Tea Leaf.ca - Learn how to read tea leaves. Visit Tea Leaf.caInformational Site Network Informational
Privacy
   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Manufacturing

Extending The Time Of Action Of Forces
45. This is one of the most common and most useful of the em...

On Contriving Machinery
318. The power of inventing mechanical contrivances, and of ...

Distinction Between Making And Manufacturing
163. The economical principles which regulate the application...

Registering Operations
65. One great advantage which we may derive from machinery is...

Saving Time In Natural Operations
47. The process of tanning will furnish us with a striking i...

Of Copying By Punching
133. This mode of copying consists in driving a steel punch ...

On The Future Prospects Of Manufactures As Connected With Science
453. In reviewing the various processes offered as illustrat...

On The Method Of Observing Manufacturies
160. Having now reviewed the mechanical principles which reg...

Of Price As Measured By Money
201. The money price at which an article sells furnishes us ...

On The Influence Of Verification On Price
181. The money price of an article at any given period is us...

On The Causes And Consequences Of Large Factories
263. On examining the analysis which has been given in chapt...

Of Copying
82. The two last-mentioned sources of excellence in the work ...

On The Position Of Large Factories
277. It is found in every country, that the situation of lar...

Of The Identity Of The Work When It Is Of The Same Kind And Its Accuracy When Of Different Kinds
79. Nothing is more remarkable, and yet less unexpected, than...

On The Effect Of Machinery In Reducing The Demand For Labour
404. One of the objections most frequently urged against mac...

On The Cost Of Each Separate Process In A Manufacture
253. The great competition introduced by machinery, and the ...

On Combinations Amongst Masters Or Workmen Against Each Other
353. There exist amongst the workmen of almost all classes, ...

Enquiries Previous To Commencing Any Manufactory
298. There are many enquiries which ought always to be made ...

Of Raw Materials
210. Although the cost of any article may be reduced in its ...

Economy Of The Materials Employed
77. The precision with which all operations by machinery are ...



Of Copying By Moulding








112. This method of producing multitudes of individuals
having an exact resemblance to each other in external shape, is
adopted very widely in the arts. The substances employed are,
either naturally or by artificial preparation, in a soft or
plastic state; they are then compressed by mechanical force,
sometimes assisted by heat, into a mould of the required form.

113. Of bricks and tiles. An oblong box of wood fitting upon
a bottom fixed to the brickmaker's bench, is the mould from which
every brick is formed. A portion of the plastic mixture of which
the bricks consist is made ready by less skilful hands: the
workman first sprinkles a little sand into the mould, and then
throws the clay into it with some force; at the same time rapidly
working it with his fingers, so as to make it completely close up
to the corners. He next scrapes off, with a wetted stick, the
superfluous clay, and shakes the new-formed brick dexterously out
of its mould upon a piece of board, on which it is removed by
another workman to the place appointed for drying it. A very
skilful moulder has occasionally, in a long summer's day,
delivered from ten to eleven thousand bricks; but a fair average
day's work is from five to six thousand. Tiles of various kinds
and forms are made of finer materials, but by the same system of
moulding. Among the ruins of the city of Gour, the ancient
capital of Bengal, bricks are found having projecting ornaments
in high relief: these appear to have been formed in a mould, and
subsequently glazed with a coloured glaze. In Germany, also,
brickwork has been executed with various ornaments. The cornice
of the church of St Stephano, at Berlin, is made of large blocks
of brick moulded into the form required by the architect. At the
establishment of Messrs Cubitt, in Gray's Inn Lane, vases,
cornices, and highly ornamented capitals of columns are thus
formed which rival stone itself in elasticity, hardness, and
durability.

114. Of embossed china. Many of the forms given to those
beautiful specimens of earthenware which constitute the equipage
of our breakfast and our dinner-tables, cannot be executed in the
lathe of the potter. The embossed ornaments on the edges of the
plates, their polygonal shape, the fluted surface of many of the
vases, would all be difficult and costly of execution by the
hand; but they become easy and comparatively cheap, when made by
pressing the soft material out of which they are formed into a
hard mould. The care and skill bestowed on the preparation of
that mould are repaid by the multitude it produces. In many of
the works of the china manufactory, one part only of the article
is moulded; the upper surface of the plate, for example, whilst
the under side is figured by the lathe. In some instances, the
handle, or only a few ornaments, are moulded, and the body of the
work is turned.

115. Glass seals. The process of engraving upon gems requires
considerable time and skill. The seals thus produced can
therefore never become common. Imitations, however, have been
made of various degrees of resemblance. The colour which is given
to glass is, perhaps, the most successful part of the imitation.
A small cylindrical rod of coloured glass is heated in the flame
of a blowpipe, until the extremity becomes soft. The operator
then pinches it between the ends of a pair of nippers, which are
formed of brass, and on one side of which the device intended for
the seal has been carved in relief. When the mould has been well
finished and care is taken in heating the glass properly, the
seals thus produced are not bad imitations; and by this system of
copying they are so multiplied, that the more ordinary kinds are
sold at Birmingham for three pence a dozen.

116. Square glass bottles. The round forms which are usually
given to vessels of glass are readily produced by the expansion
of the air with which they are blown. It is, however, necessary
in many cases to make bottles of a square form, and each capable
of holding exactly the same quantity of fluid. It is also
frequently desirable to have imprinted on them the name of the
maker of the medicine or other liquid they are destined to
contain. A mould of iron, or of copper, is provided of the
intended size, on the inside of which are engraved the names
required. This mould, which is used in a hot state, opens into
two parts, to allow the insertion of the round, unfinished
bottle, which is placed in it in a very soft state before it is
removed from the end of the iron tube with which it was blown.
The mould is now closed, and the glass is forced against its
sides, by blowing strongly into the bottle.

117. Wooden snuff boxes. Snuff boxes ornamented with devices,
in imitation of carved work or of rose engine turning, are sold
at a price which proves that they are only imitations. The wood,
or horn, out of which they are formed, is softened by long
boiling in water, and whilst in this state it is forced into
moulds of iron, or steel, on which are cut the requisite
patterns, where it remains exposed to great pressure until it is
dry.

118. Horn knife handles and umbrella handles. The property
which horn possesses of becoming soft by the action of water and
of heat, fits it for many useful purposes. It is pressed into
moulds, and becomes embossed with figures in relief, adapted to
the objects to which it is to be applied. If curved, it may be
straightened; or if straight, it may be bent into any forms which
ornament or utility may require; and by the use of the mould
these forms may be multiplied in endless variety. The commoner
sorts of knives, the crooked handles for umbrellas, and a
multitude of other articles to which horn is applied, attest the
cheapness which the art of copying gives to the things formed of
this material.

119. Moulding tortoise-shell. The same principle is applied
to things formed out of the shell of the turtle, or the land
tortoise. From the greatly superior price of the raw material,
this principle of copying is, however, more rarely employed upon
it; and the few carvings which are demanded, are usually
performed by hand.

120. Tobacco-pipe making. This simple art is almost entirely
one of copying. The moulds are formed of iron, in two parts, each
embracing one half of the stem; the line of junction of these
parts may generally be observed running lengthwise from one end
of the pipe to the other. The hole passing to the bowl is formed
by thrusting a long wire through the clay before it is enclosed
in the mould. Some of the moulds have figures, or names, sunk in
the inside, which give a corresponding figure in relief upon the
finished pipe.

121. Embossing upon calico. Calicoes of one colour, but
embossed all over with raised patterns, though not much worn in
this country, are in great demand in several foreign markets.
This appearance is produced by passing them between rollers, on
one of which is figured in intaglio the pattern to be transferred
to the calico. The substance of the cloth is pressed very
forcibly into the cavities thus formed, and retains its pattern
after considerable use. The watered appearance in the cover of
the volume in the reader's hands is produced in a similar manner.
A cylinder of gun-metal, on which the design of the watering is
previously cut, is pressed by screws against another cylinder,
formed out of pieces of brown paper which have been strongly
compressed together and accurately turned. The two cylinders are
made to revolve rapidly, the paper one being slightly damped,
and, after a few minutes, it takes an impression from the upper
or metal one. The glazed calico is now passed between the
rollers, its glossy surface being in contact with the metal
cylinder, which is kept hot by a heated iron enclosed within it.
Calicoes are sometimes watered by placing two pieces on each
other in such a position that the longitudinal threads of the one
are at right angles to those of the other, and compressing them
in this state between flat rollers. The threads of the one piece
produce indentations in those of the other, but they are not so
deep as when produced by the former method.

122. Embossing upon leather. This art of copying from
patterns previously engraved on steel rollers is in most respects
similar to the preceding. The leather is forced into the
cavities, and the parts which are not opposite to any cavity are
powerfully condensed between the rollers.

123. Swaging. This is an art of copying practised by the
smith. In order to fashion his iron and steel into the various
forms demanded by his customers, he has small blocks of steel
into which are sunk cavities of different shapes; these are
called swages, and are generally in pairs. Thus if he wants a
round bolt, terminating in a cylindrical head of larger diameter,
and having one or more projecting rims, he uses a corresponding
swaging tool; and having heated the end of his iron rod, and
thickened it by striking the end in the direction of the axis
(which is technically called upsetting), he places its head upon
one part of the lage; and whilst an assistant holds the other
part on the top of the hot iron, he strikes it several times with
his hammer, occasionally turning the head one quarter round. The
heated iron is thus forced by the blows to assume the form of the
mould into which it is impressed.

124. Engraving by pressure. This is one of the most beautiful
examples of the art of copying carried to an almost unlimited
extent; and the delicacy with which it can be executed, and the
precision with which the finest traces of the graving tool can be
transferred from steel to copper, or even from hard steel to soft
steel, is most unexpected. We are indebted to Mr Perkins for most
of the contrivances which have brought this art at once almost to
perfection. An engraving is first made upon soft steel, which is
hardened by a peculiar process without in the least injuring its
delicacy. A cylinder of soft steel, pressed with great force
against the hardened steel engraving, is now made to roll very
slowly backward and forward over it, thus receiving the design,
but in relief. The cylinder is in its turn hardened without
injury., and if it be slowly rolled to and fro with strong
pressure on successive plates of copper, it will imprint on a
thousand of them a perfect facsimile of the original steel
engraving from which it was made. Thus the number of copies
producible from the same design may be multiplied a
thousand-fold. But even this is very far short of the limits to
which the process may be extended. The hardened steel roller,
bearing the design upon it in relief may be employed to make a
few of its first impressions upon plates of soft steel, and these
being hardened become the representatives of the original
engraving, and may in their turn be made the parents of other
rollers, each generating copperplates like their prototype. The
possible extent to which facsimiles of one original engraving may
thus be multiplied, almost confounds the imagination, and appears
to be for all practical purposes unlimited.

This beautiful art was first proposed by Mr Perkins for the
purpose of rendering the forgery of bank notes a matter of great
difficulty; and there are two principles which peculiarly adapt
it to that object: first, the perfect identity of all the
impressions, so that any variation in the minutest line would at
once cause detection; secondly, that the original plates may be
formed by the united labours of several artists most eminent in
their respective departments; for as only one original of each
design is necessary, the expense, even of the most elaborate
engraving, will be trifling, compared with the multitude of
copies produced from it.

125. It must, however, be admitted that the principle of
copying itself furnishes an expedient for imitating any engraving
or printed pattern, however complicated; and thus presents a
difficulty which none of the schemes devised for the prevention
of forgery appear to have yet effectually obviated. In attempting
to imitate the most perfect banknote, the first process would be
to place it with the printed side downwards upon a stone or other
substance, on which, by passing it through a rolling-press, it
might be firmly fixed. The next object would be to discover some
solvent which should dissolve the paper, but neither affect the
printing-ink, nor injure the stone or substance to which it is
attached. Water does not seem to do this effectually, and perhaps
weak alkaline or acid solutions would be tried. If, however, this
could be fully accomplished, and if the stone or other substance,
used to retain the impression, had those properties which enable
us to print from it, innumerable facsimiles of the note might
obviously be made, and the imitation would be complete. Porcelain
biscuit, which has recently been used with a black lead pencil
for memorandum books, seems in some measure adapted for such
trials, since its porosity may be diminished to any required
extent by regulating the dilution of the glazing.

126. Gold and silver moulding. Many of the mouldings used by
jewellers consist of thin slips of metal, which have received
their form by passing between steel rollers, on which the pattern
is embossed or engraved; thus taking a succession of copies of
the devices intended.

127. Ornamental papers. Sheets of paper coloured or covered
with gold or silver leaf, and embossed with various patterns, are
used for covering books, and for many ornamental purposes. The
figures upon these are produced by the same process, that of
passing the sheets of paper between engraved rollers.





Next: Of Copying By Stamping

Previous: Of Copying By Casting



Add to del.icio.us Add to Reddit Add to Digg Add to Del.icio.us Add to Google Add to Twitter Add to Stumble Upon
Add to Informational Site Network
Report
Privacy
SHAREADD TO EBOOK


Viewed 1124