of
sand and flour in approximately the proportions specified, then coating the same
with a wash of sal aminoniac, silica and plumbago, and lastly impregnating or
saturating the same with hot liquid coal-tar, substantially as set forth.
Dated this 28th day of November 1893
R. HADDAN,
Of the Firm of Herbert Haddan & Co.,
18, Buckingham Street, Strand, London, W.C.