Hardening, tempering, annealing and forging of steel; a treatise on the practical treatment and working of high and low grade steel .. . FIG. 96.—SPECIAI, PORMBD BUTT MILL. FIG. 97.—^END MILLS. plunged into oil; and as the oil does not abstract the heat as fastas the water, the steel has more time to adjust itself to molecularmotion and there is less tendency to crack. Again, the oil lefton the outside of the tool serves as an indicator for determiningthe temperature at which to reheat the steel to give the propertemper. As the tool is not completely cooled in the oil, very little. FIG. 98.—^S
Hardening, tempering, annealing and forging of steel; a treatise on the practical treatment and working of high and low grade steel .. . FIG. 96.—SPECIAI, PORMBD BUTT MILL. FIG. 97.—^END MILLS. plunged into oil; and as the oil does not abstract the heat as fastas the water, the steel has more time to adjust itself to molecularmotion and there is less tendency to crack. Again, the oil lefton the outside of the tool serves as an indicator for determiningthe temperature at which to reheat the steel to give the propertemper. As the tool is not completely cooled in the oil, very little. FIG. 98.—^SPFJCIAL MILL. external heat is required to draw it. In fact, the drawing of thetemper really begins immediately upon removing the tool fromthe water bath. Lard oil is the best to use in tempering in this way, and it hasbeen found that the oil commences to show a very faint smoke atabout the same temperature as a light straw; the proper tempermay be considered as reached when the smoke is seen comingfrom all parts of the tool. 152 HARDENING, TEMPERING AND ANNEALING. Tools tempered in this way will prove to be harder and yettougher than those tempered according to the ordinary cutters from Yx inch in diameter up have been tempered
Size: 3158px × 791px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidhardeningtem, bookyear1903
