Casting (manufacturing)

“ The pattern when cast is “laid out” on a hollow hemisphere of iron filled with pitch, and the irregularities of the casting removed by hand tools, files, rasps, and knives. In the case of figures, such as cupids, &c. forming ornaments for candelabra, the various limbs have often to be modelled in separate “cores,” [111] which are afterwards baked hard, and put together like a puzzle-map, imbedded in the sand of the mould previous to casting. This requires great skill to effect successfully, and an experienced “reverser” is a man of mark in the factory.
Fork. Vent Wire. Sleeking Tool. ”

“ With small articles in brass, metal patterns are used. For gold articles, such as wedding rings, an iron frame is used, filled with the finest red sand. For small gold work, the cuttle fish bone is used as a mould, the pattern being pressed in the same manner as in sand. [46] A special feature in the process of casting in our district is the production of “chilled” castings for rolls. The mould for the barrel part of the roll is a heavy cylindrical casting of iron truly bored out to a size sufficient to allow of the roll being turned to the required size. ”

“ Casting is in the form of sheets, rods, tubes, or special forms suitable for the production of buckles, jewelry, and other small products. Molds of complicated shape cannot be used, which means that most articles if produced of cast resin must be produced from standard shapes by subsequent working. ”

“ The caster having placed the matrix in the bottom of the mould, commences the operation of casting by pouring the metal into the mould with a small ladle. This he performs with his right hand, while with the other he throws up the mould with a sudden jerk; then, with both hands he opens it, and throws out the type. All these movements are performed with such rapidity, that an expert hand can cast about fifty types of a common size in a minute. Some machines have been lately introduced, which operate with still greater rapidity. ”

“ In order to clearly understand the operation of the die-casting machine, let us follow the sequence of events that takes place in producing a casting. Two men are required to operate the machine. In Fig. 27, the operators may be seen in their working positions. The first step is taken by the operator at the left who, with a hand-ladle, dips enough metal for one casting from the melting pot and pours it through nozzle G1 into the goose-neck. ”

“ Castings of less than 0.45 kg and as massive as 11,350 kg have been made on Earth. Commercially, when compared to aluminum die casting, plaster mold casting is considered economical if 1000 parts or less are produced, although production runs up to 2000 parts may also be considered economical if the parts are especially complex. ”

“ It must be remembered, in designing firebacks, that the work is to be carried out by casting and should therefore be of suitable character. Casting is necessary because every time that wrought iron becomes red-hot and cools again it scales, and so loses a considerable thickness of material in a comparatively short time, a disadvantage that does not exist in the cast metal. The design in most cases is treated panel-wise within a raised border, but in the later backs the outline of the design, of the mantling and crest, sometimes formed the edge of the fireback without a containing rim. ”

“ It does not pay to cast rough heavy work that can be made just as efficiently by sand casting. Generally speaking, the greatest saving can be effected by die-casting small pieces which have previously required a large amount of machining to produce. On large plain work the amount of metal required for the casting makes the cost excessive on account of the difference in cost of the metals. If, however, the large work must be finely finished by polishing, etc., it is oftentimes found of advantage to die-cast. Corners, especially those joining thick and thin sections, as at B, Fig. ”

“ The casting-table usually consists of a perfectly smooth cast-iron slab, frequently built up of a number of pieces carefully fitted together, mounted upon a low, massive truck running upon rails, so that it can be readily moved to any desired position in the casting-room. The viscous mass having been thrown on the casting-table, a large and heavy roller passes over it and spreads it out into a sheet. ”

“ No doubt many of you have been troubled with the twisting of some special light casting, and will, perhaps, spend hours in the risky operation of bending an iron pattern so as to get a straight casting. A ladleful of lead and tin, melted in a small gas-furnace, will, in a few minutes, give you a pattern which you can bend and adjust to any required shape. It enables you to make trials to any extent, and get castings with the utmost precision. There is also this advantage, that a soft metal pattern can be cut about and experimented with in a way which no other material admits of. ”

“ In addition, the labor required for operating the casting machines may be classed as unskilled. No matter how intricate and exacting the machine work on a piece has been, and how skillful a workman was required to produce the work when machine-made, the same result may be brought about by die-casting, and usually the work is excelled, and, excluding the die-making, unskilled men can make the parts. ”

“ But there is really no need for more than one casting process. In the twentieth century machine the matrices will be replaced by permanent [Pg 273] type from which, when ranged in the line, an impression will be made by hard pressure on a small bar of soft metal or plastic material. All the impressed bars having been set together in a casting box having the necessary curvature, the final stereo plate for printing from will be taken at once by pouring melted metal on the combined bars. ”

“ All vendors of castings have patterns from which their castings are moulded, and of course they charge, in addition to a profit on the cost of the metal, something for the use of the patterns. The patterns for a founder’s use require certain modifications, which it is unnecessary to explain in detail. ”

“ To enable the founder to prepare a mould for the casting, he must receive a pattern similar to the casting required. Some few exceptions occur, to be noted presently, but the above statement is true of perhaps 98% of all castings produced. The construction of such patterns gives employment to a large number of highly skilled men, who can only acquire the necessary knowledge through an apprenticeship lasting from five to seven years. A knowledge of two trades at least is involved in the work of pattern construction—that of the craft itself and that of the moulder and founder. ”

“ The matrix is rapidly dried on heating surfaces, and then accurately adjusted in a casting machine curved to the exact circumference of the main drum of the printing press, and fitted with a terra-cotta top to secure a casting of uniform thickness. On pouring stereotype metal into this mould, a curved plate was obtained, which, after undergoing a certain amount of trimming at two machines, could be taken to press and set to work within twenty-five minutes from the time at which the process began. ”

“ It is not, however, to be supposed that the possession of such a rule renders it possible for the pattern-maker to discard all further considerations upon the contraction of the casting; because there are others continually stepping in. Such, for example, is the fact that the contraction will not be equal all over, but will be the greatest in those parts where the casting contains the greatest body of metal. ”

“ In this apparatus the metal is fused, injected into ing and the mould, the cast letter turned out, rubbed or planed, first on finishing one side and then on the other, the feet cut out and smoothed, the machine. dressed sides planed alternately, and the finished letter set up on a stick ready for use by the printer. The casting machine and the dressing machine are in reality distinct, though mounted on a com mon frame. The whole is driven by a steam-engine or other prime mover. The casting machine consists of a furnace covered by a shallow pot holding the fused metal. ”

“ In view of the advances that have been made in die-casting, it is singular that there are to-day only5 about a dozen concerns in the business in this country, but as the subject becomes better understood, and the possibilities of the process are realized, the demand for this class of castings will result in many other firms going into the work, and it is not improbable that a large number of factories will install die-casting plants of their own to aid them in producing better work in a more economical way. ”

“ The first essential to good die-casting is a good casting machine. Perhaps the best known types of casting machines are of the familiar33 plunger type, of which there are several varieties, the pneumatic type and the rotary or automatic type. ”

“ TO LARGE CONSUMERS OF FINE LIGHT Malleable Iron Castings, we can offer special inducements in the way of VERY SUPERIOR QUALITY GUARANTEED, and at fair prices. Being ourselves large consumers and requiring the most perfect castings, other work is insured the same attention. ”

“ In some machines pressure is applied to the metal by hand, in others power is used, and in still another class the metal is forced into the dies with compressed air. The provisions for opening and closing the dies vary in the different machines; there are various means employed for cutting the sprue, and the styles of heaters are numerous.
One or two of the largest firms in the die-casting industry have automatic casting machines for turning out duplicate work in large quantities very rapidly. ”

“ Attempts to imitate both processes by casting only, thus dispensing with the cost of finishing, are common, but as they dispense likewise with all beauty in the product, even if they do not substitute varnished and tinted zinc for better metal, their success is commercial only. ”

“ In the first shop the practice consists of planing, chiseling, turning, and the preparation of patterns for casting. The ordinary blacksmithing operations take place in the second shop, and those of casting in the third. ”

“ Some will be found to be done better than others, and one part of the same stack will be done more perfectly than another. The coating on the lead will also differ; some will be smooth, regular, and equal in formation, some will be rough and blistered, and far from uniform. The rough blistered casting is rejected as unfit for white lead making: the workmen call it “dross.” The smooth laminated coating is the one preserved for the after manufacture. ”

“ It now remains to describe the toggles used for operating the cores which form the holes through the three lugs in the casting. One of these toggles, of which there are three, is shown at I, in Fig. 31, and also in Fig. 32.45 These toggles consist of brackets which are attached to the die-plate, and levers which are fulcrumed at the ends of the brackets so that their operation works the core pins. It is necessary to remove these core pins after each casting has been made and position them before another casting can be produced. ”

“ It improves greatly with age. This is the material which is used for casting as will be described later but for plastic work it must be still further thickened. A shallow box may be procured and made water-tight and the slip, when poured into it, will thicken much more rapidly than in the barrel, but it is better to have some shallow plaster dishes as the plaster itself absorbs the water and thickens the clay. ”

“ Substitution is always a factor in deciding whether other techniques should be used instead of casting. Alternatives include parts that can be stamped out on a punch press or deep-drawn, items that can be manufactured by extrusion or by cold-bending, and parts that can be made from highly active metals. ”

“ Articles in Light Metal Work, Fine Castings in Brass, Malleable Iron, &c., Japanning, Tinning, Galvanizing. Welles Specialty Works, Chicago, Ill.
See Boult's Paneling, Moulding, and Dovetailing Machine at Centennial, B. 8-55. Send for pamphlet and sample of work. B.C. Mach'y Co., Battle Creek, Mich.
Wanted—Novel and practical invention, by a reliable house, for manufacturing. Address Post Office, Box 25, Chillicothe, Ohio.
Chester Steel Castings Co. make castings twice as strong as malleable iron castings, at about the same price. See their advertisement on page 125. ”

“ The speed at which die-castings may be produced varies with the size of the castings being made, the composition of the metal being cast, and the style of dies that must be employed. In many cases, in die-casting, separate brass or steel pieces are used, that must be placed in the dies before each operation so that they will be inserted in and become a part of the finished casting. The dies may be difficult of operation on account of draft problems or pins and screws that must be inserted in the dies and removed from each casting before another can be made. ”

“ When, instead of the example now selected, the core of the piece to be cast must go beyond the mould of the external surface, as is the case with a pipe open at each end, the thing is more simple, because we may easily adjust and fix the core by its two ends.
In casting a retort, the metal is poured into the mould set upright. It is important to maintain this position in the two last examples of casting; for all the foreign matters which may soil the metal during its flow, as the sand, the charcoal, gases, scoriæ, being less dense than it, rise constantly to the surface. ”