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Full text of "Metallurgy Of Cast Iron"

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UTILITY    OK   T1-1K   TEST   T.AU,    KTC.                    529
Where there are many duplicates, as in the manufacture of ear wheels, pipes, etc., we can, by breaking a few castings, and test liars that have been, cast out of the same ladle of iron, obtain a very fair base as a standard for future comparisons of what may be expected in the castings themselves from test bars from future mixtures. 'This is not saying that single castings made of the same pattern, cast at different times,k could not have any comparative knowledge imparted of their strength, etc., by reason of using- a proper test bar, east with the same ladle of iron. If a single casting stands desired usage and the builder or buyer has a record of test bars that was poured of the same iron with the easting, he generally can rest fairly assured that, if at any other time he should get another casting made from the same pattern with test bars that would show a similar strength, he would have a casting that would be fairly equal in strength, etc., to the first one made. And again, the u.se of these can often prove protection to builders that have machines broken by claimants for unjust damages, as, for instance, in the case of punch and shear eastings, which are often broken by reason of carelessness on the part of workmen or attempts being made by the proprietors to utilize a machine above the strains guaranteed. For if the builder can prove that previous eastings, which had tests recorded from test bars, had stood the guaranteed strains to compare closely with the easting that: broke, he cannot be far out of the way in maintaining the position that the close comparison of all his test bar records justified him in assuming* that, all eastings made from that one pattern should be closely alike, for the reason that they can be classed under the head of467 and 484, if they have not drawn              '1