Issue 70

N. Motgi et alii, Frattura ed Integrità Strutturale, 70 (2024) 242-256; DOI: 10.3221/IGF-ESIS.70.14

Regression statistics

Multiple R

R Square

Adjusted R Square

Standard Error

No. of observations

SPRT

0.928 0.966

0.862 0.933

0.852 0.927

0.228 0.147

61 50

CRT

ANOVA

Degrees of freedom (df)

Sum of squares (SS)

Mean square (MS)

F-value 87.784

Significance F (p-value)

Regression

4

18.341

4.585 0.052 3.423 0.021

1.89 x10 -23

Residual

56 60 45 49 4

2.925

SPRT

Total

21.266 13.692

Regression

157.792

7.3 x10 -26

Residual

0.976

CRT

Total

14.668 Table 2: Regression statistics and ANOVA for flank wear model of SPRT and CRT.

A low p-value (typically less than 0.05) indicates that the developed models are significant. Multiple R and R square values of 0.928 and 0.862, respectively, for SPRT and 0.933 and 0.927, respectively, for CRT indicate that the developed mathematical models could be used to assess the flank wear of SPRTs and CRTs during the turning of Inconel 718 within the range of the chosen process parameters. In Fig. 8, flank wear development throughout a 3-minute machining period is shown, considering the influence of cutting parameters. A single input parameter was changed, while the other two parameters were held constant to predict the flank wear results. The first section of the plot shows estimated flank wear varying with V at f and d values of 0.2 mm/rev and 0.5 mm, respectively. The middle section shows the flank wear values varying with f at a V and d of 50 m/min and 0.5 mm, respectively. The last section of the plot shows the estimated flank wear varying with d at a V and f of 50 m/min and 0.2 mm/rev, respectively. Flank wear is significantly affected by the V , followed by the t , f , and d . This can also be confirmed by the higher exponent values for the V , followed by the t , f , and d in Eqs. (2) and (3). Furthermore, with CRTs compared to SPRTs, a notable influence of the cutting conditions on flank wear is seen. The greater exponent values for the cutting parameters in Eq. (3) as opposed to Eq. (2) further support this. Further, flank wear progression was simulated for SPRTs and CRTs under cutting circumstances as shown in Tab. 3.

Figure 8: Comparative flank wear progression for SPRT and CRT varying with cutting parameters.

Experimental run

Cutting parameters

SPRT

CRT

SS1

SS2

SS3

SS4 SS5

SS6

SC1

SC2 SC3

SC4

SC5

SC6

V (m/min) f (mm/rev)

30

65

50

50

50

50

30

65

50

50

50

50

0.2 0.5

0.2 0.5

0.1 0.5

0.3 0.5

0.2 0.2

0.2 0.8

0.2 0.5

0.2 0.5

0.1 0.5

0.3 0.5

0.2 0.2

0.2

d (mm)

0.8 Table 3: Cutting conditions used for simulating flank wear progression for SPRT and CRT.

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