Flank wear data were collected in a series of turning tests using a coated carbide tool on hardened alloy steel at a feed of 0.30 mm/rev and a depth of 4.0 mm. At a speed of 100 m/min, flank wear = 0.12 mm at 1 min, 0.27 mm at 5 min, 0.45 mm at 11 min, 0.58 mm at 15 min, 0.73 at 20 min, and 0.97 mm at 25 min. At a speed of 155 m/min, flank wear = 0.22 mm at 1 min, 0.47 mm at 5 min, 0.70 mm at 9 min, 0.80 mm at 11 min, and 0.99 mm at 13 min. The last value in each case is when final tool failure occurred.
(a) On a single piece of linear graph paper, plot flank wear as a function of time for both speeds. You may use Excel to help yourself to plot the curve. Using 0.75 mm of flank wear as the criterion of tool failure, determine the tool lives for the two cutting speeds. From the plot, determine the values of nand C in the Taylor Tool Life Equation.
(b) As a comparison, calculate the values of n and C in the Taylor equation solving simultaneous equations.