Sheet metal

“ The malleability and ductility of metals lie at the basis of the work of the gold- and silver-smiths at one extreme, and of the boiler-maker at the other. Sheet metals can be made to assume almost any shape under the hammer, or by pressure, provided they are subjected to annealing to restore the property of malleability. The most awkward shapes, involving excessive extensions of metal, are produced by drawing processes between dies of iron and steel in power presses. ”

“ Sheet brass and copper may be purchased at large hardware stores or supply houses for thirty cents a pound, and the sheets or panels can be cut there with the shears to the exact size required. For the average work, metal not more than one-sixteenth of an inch thick will be found easy to handle ”

“ CHAPTER VI. METAL SPINNING. Spinning sheet metal into various forms is another kind of work which can be done in the foot lathe, and it is here that the amateur can show his taste and dexterity.
The process consists in forming a blank, like this engraving, into an ornamental base for a lamp, or an oil cup; in fact, any thing whatsoever. All that is requisite is to have a fac simile, in wood, of the shape you wish to make. This is bolted or otherwise made fast to the face plate, and the blank is then set up against it, and held as the cylinder head, shown in Fig. ”

“ Thin sheets of metal of different kinds can be used to great advantage in decoration; and it would seem hardly possible that strips of stovepipe iron, sheet-lead, brass, copper, and zinc could be employed to form such artistic edgings to wood boxes and bits of furniture as may be seen in the following illustrations. ”

“ The sheet is then fed forward, and the slitting and stretching operation is repeated in such a manner that the slits are in every case made back of the portion unsevered by the preceding operation, or, in other words, as the specification states, the slits and unsevered portions alternate in position in each successive operation, the bends given to the severed portions or strands being in direction at right angles to the plane of the sheet, there is no contraction in the length of the metal, and the expansion is obtained by the stretching, distension, or elongation of the severed strand. ”

“ A metallic alloy is made of tin, lead, bismuth, and antimony, which melts at a moderate heat. This is poured into the sheet-iron tray, and after it is cooled and concreted, it is inverted, and shaken off from the model bars, so as to form a mass of metal perforated throughout with tubular cavities, corresponding to the intended pencil-pieces. The paste is introduced by pressure into these cavities, and set aside to dry slowly. When nearly dry, the pieces get so much shrunk that they may be readily turned out of the moulds upon a cloth table. ”

“ Sheet-lead forms a much heavier roof covering than zinc, but it lasts a great eal longer and more easily withstands the attacks of impure air. Lead must be laid on a close boarding, for Lead its great ductility prevents it from spanning even the smallest spaces without bending and giving way. This characteristic of the metal, however, conduces largely to its usefulness, and enables it to be dressed and bossed into awkward corners without the necessity of jointing. ”

“ By this means, a piece of sheet-iron, which, as a plain flat surface, has no strength but in its tenacity, becomes a series of continued arches abutting against each other; and the metal, by this new position, acquires increased strength. Iron so furrowed is deemed preferable to common sheet-iron for covering a flat-roof, because the furrows will collect the water and carry it more rapidly to the eaves. ”

“ The latter are made in one pair of dies from red-hot steel by stamping the plastic metal into the die or moulding red-hot iron in a mould made of compressed sand; the pressings are formed from sheet steel between dies, but the metal is treated cold and usually has to pass through more than one pair of dies before it assumes the desired shape. ”

“ MOCK GOLD Fuse together 16 parts of copper, 7 of platinum, and 1 of zinc. When steel is alloyed with 1/500 part of platinum, or with 1/500 part of silver, it is rendered much harder, more malleable, and better adapted for all kinds of cutting instruments. Note.—In making alloys, care must be taken to have the more infusible metals melted first, and afterwards add the others.
151. BRITANNIA METAL Take 4 parts of brass, and 4 parts of tin; when fused add 4 parts of metallic bismuth, and 4 parts of metallic antimony. ”

“ Upon analysis the brass was found to contain 70%-75% copper, 20%-30% zinc, and other trace elements. The blades, cocking levers, and button releases of lancets and scarificators were found to be made of ferrous metal (iron or steel) . In addition to the typical brass pieces, a number of “white metal” pieces were analyzed. (The term “white metal” is used to designate any undetermined silver-colored metal alloy.) Those white metal pieces dating from the eighteenth century (a Swiss or Tyrolean fleam and an English veterinary spring lancet) were found to be composed entirely of ferrous metal. ”

“ Metal itself implied metal-working; and metal-working brought about, not only the arts of smelting and casting, but also endless incidental arts of design and decoration. The bronze hatchets, for example, to take our typical implement, begin by being mere copies of the stone originals; but, as time goes on, they acquire rapidly innumerable improvements. First, metal is economized in the upper part which fits into the handle, while the lower or cutting edge is widened out sideways, so as to form an elegant and gracefully curved outline for the whole implement. ”

“ We have, secondly, work in bronze, iron, gold, and [Pg 97] other metals; in which the laws of structure are still more definite.
All kinds of twisted and wreathen work on every scale become delightful when wrought in ductile or tenacious metal; but metal which is to be hammered into form separates itself into two great divisions—solid, and flat.
a. In solid metal-work, i.e., metal cast thick enough to resist bending, whether it be hollow or not, violent and various projection may be admitted, which would be offensive in marble ”

“ The different metals are malleable, ductile and tenacious in the following order; white metal or britannia, aluminum, zinc, copper, low brass, high brass, German silver, steel, tin plate. White metal does not harden in spinning, but it requires special skill in handling, or the metal will be of very uneven gage. The best metal for an amateur to start on is copper, as it is both tenacious and ductile, and will stand much abuse in the fire and on the lathe. ”

“ But in those forms where curving must take place in different directions the layers or fibres of metal are made to glide over one another, extension taking place in some layers but not in others, and this goes on without producing much reduction in the thickness. This is only possible with malleable and ductile metals and alloys. As a general rule it is restricted to metals which are not cast, for, with some slight exceptions, it is impossible to produce relative movements of the layers in cast iron, steel or cast brass. ”

“ But steel of cementation, however carefully made, is never quite equable in its texture. Steel possessing this latter quality is made, by fusing bars of blistered steel, in a crucible placed in a wind furnace. When the fusion has been completed, the liquid metal is cast into small bars or ingots, which are known in commerce by the name of cast steel. Cast steel is harder, more elastic, closer in texture, and capable of receiving a higher polish than common steel.
7. Steel is also made directly from cast iron, or at once from the ore. ”

“ There is little doubt that at some time or other every known metal was tried experimentally in the mixture; but, from the earliest days of letter-casting, lead and tin have always been recognised as the staple ingredients of the alloy; the hard substance being usually either iron, bismuth, or antimony.
Turning now from type-casting appliances to the early types themselves, we are enabled, thanks to one or two recent discoveries, to form a tolerably good idea as to their appearance and peculiarities. ”

“ Steel is not found native, but is a compound of iron and carbon and is produced artificially. The great value of steel lies in the fact that it can be made so hard that it can cut and shape almost every other substance known to man, and yet this very quality of hardness can be so modified as to make the metal capable of cutting and otherwise shaping itself. Steel can be made nearly as hard as the diamond, or so soft that it can be cut, bent, or hammered into this shape or that, rolled into sheets, or drawn out into the finest wire. ”

“ The metals thus united may be either the same or dissimilar; but the uniting metal must always have an affinity for both. Solders must be, therefore, selected in reference to their appropriate metals. Thus tin-plates are soldered with an alloy consisting of from 1 to 2 parts of tin, with 1 of lead; pewter is soldered with a more fusible alloy, containing a certain proportion of bismuth added to the lead and tin; iron, copper, and brass are soldered with spelter, an alloy of zinc and copper, in nearly equal parts ”

“ OXY-ACETYLENE WELDING AND CUTTING, ELECTRIC AND THERMIT WELDING
CHAPTER I METALS AND THEIR ALLOYS--HEAT TREATMENT
THE METALS
Iron.--Iron, in its pure state, is a soft, white, easily worked metal. It is the most important of all the metallic elements, and is, next to aluminum, the commonest metal found in the earth.
Mechanically speaking, we have three kinds of iron: wrought iron, cast iron and steel. Wrought iron is very nearly pure iron; cast iron contains carbon and silicon, also chemical impurities ”

“ Next prepare the metal holder. This may be made of brass or copper and need not be of very heavy gauge-No. 22 is plenty heavy enough. The easiest way to get the shape of the metal is to make a paper pattern of the development. The illustration shows how this will look and the size of the parts for the back dimensioned above. Trace this shape on the metal with the carbon paper and cut it out by means of metal shears. Polish the metal, using powdered pumice and lye, then with a nail, punch the holes, through which small round-head brass screws are to be placed to hold the metal to the wood back. ”

“ But since modern methods of manufacturing have been adopted, tons of metal, which would have been classed as iron if judged by the cooling test, are at present known as mild or soft steel.
Steel may properly be defined as an alloy of iron with carbon, the latter not exceeding 1.8 per cent; the materials are completely fused and poured into molds, allowed to cool, and then rolled into shape. In the processes of making wrought iron the materials are only partly fused and are not cast into molds, but are taken out of the furnace in a soft, pasty condition suitable for immediate working. ”

“ Power Presses in Metal Working.
From glass let us now turn to metals. It is their tenacity that chiefly gives them value; this tenacity is usually accompanied by a hardness which disposes us to regard nickel, for example, as of a solidity quite unyielding. But the coins in our pockets prove that under the pressure of minting machinery they are as impressible as wax. In molds and dies, each the counterpart of the other, brass, bronze, iron, steel, and tin-plate take desired forms as readily as if paste. Solid though these metals appear they yield under severe stress with a semi-fluid quality. ”

“ A good type-foundry is always provided with several furnaces, each surmounted with an iron pot containing the melted alloy, of 3 parts of lead and 1 of antimony. Into this pot the founder dips the very small iron ladle, to lift merely as much metal as will cast a single letter at a time. Having poured in the metal with his right hand, and returned the ladle to the melting-pot, the founder throws up his left hand, which holds the mould, above his head, with a sudden jerk, supporting it with his right hand. It is this movement which forces the metal into all the interstices of the matrix ”

“ Steel for guns and armor is made in the open-hearth furnace where the quality of the metal may be regulated to a nicety. Gun tubes are cast in vertical molds and during the cooling of the ingot it is subjected to pressure so as to prevent segregation and the forming of “pipes.” Pipes are cavities that are liable to form in the center of the ingot due to contraction during cooling. Steel, as we have learned, is not pure iron, but an alloy, and the various constituents have different temperatures of solidifying, consequently they exhibit a tendency to [324] segregate. ”

“ In olden times only the upper horizon of copper deposits were worked in all districts. In these, as we know, the ores are mostly oxides (with native copper) . Such ores are easily worked and yield largely.
3. In regard to the mixing of metals, the metallurgists everywhere must have soon learned by experience that the metal remained soft and red when too little tin was added, while too much tin made it light colored and lustrous, but, at the same time, very brittle. Hence, we find that among all peoples the alloys used for weapons contain from 6 to 16, or, more closely, 8 to 12 per cent. ”

“ It is a white cast iron, made by a surcharge of ore in the furnace. If the white colour becomes less clear and turns bluish, if its fracture be contorted, and contains a great many empty spaces or air-cells, the metal takes the name of cavernous-floss, or tender-floss. The whitest metal cannot be employed for casting. When the white is mixed with the gray cast iron, it becomes riband or trout cast iron. ”