A Process for Casting in Aluminium Bronze Dies to be Used for the Purpose of Stamping Metals or other Substances for which Dies are used.
Year: 1889

page_text: Date of Application, 24th Sept., 1889-Accepted, 4th Jan., 1890
A Process for Casting in Aluminium Bronze Dies to be Used for the
Purpose of Stamping Metals or other Substances for which Dies
are used.
ROBERT HANNAN a partner of the Metallic Art Company of Glasgow being a
communication from John Joseph Charles Smith of Passaic New Jersey Fine Art
Founder, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement:
The object of the invention is to produce dies or matrices (used for stamping sheet,
metals or for prossing plastic materials in desired forms) by means of casting and
pressure such dies to he perfect copies of a relief pattern, requiring no subsequent
finishing up by the die-sinker; and to be of a hardness and strength equal to steel dies
or matrices.
In order to show the novelty and utility of my invention, I will make a few
remarks regarding the present known methods of producing dies or moulds.
Most of the dies used are cut in solid steel blocks by the labor of the die sinker
which is a slow and expensive operation to say nothing of the risk of losing the die
after it is cut by the required process of hardening. Dies or moulds used for
producing ornamental articles are the most expensive, and it requires an artist die
sinker of high rank to cut such dies right, and impart to the design a proper and
ornamental effect.. Being compelled to cut a desired design in reverse or intaglio
makes the task difficult, especially with large deep dies. For this reason ornamental
articles produced by stamping or pressing live as a rule a stiff appearance they lack
the soft and lofty swing of design produced in relief by an artist chaser or repoussé
worker. On account of the great cost of steel dies ent into a solid block and the last
mentioned difficulty, manufacturers of ornamented sheet metal goods, or pressed
articles often resort to casting the dies of iron, steel or hard metal compositions and
finishing them after by the labor of the die sinker. However, this mode of making
dies or moulds carries with it defects which, only too often, prove that such dies
are more expensive thin cut steel dies and are not so strong and perfect. The
following explanation will make this clear."
The thick heavy blocks of metal which are required for dies cannot be cast, by any
of the present-known methods, with such perfection and sharpness of fine outlines of
the design as dies require. The design in intaglio has to be worked over and finished
by the die sinker, which involves nearly as much work as cutting it into a solid
block. Then it often happens that while working over, and finishing a cast die the
die sinker finds underneath the apparently solid surface porous spots or bad places,
which render the die useless, and the work so far done is lost. Such a discovery may
not be made until the die is almost finished.
By means of my invention, I overcome all the stated existing difficulties and
produce dies of a hardness and strength equal to a forged steel die and obtain a
perfection and sharpness of design equal to the artist's hand-work.
By copying my dies from a pattern worked in relief by the chaser or repoussé
worker I reproduce in intaglio the same perfection in design as imparted to the
relief.
I will now describe with reference to the accompanying drawings my method of
producing dies and moulds by means of casting and pressure, using for that purpose
an apparatus of peculiar construction. In said drawings,
Fig. is a vertical sectional view of an apparatus for carrying out my

page_text: 84.5a perspective view thereot.
Fig.
Fi
is an under side view of the pattern and its frame.
is a vertical sectional view of the complete apparatus:
The apparatus is of cast iron and is composed of three principal parts cach having
a distinct function. A is a frame of such internal shape and size as I desire to make
the die or mould. In the drawing this frame is shown tapering toward the open
intaligo or face side so that dies cast therein will have the customary taper. The
frame A is provided with an interior lining B of refractory non-conducting material,
either asbestos or crucible clay. This lining is applied about one-sixteenth of an
incli iliick.
The frame A serves as the receptacle for the fluid metal and at the same time
answers as the mould to give shape to the die to be cast. The fining B serves to
prevent the too rapid cooling of the fluid metal, so as to allow time for the necessary
operation of casting and applying pressure on the fluid metal.
€
C is another frame provided with the flange e extending outward from the larger
edge of frame A. and another Hance c¹ extending inward therefrom. When the
frame is attached to frame A by means of screws, the flange extending inwardly
forma portion of a bottom to frame A.
1) is a block of such size as to pass loosely through the upper opening of frame C
and complete the bottoin of frame A. E is another block parallel to and of equal size
to block D. The blocks D and E are kept in parallel position to each other by means
of two dowel pins e. The block E serves as a plunger, or piston by means of which
pressure can be applied to the fluid metal, when such is poured in and enclosed in
frame A. The block D resting on block E as indicated, serves the purpose of taking
up the central shrinkage of the metal. The metal composition which I prefer to use
for dies is a composition of 10 per cent. aluminium and 90 per cent. copper. This
composition has a great shrinkage in cooling and when cast in thick blocks like dies
the outside cools more rapidly than the center.
To compensate for the slower cooling of the center and consequently at the place
for last contraction, I use the block D. As stated above said block being smaller on
its surface than the bottom side of the die, can be forced into the center of the fluid
metal during its different stages of cooling until it becomes solidified.
As the composition of which the die is made shrinks more than the block D which
is made of cast iron it therefore becomes as firmly held as if united to the die and so
remains a part.
The latter frame cis, internally, somewhat larger than the block or piston Exexcept
at the upper inward flange. The space between the piston E and the frame e serves
to receive a fire proof packing F, for the piston, which is made by ramming asbestos
fibre in the space around the piston. The packing F serves the purpose of pre-
venting the escape of fluid metal from the 'receptacle or mould A when a high
pressure is applied to it. G is a plain iron frame which is of the same size, on the
outside edge, as the frame A. on the upper edge. The inside of frame G is about
one half inch from the inside edge of frame A. The function of the frame G is to
strengthen and hold the relief pattern H from which an impression is to be taken,
thereby obtaining the intaglio of the pattern.
The relief pattern H is made of fine plastic clay and burnt or baked, as hard as
what is called by potters biscuit burning. This clay pattern H is so formed as to
have a flat base or back h. The lase or back is exactly of the same thickness as of
the frame G and a little smaller than the inside of the frame so that the pattern
forming one piece with its base can be placed inside of the frame, leaving about one
eighth of an inch space between the frame and the pattern base. This space is filled
carefully with plaster of paris; thereby cementing the pattern base firmly in the
frame. When the pattern is thus united with the frame G; a sirip of asbestos
sheathing is pasted around the edge of the face side to form a packing between
frame A. and frame G when the last named is placed face down on frame A as is
indicated by the drawing figure 4.

page_text: After cementing the burnt clay pattern in the frame G, and providing the
packing strips J on the face side, the pattern must be again well dricil to expell all
moisture before using it for the impression.
The frame G has two steady or dowel pins g on opposite corners.
These pins fit
loosely in corresponding holes in the top odge of frame A thus permitting the placing
of the frame G with its pattern quickly in the desired position on the frame A, thus
completing a mould for a die to be casi.
The four spiral spings K one at each corner of the apparatus serve the purpose of
giving a certain, but yielding resistance, to the combined frames A, C and G when
pressure is applied on the top. This resistance of the springs very desirable,
although under certain modifications of the apparatus it may be dispensed with.
As seen by the drawings the whole apparatus rests on the piston E which is from
one to two inches longer than the depth of packing frame C, which is only prevented
from slipping down over the piston E by the friction of tho packing F. It is however
necessary that the combined frames C and A with the pattern fraine G on top, should
not move down against the stationary piston until the frame A forming the metal
receptacle, is filled with fluid metal from the top and the pattern in frame G has been
placed on the frame as a cover, the final completion of the mould. The resistance of
the springs must be considerably inore than the combined weight of the frames and
metal, for this reason:The pattern in its frame G is only laid on the filled frame A.
and is prevented from moving laterally by the two steady pins. If the metal
receptacle A is filled and the pattern placed on top as a final cover, which must be
done quickly without loss of time, because fluid refractory metals congeal very rapidly
when once poured from the melting pot, it is self evident that no extra special time
can be lost by fastening the frame G firmly to the frame A, so as to prevent the
escape of the fluid metal when pressure is applied to it, which I accomplish in my
case by shifting the whole filled apparatus under a suitable screw-press and forcing the
combined frames downward against the piston E. The surplus resistance of the
springs requires a corresponding pressure which is exercised on the frame G, thereby
pressing it tightly on the frame A. preventing the escape of the fluid metal.
It may appear to a mechanical mind a rather peculiar mode of procedure to force
the metal receptacle downwards; it would seem more practical to have the pattern in
frame & fastened at the bottom of the receptacle and pour the fluid metal on the
pattern, then apply the pressure by forcing the piston downward in the metal;
however the great importance of making and manipulating the apparatus as I describe
it will be clearly seen that when this specification is completed.
The production of the clay pattern requires little description, because there are
several ways to make fine perfect copies from relief designs in plastic clay well
known to artisans skilled in the production of ornamente gods made of clays, I
prefer to take a fine perfect plaster of paris mould from the original relief pattern,
which may be modeled in wax, or be made of sheet metal, by the artist chaser or
repoussé worker. From such a plaster mould, when well dried I take fine perfect
impressions in plastic clay and harden them by burning in a furnace to the required
degree.
Before I proceed to describe the final operation in casting a die with the apparatus
described in this specification I shall have to make a few important explanations con-
cerning metal compositions used for casting dies and moulds, also describe brieff some
of the properties of the above mentioned aluminium and copper compositions which I
prefer for casting dies and moulds. I have heretofore in actual practice, cast many
dies and moulds of cast iron, phosphor bronze bell metal, also aluminium bronze and
even steel, but I made such castings by other methods and by means of other
apparatus for applying pressure to the fluid metal the results of which were not
Satisfactory and perfect.
The first three metals have not sufficient strength and hardness to assist the high
crushing pressure required for stamping metals, or pressing other tough materials into
the required shapes. Cast steel on account of the high temperature required to melt
it, does not cast very sharp and with an even perfect surface. The high heat of the

page_text: fluid steel bites into the pattern, even when made of the most refractory clays.
Aluminiun bronze of the stated mixture is a composition presenting many peculiar
features when cast in heavy blocks. Metals when poured in a mould from an injecting
apparatus, are naturally brought in a state of agitation. In most of the metals and
compositions this agitation produces no serious results, because the spattering parts of
some of the metal in entering the mould will again unite perfectly with the mass and
the casting shows no signs that such spattering or temporary division of the fluid
metal had taken place. In casting the said aluminium bronze the above mentioned
agitation, spattering and division of the metal, while entering the mould produces
serious defects in a casting. The scattering or divided portions will not. unite perfectly
again; the whole surface and even the interior portion of the casting, is full of defects,
presenting an appearance as if the metal had been full of impurities, but in reality it
proves to be under close and careful examination small portions of metal which may
have become separated from the mass, and no matter for how short a time such.
separation may have been, they become surrounded with a film of oxidation which
prevents perfect union with the mass. It seems to be the same natural cause which
is antagonistic to the soldering of aluminium is its pure state. Another serious
trouble exists in casting the said aluminium composition which is the great contraction
while cooling. It amounts to nearly double the shrinkage of other bronze com-
positions. Furthermore this composition does not cool uniformly or simultaneously
like most metals. If cast in large blocks, the outside congeals much more rapidly than
the center which causes a drawing away from the pattern or mould in the center of
the casting thereby producing another imperfection. Pressure applied to the metal
through a gate or runner, as it is done by any of the present known methods, will not
prevent it, because the gate or runner is always smaller than the mass and con
sequently congeals sooner than the center of the mass. In the ordinary way of
casting aluminium bronze, in very open, coarse sand moulds, this defect is greatly
remedied by a large supply of sprues in the center, but such course, open moulds will
not answer for castings on which the finest line must be well defined.
By the use of my herein described apparatus and by the fundamental principle of
operation, I fully overcome the above mentioned difficulties of casting aluminium
bronze into a perfect die, mould, &c. The apparatus is plainly shown by the
drawing.
The fundamental principle of operation on which success depends is this:-The
metal composition is poured into a strong vessel open on the top and which has the
same shape as the outside of the die or mould to be cast. Such vessel is provided with
a non heat conducting lining The metal after being poured in said vessel has an
opportunity to come to a perfect rest and unity. When at rest it is skimmed off
and all impurities and oxidation are removed. It then presents a clean surface.
Placing the clay pattern from which an impression is to be taken on top, face down
the mould is complete. By applying pressure on the back of the frame G and
pattern H, the frames A and Care forced against the piston E, exercising pressure
on the still fluid metal, which with a clean surface comes in contact with the pittern
and receives a perfect impression of the same.
The metal in receptacle A becomes congealed on the outside to a certain extent.
during the performance of the operations of coming to a rest, being skimmed, placing
the pattern on top, & applying pressure, but the piston E and the block D being
smaller than the external size of the die, will still force casily into the center and
exercise the desired pressure on the metal thereby filling the mould completely
and at the same time taking up and filling completely any shrinkage in the center
of the casting.
Having now fully described the apparatus in its details and functions and having
laid down and explained the principle on which I operate, I will now shortly describe
the final operation of casting and pressing a die.
The apparatus being completes as shown in figure 1 is placed on an iron plate
(see fig. 4) and adjusted on a screw-press which must be provided with a projecting
platform or base. Such a press must be of a capacity to exercise a pressure of about

page_text: 400 lbs. to the square inch on every inch of the surface of the die to be cast. This
done the interior lining of the frame A is again heated to expell all moisture. The
pattern H in its frame G is removed and also reheated by means of a blow pipe and.
laid in readiness to be replaced quickly on top of the frame A. In the meantime or
previously thereto the aluminium composition has been melted in a proper suitable
furnace and pot. Then I fill the frame or receptacle A with the melted metal making
however proper allowance for the room or space which will be occupied by the
projection of the pattern. That is to say: for the formation of a large deep die the
pattern as a corresponding projection which takes the required space in the frame A.
To fill the frame A completely in such a case would cause an overflow when the
pattern is put in place which would cause an objectionable flange on the die and this
would be an impediment to its removal from the frame.
When the frame A is filled as stated the metal will bubble & show some
agitation which will however subside in a few seconds. As soon as the fluid metal
rests quietly all the foam and impurities are quickly skimmed off by means of a
suitable tool N. see ligure 2. When the skimming is done a perfectly clear mirror-
like surface of the fluid metal is presented. Then the clay pattern (see Figure 3) in
the frame G is quickly placed on top, face down, dropping in its place guided by the
steady pins and thereby closing the moulds. The whole apparatus resting on the
plare is then placed under the screw-pres which is quickly brought into
depressing action to the extent required, according to the size of the die's surface
(see figure 4).
The action of the press will move the combined frames A and C against the
stationary piston E. The bloc D will force itself into the center of the die which
is the last spot to cool and prevent the central skrinkage and become itself a part
of the die. In the course of a few minutes during which time the pressure is kept up
the metal has cooled enough to be removed by taking the apparatus apart and
knocking the die out of the frame A. Some portions of the clay pattern will adhere
to the die but may be easily removed by a little hand work and proper tools. When
che clay is removed it will be found that the die or mould is a perfect intaglio copy of
the clay pattern, a copy as perfect and true as the electrotype process would produce
it as a copper shell.
The whole surface of the die is free from any imperfections or defects, and the
whole body of the die is as solid and free from blow-holes as if it had been
forged.
In conclusion I wish to state that I do not coufine my claims to the exact type of
apparatus herein described. By many modifications of the apparatus which will not
require special faculties of invention, the same apparatus may be adaptable to sundry
shaped castings of which it is required to have one side of a perfection requiring
special hard labor to bring it to such. For illustration, the frame G may enclose a
clay mould formed from a pattern which presents two or three ornamented sides, or of
a peculiar shape. By observing the same rules and principles as described, the same
good results are obtained. A mould of an object enclosed in frame C is just as
perfectly filled by pressing the metal upward. It remains the same whether the
frame Gholds a clay relief pattern or a clay mould or matrix. I produce fine results
in casting artificial teeth moulds by a slight modification of my apparatus. Such
teeth moulds present three sides which have to be reproduced just like the original
mould.

page_text: 2. In the process of casting a die closing a filled mould or metal receptacle
with that portion of the mould which contains the design from which a perfect cast or
impression is to be obtained.
3. A burnt clay pattern surrounded by and fastened in a metal frame in the
manner and for the purpose described.
4. In combination with a metal receptacle, a movable bottom serving as a part of
the mould, and acting as a piston.
5. In combination with a mould and piston the block D for the purpose
described.
6. In combination with a mould and piston the flanged frame C, serving as a
packing box for said piston.
7. The combination of the frames A and C piston E and bloc D, for the purpose
described.
8. The combination of frames A and C. with piston Ę and a clay pattern held in a
frame G thereby forming a complete mould for to which pressure can be applied in
the manner specified.
9. The process of casting a die or matrix of refractory metals or alloys.consisting of
pouring the molten metal or alloy into an open topped mold, allowing the metal or
alloy to settle, skimming off the impurities, placing a pattern face downward
on the clean molten metal or alloy and applying pressure substantially as set
forth.
10. A die or matrix cast of aluminium bronze substantially as set forth.
11. Aluminium bronze as a material for casting dies for stamping metals & other
substances for which dies are used..
Dated the 54th day of Santa 1890