. Transactions. perfection of the process for die-casting aluminum andits alloys. The importance of this achievement as an aid to winningthe war is best demonstrated by the fact that at least 95 per cent, of thedie-cast parts used directly or indirectly as materials of war were madefrom an aluminum-base alloy. Of thege castings, only a very smallpercentage could have been produced successfully in 1914. CHARLES PACK 583 Investigations of the casting properties of metals and alloys in thepast have been generally limited to sand castings; few data areavailable as to the casting properties of meta
. Transactions. perfection of the process for die-casting aluminum andits alloys. The importance of this achievement as an aid to winningthe war is best demonstrated by the fact that at least 95 per cent, of thedie-cast parts used directly or indirectly as materials of war were madefrom an aluminum-base alloy. Of thege castings, only a very smallpercentage could have been produced successfully in 1914. CHARLES PACK 583 Investigations of the casting properties of metals and alloys in thepast have been generally limited to sand castings; few data areavailable as to the casting properties of metals or alloys in metallicmolds. Just what constitutes a good die-casting alloy is a subject ofunusual interest. A few of the important requirements, outside of theusual physical properties demanded of alloys, are: Melting —The successful die-casting machine in every instanceis constructed of iron, in one form or another. The melting point ofthe alloy must be such that it will melt readily in an iron Fig. 6.—Machine with die enclosed in vacuum chamber. Solvent Action.—The solvent action of the alloy on iron must not betoo great. Molten aluminum dissolves iron very rapidly and analysesof aluminum die castings on the market will show an iron content of from1 to 3 per cent., due to the solvent action. Fortunately, there isno serious objection to the presence of iron in aluminum casting the aluminum absorb much above 3 per cent, iron, the meltingpoint becomes too high and the alloy becomes viscous and unsuitable formaking castings. Elongation.—The elongation of the metal is of vital importance indetermining the die-casting properties of an alloy. Not only is itdesirable to know the elongation of the alloy when cold, but it is ofgreater importance to determine the elongation at various temperaturesranging from the melting point of the alloy down to normal tem-perature. The reason for this becomes apparent when the physicalphenomena of the die-casting
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
