THE A. K. A. COMMITTEE'S REPORT.
2 per cent, in silicon, or where the silicon is lower and the proportion of scrap is rather large.
For roll irons, whether chilled or sand, and car wheel metals, a 2*^-inch diameter bar is recommended; that is, for all irons below i per cent, silicon, and which may therefore be classed as the chilling irons. This would include also all white irons.
The method of moulding the test bars we would recommend is given herewith, and is such as will be readily understood by every practical foundryman. Both tensile and transverse bars are shown in the same flask. The elevation shows the tensile bar at A and the transverse one at B. The core C is used with the tensile bar in order to ram it on end. The core box is seen at Fig. 150. In starting to mould up the bars the dried core is set on the bottom board, and then the pattern as seen at D placed into the hole in the top of
FIG. 150.----CORE BOX, TF.NSILE TEST 1'ATTERN.
the core and let rest on its bottom. Now ram up the bar with green sand in the usual manner. The plan shows four bars. This can be modified as desired. If no tensile bars are wanted, the core is avoided altogether. Two bars may be poured at a time, or four, or more, by simply connecting the pouring basin E E as shown by the dotted line around G, in which case, however, the basin E E should be made much smaller. At least three bars of a kind should be made for a given test. The accompanying sketches give allning from 2 per cent, in silicon upward, or from 1.75 per cent, silicon upward where but little scf ap is in the mixture.