Factory and industrial management . ng. This exceedingly important result is, in the case of suchsmall tools, rather difficult of attainment by reason of the frequentand sometimes considerable fluctuations in the interior of a gas fur-nace, which latter is otherwise undoubtedly better adapted to theheating of high-speed steel tools than any other type. With largetools these fluctuations, arising from variations in pressure, areas ofopenings, and the like causes, make little difference on account ofthe considerable length of time required to affect a large mass. In thecase of small ones however
Factory and industrial management . ng. This exceedingly important result is, in the case of suchsmall tools, rather difficult of attainment by reason of the frequentand sometimes considerable fluctuations in the interior of a gas fur-nace, which latter is otherwise undoubtedly better adapted to theheating of high-speed steel tools than any other type. With largetools these fluctuations, arising from variations in pressure, areas ofopenings, and the like causes, make little difference on account ofthe considerable length of time required to affect a large mass. In thecase of small ones however, where the time of heating is compara-tively short, any such fluctuation may be sufficient to affect the qualityof the tools. This difficulty also has been overcome in the past by theuse of the lead bath and muffles, wliich however have the disadvan-tages already mentioned. The distortion sometimes occurring in long and slender or spe-cially shaped tools, when heated in the ordinary gas or coke fires. 730 THE ENGINEERING THE BARIUM PROCESS LEAVES THE SURFACE OF A TOOL ABSOLUTELY UNIMPAIRED, IF IT BE QUENCHED IN OIL. The only difference in the appearance of hardened and unhardened tools is a very slight darkening of the color, so slight as to be nnnoticeable except when compared with an untreated surface. causes trouble. This is avoidable in part in all cases, and wholly inthe case of straight tools, by heating them suspended in a cylindricalgas furnace. Ever since the advent of the new steels, these difficultieshave suggested the need for some method of heating tools of thissort which would do away entirely with oxidizing, warping, refin-ishing, and the like troubles. In Europe particularly, experimentswere carried on from time to time with the purpose of developingsuch a method, and with some success. It was in Germany, I believe, that a bath of melted barium chlo-ride was first used to replace the lead bath; and I am told that in theshops of the Ludwig Loewe Co.,
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