ACTA TECHNICA CORVINIENSIS - Bulletin of Engineering

ACTA TECHNICA CORVINIENSIS – BULLETIN of ENGINEERINGv c[m/min]Tab. 3 Values of calculated tool life for theexperimental AC 300G cutting insertVB Crit[mm]t A[min]t B[min]VB A[mm]VB B[mm]T[min]285.5 30.4 40.4 0.19 0.23 32.9348.3 0.20 20.1 24.1 0.19 0.23 21.1434.54.0 6.4 0.19 0.21 5.2The measurement was performed at threecutting speeds. Subsequently, extrapolation wascarried out with the aid of the regression line forvalues in a range of 250 – 500 m/min and theinterval reliability was determined for thisextended cutting speed band, see Table 4.Student’s distribution was used for thecalculation, for the significance level of t α =3.078, α = 90%, f = 1 [4,5].average cutting speeds for three sets of thecutting speeds are shown in Table 5.Tab. 5 Average values of cutting speeds v c for theexperimental AC 700G cutting insertAC 700G;v c1 [m/min] v c2 [m/min] v c3 [m/min]283.0 353.9/345.0 445.7Based on the relation VB = f (t), the value of theflank wear criterion VB Crit was set to VB Crit = 0.30mm for AC 700G. The dependence of the wearon time VB = f (t) is shown in Figure 4.When machining the AC 700G CCI, at the speedof v c2 = 353.92 m/min and time t = 17.2 minfrom the test start, the cutting edge broke at thepeak of the CCI. Then it was experimented withavarage cutting speed v c2 = 345.0 m/min.Tab. 4 Corresponding intervals of reliability for theexperimental AC 300G cutting insertv c [m/min] L 1 (-) L 2 (+) T [min]250.0 17.4 272.7 68.8285.5 14.5 101.2 32.9300.0 13.2 71.3 30.7348.3 8.5 29.6 21.1400.0 3.9 18.8 8.6434.5 2.2 16.1 5.2500.0 0.8 13.3 3.2Fig. 4 Graphic dependence of VB=f(t) for theexperimental AC 700G cutting insertFig. 3 Experimental relationship between tool lifedata and different cutting speeds for the experimentalAC 300G cutting insertIn Figure 3 you can see the dependency of thedurability on the cutting speed T = f(v c ) togetherwith the confidence band for the linearregression dependence.AC 700G CCIWhen evaluating the experiment performedwith AG 700G CCI we were following the samesteps as for the AC 300G CCI. The countedTab. 6 Values of calculated tool life for theexperimental AC 700G cutting insertv c VB Crit t A t B VB A VB B T[m/min] [mm] [min] [min] [mm] [mm] [min]283.00 14.20 35.50 0.29 0.33 19.50345.00 0.30 10.50 20.10 0.28 0.32 15.30445.703.25 7.00 0.29 0.31 5.10The durability counted for the CCI with the AC700G is listed in Table 6. To compare the CCIs wechose the value of the flank wear criterion VB Crit= 0.30 mm for the AC 700G. The intervalreliability for the extended cutting speed bandfor the AC 700G is shown in Table 7.Tab. 7 Corresponding intervals of reliability for theexperimental AC 700G cutting insertv c [m/min] L 1 (-) L 2 (+) T [min]250.0 11.4 90.8 32.2283.0 10.3 47.5 19.5300.0 9.7 35.7 18.6345.0 7.4 20.1 15.3400.0 4.3 14.3 7.8445.7 2.5 12.6 5.1500.0 1.4 11.5 4.0782010/Fascicule 2/April­June /Tome III