472 FOUNDING; FOUNDRY 



Grains of sand are so irregular in shape themselves that they leave innumerable 

 irregular spaces between them, and those intervals form a network of channels which 

 permit the rapid escape of the gases, which are so violently generated by the contact 

 of hot metal falling upon wet sand. 



Machine Castings. Every year, engineers order castings to be prepared of more 

 difficult and complicated forms, and with greater perfection of surface than they have 

 required before. 



The reason of this is, that with the progress of the mechanical arts larger and 

 stronger machines are continually being introduced. In these machines greater steadi- 

 ness of cast-iron framework is necessary than can conveniently be obtained when the 

 frame is made out of a number of pieces of iron cast separately and then bolted 

 together. It would be impossible to mould large frames with pieces projecting on all 

 sides (prepared to receive the moving parts of the machines), and jutting out in contrary 

 directions, in any flasks filled with wet sand, for the pattern never could be removed 

 without destroying the impression. To meet these difficulties, the modern ironfounder 

 has had to follow those plans which were first proved practicable to those who have 

 devoted themselves to casting bronze statues. In founding, as in so many other 

 branches of manufacture, the discoveries made in prosecuting the fine arts have been 

 advantageously adopted by those engaged in works of utility. 



False Cores. The introduction of the drawbacks, or false cores, made of sand 

 pressed hard (and admitting of taking to pieces by joints, at each of which a layer of 

 parting sand is prepared), using for figure casting, enables the moulder to work at his 

 leisure, without fearing that his mould may tumble to pieces, and also enables him to 

 fashion these drawbacks or cores into the most complicated forms, with the power to 

 remove them while the pattern is removed, and build them up again round the empty 

 space (formerly occupied by the pattern) with the greatest facility and accuracy. 



The workmen, whose occupation is to knead the sand into the forms required by the 

 founder, are termed moulders, and they form a very numerous body of mechanics, de- 

 manding and receiving high wages. 



The moulder has often only his sand, his flasks, cranes, and a few simple tools (for 

 smoothing rough places, and for repairing the places in the sand where the mould has 

 broken away during the lifting of the pattern) ; he has to make proper arrangements 

 for the exit of the atmospheric air which leaves the mould as the fluid metal takes its 

 place ; and he is expected to produce an exact copy in metal from any pattern, simple 

 or complicated which may be brought before him. 



It will be evident that to produce a good result with such imperfect appliances as 

 the ordinary moulder uses, a skilful workman must be employed, and time expended 

 in proportion the difficulty of the operations to bo performed. 



"Where only a few impressions from a model are required, it is not worth while to 

 spend money in making expensive patterns, or providing those appliances which may 

 enable patterns to be moulded with facility and little skill ; but where thousands of 

 castings are wanted of one shape, it is expedient to spend money and skill on patterns 

 and tools, and reduce the work of the moulder to its minimum. 



Management. The best managed foundry is not that in which good castings are 

 obtained by the employment of skilled workmen at a great expense, and without 

 trouble or thought on the part of the principal, but rather that in which the patterns 

 have been constructed with a special reference to their being cast with the minimum 

 of skill and the maximum of accuracy. It is only by the forethought and calculation 

 of the manager that subsequent operations can be reduced to their smallest cost : and 

 in the foundry, as in all other manufactories, the true principles of economy are only 

 practised where the head-work of one person saves the manual labour of a largo 

 number. 



Improvements. The attention of founders has been turned 1st, to the methods 

 by which the labour of making moulds in sand might be reduced ; 2nd, to the intro- 

 duction of improvements in the mode of constructing patterns and moulds ; and 3rd, 

 to the manufacture of metallic moulds for those purposes for which they could be 

 applied. A great progress has been made during the last twenty years in thcso 

 different directions. 



Machine Moulding. In the large industry carried on for the production of 

 cast-iron pipes for the conveyance of water and gas, machinery has been applied so 

 that the operation of pipe-moulding is performed almost without manual labour, with 

 groat rapidity and precision. The cost of pipes at the present time is only about 21. 

 per ton above the value of pig-iron, out of which they are made ; a sum very small 

 when it is considered that the iron has to bo re-melted, an operation involving both a 

 cost of fuel and a loss of 5 to 20 per cent, of the iron in the cupola. An ingenious 

 machine for moulding in sand, spur and bevel wheels of any pitch or diameter has 

 been employed in Lancashire ; the advantage bcjng that tho machine moulding tool 



