Canadian foundryman (1917) . OR CRITI-CAL TEMPERATURES THE fact that steel loses its magneticproperties on attaining the critical tem-perature forms thebasis on which hasbeen designed theCrit-Point, an in-strument which infal-libly indicates the in-stant when a body ofsteel has attained thedecalescent or harden-ing point. Tn heat treating in-stallations of t h ousual type, entire re-liance is frequentlyplaced on the per-manent accuracy of the pyrometer,which is subject to \ariation throughdeterioration of the thermo-elements;the element of time demands con-sideration so that the steel may assu
Canadian foundryman (1917) . OR CRITI-CAL TEMPERATURES THE fact that steel loses its magneticproperties on attaining the critical tem-perature forms thebasis on which hasbeen designed theCrit-Point, an in-strument which infal-libly indicates the in-stant when a body ofsteel has attained thedecalescent or harden-ing point. Tn heat treating in-stallations of t h ousual type, entire re-liance is frequentlyplaced on the per-manent accuracy of the pyrometer,which is subject to \ariation throughdeterioration of the thermo-elements;the element of time demands con-sideration so that the steel may assume a uniform condition at the required tem-perature; the personal factor appears indetermining whether the two foregoingconditions have yielded the result de-sired. Trouble due to misapplication in anyof these respects is entirely eliminatedby the instrument referred to, whichindicates the critical point, not as adegree of temperature, but as a non-magnetic state. The instrument consistsof a contact box containing magnet and. PNEUMATIC POWER SQUEEZER MOLDING MACHINE. coils, mounted on one end of a rod pro-vided with handles and heat shield. Theother end of the rod carries a magneticflux meter, the needle of which indicatesthe gradual approach of the steel to thenon-magnetic, or critical point. Imme-diately contact is made with the steelin the furnace through the medium ofthe magnetic coils, the needle indicatesthe degree of magnetism in the metal,all knowledge of the actual temperaturebeing irrelevant, so far as the indicationof the critical temperature is makers of this instrument are theGibb Instrument Co., Pittsburgh, Pa. DIAGRAM of theCRIT-POINT
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