Joseph Gregory Horner

“ Machine-moulding.—There is a development of modern methods of founding which is effecting radical changes in some departments of foundry practice, namely, moulding by machines. The advantages of this method are manifold, and its limitations are being lessened continually. There are two broad departments between which machine-moulding is divided. One, of less importance, is that of toothed wheels ”

“ Core-making is a special department of foundry work, often involving as much detail as the construction and moulding of patterns. Two perfectly plain boxes are shown in figs. 8 and 9, in both of which provision exists for removing the box parts from the core after the latter has been rammed. Core boxes are jointed and tapered, and often have loose pieces within them, and also prints, into the impressions of which other cores are inserted. ”

“ Gear-wheel moulding machines are essentially a special adaptation of the mechanism of the dividing engine, by means of which, instead of using a complete pattern of a toothed wheel, two or three pattern teeth are used, and the machine takes charge of the correct pitching or division of the teeth moulded therefrom, leaving to the moulder the work only of turning the handle of the division plate, and ramming the sand around the pattern teeth. ”

“ The highest economies of machine-moulding are obtained when (1) several small patterns are mounted and moulded at once on a single plate (fig. 10) ; (2) when top and bottom parts of a mould are produced on different machines, carrying each its moiety of the pattern; (3) when the machine and pattern details are simplified so much that the labour of trained moulders is displaced by that of unskilled attendants who are taught in a month or two the few simple operations required. That is the direction in which repetitive casting is now rapidly tending. ”

“ The purpose of chill-casting is to produce a surface hardness in the metal.
The shrinkage of metal is a fact which has to be taken account of by the pattern-maker and moulder. A pattern and mould are made larger than the size of the casting required by the exact amount that the metal will shrink in cooling from the molten to the cold state. ”

“ Its variable amount has to be borne in mind in making light and heavy-castings, and castings with or without cores, for massive cores retard shrinkage. It is also a fruitful cause of fracture in badly proportioned castings, particularly of those in steel. Brass is less liable to suffer in this respect than iron, and iron much less than steel. ”

“ Patterns have to be constructed strongly. They are generally of wood, and they thus require skill in the use of woodworking tools and the making of timber joints, together with a knowledge of the behaviour of timber, &c. ”

“ All heavy marine engine cylinders are thus made by sweeping, and all massive cores for engine cylinders and large pipes, besides much large circular and cylindrical work, as foundation cylinders, soap pans, lead pans, mortar pans, large propeller blades, &c. ”