Improvements in or relating to the Manufacture of Moulds and Castings.
Year: 1898

page_text: Date of Application, 25th Feb., 1898.-Accepted, 23rd Apr., 1898
Improvements in or relating to the Manufacture of Moulds and
Castings.
A communication from the FRANCO AMERICAN CASTING COMPANY, of Philadelphia,
United States of America.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered Patent Agent, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:
This invention relates to an improved moulding and casting process ensuring
the production of very thin and light metallic castings under the best conditions,
with the greatest facility and of perfect form and whereby an absolutely exact
reproduction of the outlines and ornamental designs that may be arranged on
said castings in obtained.
This process comprises,
1. The production of a mould comprising an absolutely perfect and sharp
impression of the outline or of the ornamental designs of the objects to be repro-
duced by casting, which mould must be capable of resisting without deformation
very high temperatures and very high pressure produced in the interior by the
molten metal which has to be forced into it according to this process by mechanical
pressure in order to obtain a practical and complete application of the process.
2. A mechanical and practical device by means of which molten metals which
are difficult to cast by ordinary processes can be forced into the moulds in order
to ensure that the latter are perfectly filled, thus producing absolutely sharp and
perfect castings.
The material now generally used for forming moulds into which metals are cast
is moulding sand or loam but this material will not take such a sharp impression
as is required, if the casting is to be a perfectly sharp reproduction of a given
ornamental pattern. By a perfect reproduction is meant a casting which shall be
as fine, sharp and perfect in outline and design as can be done by means of the
electro type process.
The moulds according to the present invention have another great advantage
over sand or loam moulds. The composition employed is first in a semi fluid or
plastic condition and when it is in that state can be applied or cast on the pattern
or model and hardens quickly and becomes set without alteration of size or shrink-
age so that it may be used to produce perfect moulds from elastic patterns or
models which can be formed of vulcanized rubber etc.
By the use of such elastic patterns or models moulds and castings from patterns
or models which present numerous deep-undercuts can be produced just as easily
and quickly as if the pattern or model was a plain model. It saves the great and
tedious labour of making the so-called false cores in a mould. Workers in mould-
ing and casting works will fully comprehend the great advantage of making
moulds for casting metals by this method and with the compound herewith
described

page_text: The materials which are used for making moulds is a composition of fine asbestos
pulp and plaster of Paris preferably one part of fine asbestos pulp and two parts
plaster of Paris. The addition of the fine asbestos pulp to the plaster renders the
same fire or heat proof to such an extent that a mould made of the compound
can be exposed to a heat, high enough to expel the sulphuretted hydrogen con-
tained in the plaster, without cracking or injury to the mould.
If a mould made simply of plaster were exposed to this required heat it would
crack and fall to pieces.
The new and novel features in these moulds is that the sulphuretted hydrogen
can be expelled and the mould remain in a perfect condition. The removal of
the sulphuretted hydrogen renders the mould fit for casting most of the usual
bronze and brass compositions in such moulds, whereby sharper castings than in
the best made sand moulds are obtained. For making perfect silver or gold
castings these moulds are far superior to any other kind. The practical operation
for forming moulds from a given object with this composition is as follows. The
asbestos pulp is first mixed in a separate vessel with sufficient water to form a
thick cream like substance which is easily accomplished by thoroughly stirring
it up. The mass will stay in that condition and is ready at any time to be used
in combination with the plaster.
66
The procedure of forming a mould is about the same as followed by artisans
skilled in the art of forming moulds from a given object, differing only in that if
the pure plaster of Paris is mixed with water in the manner employed for making
plaster casts, to the plaster, while in a creamy" state, one part in bulk of the
asbestos pulp is added to two parts of the plaster mass, and the whole stirred well
together, after which it is applied to the object to be moulded, in the same manner
as plaster of Paris.
The mixture after being applied will set and become hard in the same manner
as plaster of Paris so that the pattern or model can be removed. A mould into
which metal is to be cast by pouring must consist of two main parts in the shape
of flat slabs perfectly straight and even on the outside surfaces so that the two
halves can be firmly held together by means of suitable clamping devices.
When a mould consists of two or more parts one side or part of the object is
first formed, then the other side is formed on the first part made by just the same
procedure as is followed in forming sand or plaster of Paris moulds. When a
mould is completely formed then the openings or gates for the inlet of the metal
are cut out in the manner indicated in Fig. 2 & which will be described hereafter.
The drying or burning of the moulds is done in any suitable drying oven:-
The heat is first moderately applied and gradually raised to about 150° C. for
Bay, about
to 8 hours which expels most of the moisture after the heat is raised
to about 400° C. for say 4 or 5 hours more, so that the moulds become not only 4
perfectly dry but also the sulphuretted hydrogen contained in the plaster is com-
pletely expelled. When the moulds are thus dried and burnt they are allowed to
cool off enough to sufficiently enable them to be handled when they are ready to
be filled with fluid metal by means of the casting apparatus a description of which
is as follows;-reference being had to the annexed drawings of which
Fig. 1 represents a side view in elevation.
Fig. 2 represents a vertical section through the centre of the apparatus.
Fig. 3 being a front elevation and
Fig. 4 a plan or top view of the same.
The same letters of reference denote the same parts in the different figures.
The construction of the apparatus is as follows-
To a vertical plate B a horizontal plate or platform A is attached the end of
which rests on a leg A²
The lower portion of the vertical plate B ends in two
parts forming legs B³.
4
To both edges of the plate B plates C C are attached by means of strong 5
hinges D D so that the plates C C can be swung out like doors. The plates C C

page_text: are provided at their other free edges with strong hook or lugs E for the purpose
of receiving removable yoke or tee bars F each of which is provided with two long
screws G.
At each end of the yoke bars is a short hook or projection F³. The
vertical plate B in combination with the horizontal plate A the hinged plates C C
and a movable ribbed plate H forms a strong box or casing which can be made
larger or smaller by moving the plate H backwards or forwards.
The yokes F fitting loosely in the lugs E with their short hooks will lock into
the lugs E and hold the plates C firmly in position. The yokes F form also the
fulcrum point or support for the screws G which operate on the movable plate H.
The combination of the several described parts forms the receptacle or casing
for the moulds to be filled with metal under pressure.
If one or more moulds, made in the manner above described, are placed into their
casings, they can be quickly adjusted and held firmly together by turning the
screws G against the movable plate H which in turn presses the moulds together
and closes the joints of the moulds perfectly, so as to resist the pressure exercised
by the fluid metal when the moulds are filled with the same. On the front surface
of the vertical plate B is an attachment consisting of a preferably cylindrical
receptacle J and movable piston K both in vertical position.
The cylindrical receptacle J is formed of two parts it being vertically divided
in the centre. The part J is fastened to the plate B and is stationary. The other
part J is movable on a hinge joint L so that it may be swung away from the other
part J. The object of which will be described hereafter. The bottom of the
cylindrical vessel is attached to the movable part J2 and a tail like extension of
the bottom forms the hinge. A spout M attached to the movable part completes
this receptacle. The movable piston K fits loosely into the receptacle J. It is
movable in and kept in place by a guide arrangement N and is operated by means
of a pinion gear O acting on a rack P, formed on the piston K. The force is
applied by means of a crank lever Q. The reason of making the cylindrical
receptacle in two halves will appear hereafter as an essential feature.
The movable half of the cylindrical receptacle is held in position by means of
bolts R. The drawings Fig. 2 shows an aperture S which passes through the front
plate B at a point just level with the bottom of the receptacle. This aperture S
forms the passage way for the fluid metal from the metal receptacle to the
interior of the moulds enclosed in the casing.
The aforesaid receptacle J serves the purpose of receiving the fluid metal from
which it is forced into the moulds by means of mechanical pressure applied by the
piston K operated by the pinion gear O and crank lever Q.
In order to prevent the rapid chilling or solidification of the fluid metal when
poured into the metal receptacle J the same is provided with a non heat conducting
lining T on its interior.
This lining is formed preferably of asbestos sheet felting of about one millimetre
in thickness formed over a suitable shaper or former.
This lining cylinder is also provided with a bottom U made of the same
material. This lining cylinder is readily placed in the metal receptacle J when
the movable part J2 is swung out on its hinge. When the same put back and
fastened in its place the lining will adjust itself snugly to the walls of the
cylindrical receptacle. This lining serves three important functions, firstly the
lining T serves as a non-conductor of heat and keeps the metal fluid whilst in
the receptacle J until it is forced into the mould. Secondly the lining serves as a
packing to prevent leakage of the metal between the walls of the receptacle and
the side of the piston which if it took place would at once chill and prevent the
piston from being moved. Thirdly a function of the lining is to close the aper-
ture S, temporarily and prevent the fluid metal from entering the moulds before
pressure is applied.
The lining lays over or covers the apertures S like a diaphragm and is strong

page_text: enough to resist the pressure of the weight of the fluid metal but allows the metal
to break through into the passage S as soon as a higher pressure is exercised on
the fluid metal by means of the piston.
The manner of gateing the moulds is shown in Fig. 2. At the lower end of the
mould is a passage S¹ equal in size to the aperture S in plate B. This passage is
cut through the mould at a point where it will coincide with the aperture S when
the mould is placed vertically against plate B. In fact the passage S¹ forms a
continuation of the passage S. All moulds to be cast are provided with the same
passage so that if 2, 3 or more moulds are to be enclosed in the casing for being
filled with metal at one operation the passage S¹ in each mould will coincide with
the others is called the general gate or sprue from which each mould takes its
supply of metal. From this general gate S smaller main gates or passages are cut
which branch out into several still smaller ones which lead at several suitable
places to the mould in a similar manner to that employed in moulds formed of
moulding sand or loam.
To perform the operation of casting or filling the moulds remove the yoke F
and open the side plates C. Then place a mould vertically against plate B so
that the passage S¹ coincides with the passage S. Then place the second and third
moulds in the same. Then move the plate H against the moulds bring the side
plates Cup to the moulds and put the yoke bars F in the lugs E and press the plate H
firmly against the moulds by gradually and uniformly turning the screws G
against the plate H so that the moulds are firmly closed up against each other.
When this is done swing the receptacle J down place in it one of the cylindrical
shaped linings T which must be perfectly dry put the receptacle back in place and
fasten it to plate B by means of the screws R. The apparatus is then ready to
receive a charge of metal to be forced into the moulds. When the metal is
properly melted and at a casting heat it is poured into the receptacle J through
the spout M attached to the same. The receptacle is almost filled say to about
10ths of its capacity. Then bring down the piston K by means of the lever and
exercise a moderate pressure on the fluid metal. The pressure will cause the metal
to break through the lining over the passage S and allow it to pass to the moulds.
The pressure on the piston is followed up as it descends and as it follows the
escaping metal.
When the moulds are completely filled the operator feels a
resistance to the downward movement of the piston which indicates that the
moulds are filled. The pressure is maintained for a few minutes to keep the metal
in position until it is chilled in the moulds. Then the piston is raised the recep-
tacle loosened and swung down and the surplus metal that remained in the
receptacle broken off so that the main or general gate may be pushed back with
the filled moulds. The yokes F are then loosened and the side plates opened and
the moulds removed with the castings which are afterwards cut from the gates
and cleaned of any adhering moulding material.
Having fully explained the invention and mode of operation its novel and useful
points may be pointed out as follows,
Firstly by the use of the improved moulding compounds for sharper and more
perfect moulds can be produced than it can be done by the systems at present
in use.
Secondly, Moulds of undercut objects or models by the use of elastic models can
be provided with a great saving of labour and giving results that can not be
obtained by the present methods of moulding.
Thirdly, These moulds are suitable for casting most of the bronze and brass
compositions with a sharpness and perfection equal to an electro copper deposit.
Fourthly, For the production of castings of silver and gold these moulds are
superior to any other material or method of moulding.
Fifthly, By means of the casting apparatus and the improved moulds very light
and thin castings can be produced such as cannot be made in cement or by any other
moulding process.

page_text: Having now particularly described and ascertained the nature of this inven-
tion as communicated to me by my foreign correspondent and in what manner the
same is to be performed I declare that what I claim is:-
1. A mould for use in casting metals formed of a composition consisting of
asbestos pulp and plaster of Paris.
2. In apparatus for use in forcing fluid metals into moulds a receptacle as J for
fluid metals provided with a non heat conducting lining T formed of asbestos felt
substantially as and for the purpose described.
3. The combination and arrangement of a piston K with a fluid metal receptacle
substantially as described.
4. A hinged receptacle for fluid metal substantially as and for the purpose
described.
5. The combination and arrangement of parts constituting the complete
apparatus for use in forming cast metal articles substantially as described or
illustrated in the accompanying drawings.
Dated this 25th day of Fahmim 1808
BOULT & WADE,
Agents for the Applicant.