Mold.
The ma-
[
1459]
trix in which an object is cast.
A templet or shaper by which an object is tested for shape or marked to a shape.
1. (
Founding.) Molds for casting are of several kinds: —
Open molds, into which the metal is poured, the upper surface of the fluid metal assuming the horizontal position.
Such are ingots and some other objects.
Close molds of metal or plaster of
Paris, with ingates by which the molten metal enters.
Such are the molds for inkstands, cannon-balls, bullets, type, and various other articles made of lead, tin, zinc, and their alloys which fuse at a moderate heat.
Close molds of sand, in which articles of iron, brass, bronze, etc., are cast.
This is the ordinary foundry work, and includes machinery, stoves, ordnance, and the multitude of articles of domestic and agricultural hardware.
Loam-work casting, in which the mold is built up, instead of being rammed around a pattern, subsequently withdrawn.
This is used in casting cylinders, tanks, bells, or ordnance of very large size.
 |
|
Molds. |
For specific index see founding.
a is a mold of a car-wheel in sand, shown in section.
b is a section showing several small articles partially imbedded in the drag or lower portion of the mold.
c is a view of an article with undercut portions requiring a peculiar treatment by core pieces, which are taken away to remove the pattern, and laid back again before closing the mold.
d is a metallic mold for britannia and pewter ware.
e is a flask, the drag and cope being separated to show the parts.
See flask.
f shows a portion of the same, with the parts of the flask fastened by a clamp.
i j is an ancient mold for bronze knives, found in the lake of Brienne, and belonging to a period of several thousand years past.
It is a gray sandstone of great porosity, and has corresponding holes for the reception of wooden pegs to keep the parts of the mold in place.
It is about 12 inches long.
Roman coins were (sometimes) cast in molds, hollowed out in a kind of stone.
Molds were also used in making pottery, pastry, cheese, bricks, pise walls, shoemaker's lasts.
The invention of molds for the casting of wax figures is ascribed to
Lysistratus, about 328 B. C.
g h are molds for paper-making.
k is a plasterer's mold for shaping cornice.
The fusibility of metals and alloys is the basis of the founder's art, and furnishes one means by which they are given the varied forms which fit them for application in the arts.
The softer metals and alloys, such as lead, pewter, type-metal, britannia-metal, and even zinc, are usually cast into metallic molds which are used over and over again; but in a more restricted sense molding embraces the formation of molds in sand and loam only, and the filling of such with metals and alloys fusing above a red heat, as cast-iron, brass, gun-metal, bell-metal, etc. In all these cases the mold can be used but once; after pouring and cooling it is broken up to get out the casting, part of its sand only being used again.
The trade of the iron-molder is distinct from that of the brass-molder (who also deals with gun and bell metal), but the methods employed are so nearly identical, that a distinction in describing the several operations is not necessary.
a. Molds are made in
green-sand, dry-sand, and
loam. For the first two a
pattern is required; in the latter it is generally dispensed with.
Patterns are mostly made of wood, although brass and iron are also common, especially when large numbers are required.
A pattern always represents the appearance and dimensions of the casting as far as its external surface is concerned.
This is also frequently true of its internal surface, but not invariably so, dry-sand
cores made apart from the pattern being often introduced to form the cavities and internal spaces required.
(See core.) Patterns are sometimes made in two or more pieces fastened together by pins or dowels, the object being to facilitate their removal from the sand.
The term
green-sand molding is employed to express the fact that the sand is used pretty much in its
green or natural state, and is not subjected to any drying or baking process before casting; it is the method followed for the great mass of castings, both iron and brass.
The sand for this purpose is kept damp, sufficiently so to ball into a compact mass when squeezed in the hand, but it must not be wet, or approach that condition.
The brass-molder keeps his sand in a molding
[
1460]
trough or bin, over which he works; small castings forming the bulk of his work: but in an iron foundry the whole floor to a considerable depth is formed of
old-sand, and on this the surplus quantity for use is gathered together in large mounds.
In working from a pattern in green-sand the object in view is to produce in the finely packed sand a cavity identical in form with that of the pattern; the same being afterwards filled with molten metal and left to cool.
To accomplish this the workman is provided with a large assortment of
flasks, or
molding-boxes of the most various dimensions; they are designed to hold the sand used in making the molds.
Small flasks are simply rectangular frames resembling ordinary boxes, but without either top or bottom; each part being 3 to 6 inches high.
They are connected together generally in pairs (often three or more), by
steady-pins, which allow of their separation when full of sand, and their restoration to exactly the same relative position afterward.
Large flasks are provided with cross-bars at suitable distances to prevent the sand, which has been rammed into them, from falling out of its own weight, or rising from the upward pressure of the fluid metal.
In this country, flasks are frequently made of wood; only in the larger foundries is iron used to any extent; but in
Europe, and especially in
England, wooden boxes are rarely seen.
Even where iron is always used, wooden cross-bars are frequently employed with advantage, as they admit of being readily cut away to suit patterns of unusual form.
The lower side, or
drag, has generally only flat bars connecting its lower edges, so that it can be lifted, but not turned over after it is once full.
See flask.
The following description will serve to illustrate the principles which govern and guide the molder working in green-sand.
One flask being laid with its lugs uppermost is filled and rammed up with old-sand, and stricken off level with the joint of the flask: this is called a
false-part. If now the object to be molded has an elliptical form, as shown in section
b c,
Fig. 3188, the sand in the false-part is cut away roughly, so as to imbed one half of the pattern.
Some dry
parting-sand is next scattered over the surface.
This adheres to the damp sand, and prevents any union between such a surface and any other sand subsequently rammed upon it. After the parting-sand is blown off the exposed part of the pattern, the other side or
drag is put on, its steadypins entering the holes in the lugs of the false-part easily, but without shake.
Newly prepared sand,
facing-sand, is next sieved over the pattern in sufficient quantity to cover it completely; the box is filled with old-sand from the floor of the shop, and is carefully rammed up and stricken off. After provision is made for the escape of gases from the sand by prodding it all over with a sharp-pointed steel wire, known as a
vent-wire, the two flasks are held together and turned over on a bed prepared for the drag upon the floor, or on a flat board if the boxes are small, and the false-part, having done its work, is lifted off and emptied.
An exact
parting is now made with the trowel along the median line, if the casting be symmetrical, the damp facing-sand being added to or cut away sharply up to the pattern as occasion may require.
The
parting-line is, as a general rule, that line upon the pattern, as it lies in the sand, above and below which the sides of the pattern run inward from the perpendicular.
This is frequently an undulating line, but the parting surface always runs from it in all directions to the horizontal edge of the box. Parting-sand is now strewn over the whole, and the surplus blown off. The upper flask or
cope being replaced, a short cylindrical
runner-stick is thrust into the sand of the lower part at a convenient distance from the pattern; facingsand is sieved on, the box filled up with old-sand, rammed up, and stricken off as before.
The ventwire is then used as with the drag, the runner-stick withdrawn, and the opening left, through which the metal has ultimately to pass to the mold, is given a bell-mouthed shape.
Having arrived at this stage of the work, the molder, either alone if the box be small, or with the help of other workmen or the crane itself if it be large, lifts the cope steadily upward, leaving the pattern in the sand of the drag.
The cope is then usually turned over on wooden blocks for repairs and dressing.
The pattern is now to be
drawn from the sand.
This is done with the help of spikes or screwed rods, temporarily attached to it; with one or more of these it is lifted, being made to vibrate the while by rapid tapping with a piece of wood or iron, for the purpose of causing it to leave the sand readily.
The molder has now to repair with suitable tools any broken parts of the sand forming the mold, then to cut the
runners or channels from the opening left by the
gate-stick to the mold, along which the fluid metal finds its way; and lastly to dust finely powdered charcoal from a linen bag over the facing-sand surface, if the mold is for iron, and mill-dust or similar farinaceous substance, if for brass.
Charcoal, when this is used, is slicked down with the trowel and slicker as far as possible, so as to bring it into intimate contact with the damp sand.
The excess of dust in every case is blown off with the bellows.
When the top part is
closed, it occupies exactly the position it did before; the space then filled by the pattern being now vacant and in connection with the gate, the hot metal can therefore make its way so as to fill such space, the form of which it will be found to have taken when cold.
The foregoing may be regarded as typical of all solid work in green-sand, the imaginary case cited being almost the simplest possible.
When hollow work is required, especially if the cavities are long or tortuous, dry-sand or loam
cores (which see) are employed to form such openings.
These are made either by pressing damp sand of suitable composition into a sort of wooden mold, known as a
core-box (which see), from which it is removed and dried by artificial heat, or by attaining the same end by the use of plastic loam on a perforated barrel or
core-plate. When such a core is perfectly dry, having received a thin coat of a mixture of clay, water, and charcoal-dust, called
black-wash, it is placed in position in the mold.
This is determined, and the core is held in its place by making it longer than the hole in the casting, and letting the added parts rest in suitable cavities in the sand, made by projections on the pattern known as
prints. An ordinary water-pipe is a good illustration of this class of work.
The pattern for such a casting is solid, and has cylindrical projections of the inside diameter of the pipe at its ends.
The long core, through which runs a perforated barrel for the escape of gas, rests upon that part of the mold which is made by the prints, and completely fills those cavities; but it leaves a space all round which exactly represents the pipe, and which is finally filled by melted metal.
b. Dry-sand molding may be regarded as identical in all essential points with that in green-sand, save that the mold when finished is thoroughly and strongly dried by artificial heat.
By this treatment the sand especially prepared for the work is baked to a hard compact mass.
Dry-sand molding is chiefly used for heavy castings, where great solidity and
[
1461]
strength are required.
The drying is done in a heated room called the
stove.
c. Loam-molding is entirely distinct from the preceding methods of working.
Loam, as prepared for this purpose, is essentially to be regarded as a mixture of sand and clay, the latter in quantity sufficient to give a plastic character to the mixture when tempered with water to the consistence of mortar or plaster.
This material is much used for the construction of large molds and cores, and, as has been previously stated, it obviates the necessity for patterns — generally very costly ones — and core-boxes.
Loam cores are
struck up, usually upon a hollow perforated spindle covered with a layer of hay-rope.
The spindle — often consisting of common gas-pipe — is made to run in notched trestles upon which a board (
loam-board) rests parallel to the axis of the spindle.
The loam is heaped upon this board, while the spindle at a proper distance is made to revolve slowly before it by a simple winch-handle.
After it is thoroughly dried in the
drying-stove, it is turned to the exact size, black-washed, and dried again, when it is ready for use.
Loam-molding applied to large castings, such as cylinders, pans, or large water-pipes, is really conducted on principles quite analogous to the above.
As a typical instance, the molding of a large sugar or soap boiler's pan is here described.
Such a vessel is cast mouth downward.
A heavy, flat, cast-iron plate (
loam-plate)
b, in the form of a ring, is laid upon the low carriage or truck which runs in and out of the drying-stove.
The outside and inside diameters of this flat ring are respectively greater and less than that of the rim of the pan, and it is also provided with four heavy projections by which to move it and the mold upon it, by means of the crane, from the
stove-truck to the pit in the floor where the casting is made.
In the center of this ring rises a perpendicular spindle running in a long bearing provided for it in the carriage, and carrying a movable arm from its upper end. A hollow templet of wood of the exact sweep of the inside of the pan is now clamped to the cross-arm of the spindle, and the latter is lowered so as to bring one end of the templet down to the plate, and there it is fixed.
In revolving through a complete circle, the edge of the templet will now describe a figure representing the inside surface of the pan. A rough dome of common brick set in loam is now built upon the ring, keeping it two or three inches clear of the templet, and leaving an opening at top large enough for the spindle to turn in. Loam is then applied to the dome in two or three coats, and it is finally
struck-up, with the help of the revolving templet, to an exact form.
This structure is dried, and then black-washed, and is known in loam-molding as the
nowel. The templet used hitherto is now replaced by another which gives the form of the outside of the pan. With its help the
thickness is struck — up upon the nowel, in loam which contains a good deal of clay.
It will be seen that this application represents the thickness of metal required for the pan. When dry, it is likewise black-washed, and dried again; the last application in both cases being made to secure a parting.
A second cast-iron ring, also provided with heavy ears or lugs, is lowered down till it rests upon that part of the first loam-plate which extends beyond the
thickness, last applied.
A coating of wet loam is then put on with the hand to the surface of the
thickness, and a second done of brick is built right against it. When all is dry, the position of the second ring is marked, or secured with pins.
The crane is then made fast to it, and the
cope is lifted off. In all probability the thickness-loam in doing this will break to pieces; if it does not, it is gently knocked away, and both surfaces, that of the
nowel and
cope, are repaired and dressed, and finally blackwashed.
Before this is done the spindle is lifted out, and the opening in the nowel carefully closed; that in the cope usually plays the part of ingate.
When both parts of the mold are united, a space now remains corresponding to the
thicknenss removed, ready to receive metal.
By means of the crane, made fast to the lower ring, the whole is deposited in a pit, and old-sand rammed about it, so as to hold the cope down, and increase its power of resisting the lateral pressure of the metal, which is very great.
Adequate provision is also made for the easy escape to the surface of the gases generated by the hot metal, especially those forced inwards through the dried loam and brick-work of the nowel.
The formation of the ingate is also carefully attended to.
In smaller foundries, and sometimes in those with very perfect appointments, loam-molds are made so large as to render it necessary to dry them
in situ. In such cases slow-burning fires are made under them in the open shop, and the evaporation of the water is accomplished as best it may.
The
pouring of brass and iron castings is accomplished from crucibles or ladles respectively.
In large iron works several ladles, each containing from two to four hundred weight of metal, are often used simultaneously; for still larger masses, crane ladles holding six or eight tons are employed, and when such are insufficient the mold is filled by leader channels direct from the furnace.
Fig. 3189 shows several stages of the process of cylinder molding by the loam-work process.
A vertical axis
a is mounted upon a pedestal in the center of the plate
b, as shown in the figure, or it may be attached to the building or a beam of the roof.
A radial arm projects from this axis and carries a
templet c, which is maintained in rigidly perpendicular position by firm attachment to the radial arm, which rotates with or around the central axis, so that the edge of the templet describes a cylinder in its rotation.
 |
|
Cylinder-molding. |
d shows an interior cylinder built up of bricks and plastered over with soft loam, scraped into cylindrical form by the
templet c, which revolves on its axis.
When the surface is made smooth and fair, this part of the mold is dried; it is then brushed over with black-wash and again dried.
The charcoal-dust of the black-wash acts as a parting, to prevent the succeeding layers of the loam-mold from adhering to the first.
[
1462]
The cylinder thus made by templet
c c is the mold for the inner surface of the future cylinder.
It is the
core or
nowel.
The next figure represents another templet
e e, attached to the same axis, having an edge conformable in its outline to the
outside surface of the future steam-cylinder.
The distance of the edge of the templet
e e from the blacked surface of the
nowel is equal to the thickness required for the steam-cylinder.
Loam is placed on the nowel, and smoothed to shape by the revolving templet
e, which is then dismounted and the spindle removed.
The thickness of this loam is represented white in the figure.
This loam then receives a coat of black-wash, which prevents it from adhering to the coat to be placed outside of it.
f represents the mold in a farther stage.
A wall of bricks
g g is built around the previous construction, loam being carefully worked against the material which represents the thickness of the future cylinder.
The new work or
cope is now thoroughly dried, and afterward lifted off by means of a crane and a cross-beam with four chains, as shown at
j. This part of the process usually drags off the thickness of loam which represents the cylinder, and this commonly breaks out during the removal.
What remains is carefully picked out of the cope, as it has now served its purpose, and the interval existing between the
nowel and
cope, when the parts are restored to their proper relative positions, is to be filled with molten metal to form a cylinder.
When the cylinder requires
ports at the ends, or the short tube with flanges for attaching the steampipes, models of the tube are worked into the cope, and are afterwards withdrawn; the cores are made in core-boxes, and are partly supported by the outward extremity and partly upon
grains, or two little plates of
sheet-iron connected by a central wire, the whole being equal to the thickness of the metal at that point.
When steam passages are wanted, either along the side or around the cylinder, they are worked up in clay upon the thickness and duly covered in by the cope; their cores are supported, partly by their loose ends and partly by
grains, which become entirely surrounded by and fixed in the metal when it is poured.
The mold is now put together in a pit sunk in the floor of the foundry, and the top covered in with a loam-cake, perforated with holes for the entrance of the metal and the escape of the air. The
core is sustained by iron bars, and the
cope by iron rings, so as to withstand the pressure of the column of metal.
With some large cylinders, such as those of the Cornish pumping-engines, 80 to 100 inches bore and 12 to 14 in length, also the cylinders of the large blowingengines of blast-furnaces, the
nowel and
cope are made separately, as at
i. The
cope is built up and turned inside with a radius-bar; the
core is erected on a plate on the floor and turned on the outside to a gage; when dried, it is lowered into the cope by a crane.
A modification of the plan for loam-work casting of cylinders and similar large hollow articles, is found in making the cope divisible by a vertical joint, so as to separate laterally into two semi-cylindrical portions which rest upon semi-annular plates, so as to slip back while the thickness representing the metal is removed.
Large water-pipes are cast upon cores, which are made of a layer of loam upon a hay-band wound upon a perforated pipe, the pipe being supported on a bearing, and the loam turned off to a smooth surface, which is dried and black-washed.
The
thickness is laid on and black-washed, and this substitute for a pattern is molded in sand.
The core with its envelope is withdrawn, and the
thickness removed; the core is supported in the mold by the
prints at the ends and by
grains with long wires.
Pipes are also made from wooden patterns cut in halves through the axis.
The
drag and
cope respectively receive the impression of one half, and when the pattern is removed the mold is ready for the core and the making of the ingate.
The molds for crooked pipes and branches are frequently made in halves upon a flat iron plate.
An iron bar or templet of the curve required is laid down, and a semicircular piece of wood, called a
strickle, is used for working and smoothing the halfcore; next, a larger
strickle is used for laying on the thickness; the two halves are then fixed together by wires and molded from in the sand-flask; the thickness is now stripped off the core, which is fixed in the mold by its
prints, and, if needful, is supported also upon
grains.
The infinite variety of forms which the molder is daily called upon to reproduce, as well as the constantly varying conditions and materials with which he has to deal, renders his trade an arduous one, requiring much judgment, experience, and forethought.
For this reason, also, it is not possible to explain or even enumerate in the space at my disposal the endless modifications of the above typical cases which are constantly occurring.
As the best substitute for such exhaustive treatment, however, a list of materials and technicalities used in molding is appended, with explanations designed to elucidate this most important, interesting, and many-sided art.
d. (
Plaster-casting.)
Waste-molds are those which admit of but a single cast, from which they are subsequently removed by breaking.
Safe-molds are those made in a number of pieces, which are so arranged as to be withdrawn separately from the casting and admit of being put together again for a repetition of the process.
We are indebted for the invention to the Italians and French of the fifteenth, sixteenth, and seventeenth centuries.
With some elaborate subjects the number of pieces required has exceeded 700.
See also statuary casting.
e. Soft and perishable objects may be so molded as to produce a single casting by one of the several following methods, which are adapted to procuring castings of small animals, insects, flowers, feathers, ferns, sea-weed, wax-models, etc.
1. Support the object in the center of a small box by means of needles, one or two of which should be sufficiently large to form
ingates. Some fine rivermud is dropped into the box, and shaken around so as to adhere to the object.
When partially dry, a coarser grade of silt is thrown in, and successively coarse qualities until the box is filled.
The needles and ingate wires are now withdrawn, the mold burnt to reduce the object to ashes, which are shaken and blown out, when the mold is ready for pouring the metal.
2. Another method is to take the object itself or a wax model, such as that of a flower, and suspend it in a box while plaster of
Paris is carefully poured around it. The application of heat causes the object to burn or the plaster to absorb the wax, or, if the latter be in excess, it can be poured out. The strings by which the object was suspended are withdrawn, and the mold is ready for casting.
The castings may be covered with
gold or
silver by the electrotype process.
This plan was adopted in casting the feather of the equestrian statue of George III.
at Pall Mall,
London, and specimens of ears of wheat, flashy flowers,
[
1463]
such as coxcombs, and other beautiful objects, have been exhibited.
Branson, of
Sheffield, England, has pursued a somewhat analogous method in obtaining castings from ferns, algae, etc. A slab of gutta-percha is softened by boiling water, laid on a smooth metallic plate, dusted over with fine bronze-powder, and the frond impressed thereon by a flat upper plate, imbedding the frond in the gum. When cooled, the leaf is withdrawn, and the mold is used to obtain a casting or an electrotype, from which impressions in ink are obtained by the copperplate process.
Auer's plan of
nature-printing is to impress the frond into soft, polished sheet-lead, by passing between polished rollers.
The impression is used for printing, or a copy in a harder material is obtained by the electrotype process.
Wallis's
autographs were obtained by making drawings in a material which is salient upon the paper, so as to make an impression in the soft plate when the two are passed between the rollers.
The plate is used as in
Branson's and
Auer's processes.
molders' terms.
(Referred to at greater length under their alphabetical heads.)
Air or
foul air. The gases generated in casting, and driven through the sand.
Air-drain. A passage to conduct gases from molds deeply bedded in the floor of the molding-shop.
Air-gate. An opening at which displaced air escapes during pouring, and in which metal afterward rises.
Barm. Yeast used in the preparation of core-sand to render it adhesive.
Bellows. Used to blow loose sand or dirt out of the molds, or parting-sand from the pattern.
Blackening. Charcoal-dust applied to a mold to give smoothness to a casting.
Black-lead. Sometimes used for blacking molds or for mixing with sand.
Black-wash. A solution of clay and powdered charcoal applied to the surface of sand-molds, to give a clean skin to the casting; also used as a parting.
See sand.
Blow. The forcing of displaced air through the molten metal from insufficient vent.
Blown. The condition of a casting containing cavities caused by inclosed air.
Bot. A pear-shaped piece of stiff clay used to stop the flow of metal from the tap-hole of the furnace.
Bot-stick. The rod provided with a long wooden handle at one end, and a small round disk at the other, to receive the clay, used for
botting-off when the ladle is sufficiently full.
Box. A very common term signifying
flask; a contraction of
molding-box. See
Flask, below.
Brick. Used largely in loam-molding.
Burned in. Union produced by flowing hot metal in quantity over cold.
Burned sand. Sand, the tenacity of whose clayey portion has been destroyed by the heat of the metal.
See sand.
Case. A
cope.
Cast-gate. The
ingate at which the metal is poured in.
Chaplet. A wrought-iron stud to hold a core in position in a mold.
A
grain.
Charcoal. Used in dust, as dry
blackening, or in suspension with clay, as
black-wash (which see).
Chill. A piece of iron in a mold to suddenly cool the metal flowing against it and render it hard.
Clay. Used according to quality, — fire-clay for walls and boshes of furnaces, commoner for bricks and for loam.
Clay-wash.
Clay in solution for smearing the insides of molds and gaggers, to make the sand stick; for cementing the portions of cores; for strengthening loam and adding to charcoal to make
black-wash.
Cleaner. A tool of thin steel or brass, from 6 to 18 inches in length.
One extremity has a bent spatula blade; the other a short blade bent on the flat to a right angle.
Used for smoothing the molded surfaces and removing loose sand.
Coal-dust. Powdered coal added in certain quantities to green-sand, according to the quality of the latter.
Coke-dust. The same in effect as coal-dust.
Cope. The flask which is uppermost at the time of casting.
The
upper box or
top-part. The outside portion of the mold in
loam-work. Also called the
case.
Core. A mass of sand, molded and baked, and placed in a mold to form a cavity in a casting.
Core-bar. An iron bar to stiffen a core.
Core-barrel. A perforated iron tube to form a passageway for the gases passing off through the interior of a core.
Core-box. A mold in which a core is formed.
Core-pipe. A core-barrel.
Core-print. A portion of a core which rests in seats in the mold and supports the core in place
Core-sand. Coarse new sand with powdered loam.
Cotter. A key which locks the steady-pin of a flask.
Cow-hair. Used as a bond to increase the tenacity of loam.
Crane. The hoisting apparatus of a foundry to move heavy flasks, castings, etc. See crane; foundry-crane.
Deliver. A pattern is said to
deliver well when it leaves the sand without breaking down the mold.
Drag. The lower box or bottom part of the flask.
Draw. The taper of a pattern which enables it to leave the sand without impairing the mold.
To lift the pattern from the sand.
Drawback. A
false-core.
Drop. The fall of sand from the top-part into the mold.
Dry-sand. That description of molding done with loam and sand in due proportion, the mold being oven-dried before casting.
See sand.
Drying-stove. A heated room for drying dry-sand molds or cores.
Face-dust. Powdered charcoal for iron castings, mill-dust or pease-meal for brass.
It is dusted from a bag over the mold to improve the surface of the casting.
Powdered soapstone, rottenstone, graphite, or chalk is sometimes used.
Facing-sand. New-sand used in immediate contact with the pattern, being sifted thereon and then backed up with old-sand and rammed.
False-core. A mass of molded green-sand placed against the side of a pattern which is under-cut.
Before drawing the pattern, the false-cores are removed, and are restored before closing the flask.
Also called a drawback.
See
c,
Fig. 3188.
False-part. A flask temporarily filled with sand in which the pattern is sunk to a parting-line before ramming up the other side of the box which is to form the
drag. After turning over, the false-part is broken up and the parting properly made.
Feeding-rod. An iron rod for keeping open the
head or
riser at which hot metal is added from time to time as the casting contracts in cooling.
Fettle. To clean castings, remove
gits, fins, and
cores.
Fin. A thin sheet of metal extending along the
parting-line of a casting where the metal has insinuated itself between the parts of the mold.
Flask. The box or frame which contains the rammed sand forming the mold.
The upper part is the
cope, the lower the
drag.
Flow gate. An opening from the mold to the surface; in it the metal rises as it is poured into the cast-gate and fills the mold.
Gagger. A double book hung to the cross-bars of the toppart of a flask, and entering the sand which fills the deep part of a pattern, to enable the sand to be lifted out.
Gate. The opening through a mold into which metal is poured.
An
ingate. Also called
git.
Gland. A bent rod of iron forming a double hook to lock the parts of a flask together.
Grain. A piece of wrought-iron to hold a core in position.
A
chaplet.
Green-sand. The damp sand of the foundry prepared for molding.
See sand.
Hay-rope. A twisted hay-band wound about a core-barrel in making large cores.
Head. A
flow-gate or
riser over the largest part of a heavy casting, in which the hot metal rises, and into which metal is poured from time to time as the metal contracts.
Horse-dung. Introduced into loam, as hair into plaster, to form a bond in dry-sand molds.
Ingate. The opening through a mold at which metal is poured in. A
gate, git, runner.
Ladle. An iron vessel, coated with loam, and used to convey molten metal from the furnace and pour it into the mold.
One form is a
shanks.
Lantern. A perforated core-barrel, short, and of relatively large diameter.
Lift. The separation of the cope from the drag.
Loam. A mixture of sand and clay used in molding.
See sand.
Loam-board. A board resting on trestles, and holding the loam used in making cores.
Loam-plate. A flat cast-iron ring on which the
nowel and
cope rest in
loam-work. See
b,
Fig. 3189.
Loosening-bar. A rod extending upward from the pattern through the sand, and which is struck from opposite sides to loosen the pattern in the mold before lifting the top-part.
Metal. The founder's term for cast-iron.
New-sand. Facing-sand next to the pattern.
Odd-side. A permanent
false-part.
Old-sand. The sand of the foundry floor, killed by use, and not fit for
facing.
Open-sand molding. A mode in which molds are made in the floor of the foundry without any cope, and usually filled direct from the furnace.
Part. One portion of a
flask.
Parting. The line of separation between the sand rammed in the respective boxes or parts of the flask.
Parting-line. The line upon a pattern below which it is im-
[
1464]
bedded in the
drag, and above which it is in the
cope or toppart.
Parting-sand. Sand free from clay, which is scattered over a green-sand surface where a parting is to be made.
Pattern. The counterpart of a casting in wood or metal from which the mold in the sand is made.
Pease-meal. Dusted on as
facing for molds in brass casting.
Picker. A steel rod with a sharp point, used in picking out small patterns from the sand.
Pickle. Dilute sulphuric acid used in cleaning castings.
Piercer. A vent-wire.
Pot. A crucible, generally of graphite.
Print. A projection on a pattern which leaves a space in the sand for supporting a core in position.
Rammer. An implement for compacting the loam around the pattern in the flask.
Red brick-dust. Sometimes used as a parting-sand.
Riddle. A sieve to mix sand on the floor of the foundry.
Riser. An opening through a mold into which the metal rises as the mold fills, and through which more metal is poured in as the mass contracts.
Run. Said of a mold if the metal insinuates itself along the parting or otherwise leaks out.
Runner. A channel leading from the gate to the space left by the removal of the pattern from the mold.
Runner-stick. A pattern for forming the gate of a mold.
Run-through. When metal is poured in at one gate and runs out at another.
A process sometimes adopted in casting a piece solid to another piece already in the mold.
Sand. Crystalline particles of silica mixed with clay which confers tenacity.
Used as a material for ramming around patterns in molding.
See sand.
Sand-burned. Sand partially fused by the heat of the metal and adhering to the casting.
Scoring. The bursting of a casting due to strain in contraction.
Scrap-iron. The spattered masses of iron, wasters, and pieces of iron which have been previously cast.
Shanks. The ladle in which metal is carried from the furnace to the mold.
Shovel. The implement for heaping sand into the flask.
Shrinkage. The allowance of one eighth inch to the foot, which patterns are made larger than the casting required, to allow for shrinkage of the metal.
Shuttle. A spade-shaped implement by which the molder stop; the flow into the mold in casting direct from the furnace
Sieve. A wire-cloth sifter for distributing the sand over the pattern.
Skimmer. A bar to keep back slag and dross when pouring from the ladle.
Slag. A basic silicate of iron floating on the metal in the furnace or ladle, and which it is the business of the skimmer to push back in pouring.
Slicker. A small, polished tool for smoothing surfaces of sand in the mold.
Sow. A large channel in the floor of a foundry to hold metal, when heavy castings are to be made without the use of the ladle.
Staple. A piece of iron driven into the sand and projecting therefrom to hold a core.
Steady-pin.One of the dowel-pins which form a part of the locking device securing together the parts of a flask.
Stove. The drying-chamber for molds and cores.
Strickle. A straight-edge used to remove superfluous sand from a flask after ramming up.
Strike. The same as strickle.
Strong sand. Tenacious from abundance of clay.
Sullage. The scum, slag, dross floating on metal.
Sullage-piece. An additional length on the upper end of a casting to insure compactness of the lower part.
The sullagepiece is afterward removed.
Swab. A soft brush of frayed rope, used in wetting the parting-edge before drawing the pattern.
Swab-pot. An iron vessel to hold water for the swab.
Tap-hole. The opening from which iron flows from the cupola.
Tapping-bar. One for opening the tap-hole by removing the
bot of clay.
Thickness. The portion of loam, in loam-molding, which represents the object to be cast.
Trestles. Frames on which the perforated core-barrels rest in pipe-molding
Trowel. A flat-bladed implement used in slicking and parting sand in the mold.
Under-cut. The parts of a pattern in which the sand would be broken by drawing the pattern perpendicularly.
The difficulty is avoided by cores, drawbacks, or an additional part to the flask.
Vent. A channel by which air escapes from the mold.
Vent-wire. A sharp-pointed steel wire for piercing sand in the mold to allow escape of air.
Waster. A spoiled casting; goes to the scrap-heap.
Watering-can. One with a rose to damp the molding-sand.
Weighting. Blocks put on a flask to keep the cope down under the upward pressure of the body of iron poured into the mold.
2. (
Building.) A frame to give shape to a structure, as in the building of houses in concrete, beton, clay, cement, and what not. In the example, the molds are made in inner and outer sections, which sustain the joists and door and window frames, and between which the concrete walls are formed.
The molds are perforated for admission of air, which supplies carbonic-acid gas. Composition used: sand, 19; hydraulic lime, 1/2; quicklime, 2.
 |
|
Sectional mold for Pise and concrete walls. |
3. (
Paper-making.) Hand-made paper is made by a
mold g and
deckle h,
Fig. 3188. The mold is an open, square frame with a wire-cloth bottom, and a little larger all round than the required sheet of paper.
The
deckle is an open frame, whose inner margin determines the size of the sheet of paper.
The
deckle being laid on the mold, the two are dipped into the pulp, of which a quantity is raised, the superabundance flowing over the edge.
The mold being shaken, the water drains away through the wire-cloth, and the fibers become felted together and settle upon the wire.
The
dipper then removes the
deckle and passes the mold to the
coucher, who lets it drain a few seconds, and then
couches the sheet of pulp upon a felt cloth.
A stack of alternate sheets and felts to the number of 6 quires of paper, = 144 sheets, forms a
post, which is placed in a screwpress and consolidated.
 |
|
Mold-blacking machine. |
4. (
Plastering.) A thin board cut to a pattern and used in forming cornices, etc. (
k,
Fig. 3188.)
5. (
Shipbuilding.)
a. A full-sized pattern of the same figure and dimensions with the molding side of the piece which it represents.
The mold may be of skeleton form, and may serve for several frames.
It is usually a thin plank cut to the form of a ship-timber, and serving as a templet for scribing the timbers for the workmen who saw, hew, and adze them into shape.
[
1465]
6. (
Gold-beating.) The package of gold-beater's skin in which gold-leaf is placed for the third beating.
It is first enveloped in vellum, 150 leaves with interposed ribbons of gold, one inch square, forming a
kutch. The pieces, spreading to the size of the vellum, are cut into four pieces and interleaved with gold-beater's skin; 600 pieces and their skin form a
shoder, for the second beating.
Being again divided into four pieces, they are again interleaved with gold-beater's skin, making 2,400.
These are divided into three packages of 800 each, called
molds, and receive the third beating.
