1. Prediction of tool life for restricted contact and grooved tools based on equivalent feed J.A. Arsecularatne 24 March 2004 International Journal of Machine Tools & Manufacture 44 (2004) 1271-1282 School of Mechanical and Manufacturing Engineering, The University of New South Wales, UNSW Sydney 2052, Australia Rich Christiansen 15 October 2004

2. Function/Importance Simplify experiments required for empirical methods of tool life prediction Develop model for predicting RC and grooved tool life based on equivalent feed Tool life prediction is required for tool design, process planning, and determination of optimum cutting conditions Better tool life prediction will reduce manufacturing costs by increasing productivity

3. Cutting Tools Back wall

4. Parameters ffeed (mm/rev) F BW force component acting on back-wall in direction of cutting (N) F C force component in direction of cutting for RC/Grooved tool (N) F Cn force component in direction of cutting for natural contact tool (N) F L force component acting on rake face land in direction of cutting (N) hrake face length of restricted contact tool (mm) h n natural contact length (mm) h np plastic contact length predicted using the machining theory RCrestricted contact (tool) Ttool life (min) T f tool flank temperature for RC/grooved tool (K) T int tool-chip interface temperature for RC/grooved tool (K) T intn tool-chip interface temperature for natural contact tool (K) T SZ average temperature in the primary shear zone (C) V BB average width of flank wear land (mm)  tool rake angle (degree)  T M maximum temperature rise in chip (C)  constants

5. Design Equations Equation to predict tool life in minutes Relates interface temperatures to cutting forces Relates flank temperature to interface temperature Defines k as related to rake face length/natural contact length Estimate of interface temperature as relate to temperature in shear zone and maximum temperature rise in the chip Constant calculation Flank temperature for RC tools Estimates ratio of back-wall-force/cutting force as related to feed Rake face land force from cutting and back-wall forces

6. Experimental Equipment Experiments performed on lathe using a bar turning process under dry conditions Kistler dynamometer Nikkon microscope Cutting inserts –SNMG-120408 (chip groove on both sides) –TPMR-160304 (chip groove only on one side) Test materials –AISI-1020 plain carbon steel –AISI-1045 plain carbon steel

7. Grooved Tools

8. Experimental Procedure Cutting depth (.15-.2 mm) Feed rate (.16-.315 mm/rev) Cutting Speed (140-350 m/min) Predetermined Machining Interval Wear measurement performed after 5 machining intervals Wear measured with microscope Linear regression used to fit line to data collected Chips collected and examined

9. Results for RC Tools with Equivalent Feed RMS for 2a 26.98% RMS for 2b 27.82%

10. Results Using equivalent feed, the equation (1), the values for A and B are determined. Equation (2) shows the experimentally determined values of A and B. Both the prediction equation and the experimental results are plotted on log-log axes. (1) (2)

11. Results Predicted results from Oxley’s theory, based on the conditions, tools, and materials used in the experiment. As expected,  T M increases and h np decreases with an increase in cutting speed.

12. Results New tool life prediction methods used to create these plots. T f was first determined, and then tool life was found with equation (2). Note, at higher cutting speeds, T is not greatly affected by feed. Note also, T for high carbon steel is significantly lower than lower carbon steel. It is supposed that high carbon content shifts max temperature region towards cutting edge, thus increasing the influence of  T M on flank temperature.

13. Results Shows tool life prediction for all experimental results. The straight line is given by equation (2). It can be seen that the single line gives reasonable fit for all of the experimental data.

14. Impact Results in adequate models of tool life Relevant for high speed machining Impact on aerospace/other high speed industries Further experimental data required to further improve prediction accuracy

15. References [1]J.A. Arsecularatne, P.I.B. Oxley, Prediction of cutting forces in machining with restricted contact tools, Machining Sci Technol 1 (1)(1997)95-112 [2]J.A. Arsecularatne, P. Mathew, Prediction of tool life in machining with restricted contact tools, Int J Machining Sci Techno (Marcel Dekker) 4 (2000) 177-196 [3]J.A. Arsecularatne, Tool temperature and tool life in machining with restricted contact tools, Trans NAMRI/SME XXX (2002) 385-392 [4]J.A. Arsecularatne, On Prediction of tool life and tool deformation conditions in machining with restricted contact tools, Int J Mach Tools Manufact 43 (2003) 657-669 [5]PLB Oxley, The mechanics of machining: an analytical approach to assessing machinability, Ellis Horwood, Chichester 1989 [6]J.A. Arsecularatne, R.F. Fowle, P Mathew, PLB Oxley, Prediction of tool life in oblique machining with nose radius tools, Wear 198 (1996) 220-228 [8]H Takeyama, R. Murata, Basic investigation of tool wear, Trans ASME, J Eng Ind 85 (1963) 33-38 [9]P.K. Writght, S.P. McCormick, T.R. Miller, Effect of rake face design on cutting tool temperature distributions, Trans ASME, J Eng Ind 102 (1980) 123- 128 [10]A.V. Singh, J.A. Arsecularatne, P. Mathew, Prediction of tool life in machining with chip breaker tools, Proc. 7 th Int. Pacific Conference on Manufacturing and Management, Bangkok, Thailand, 27-29 November, 2002, vol. 1, pp. 383-389 [11]K.C. Ee, A.K. Balaji, P.X. Li, I.S. Jawahir, Force decomposition model for tool wear in turning with grooved cutting tools, Wear 249 (2002) 985-994. [12]ISO Standard 3685, Tool-life Testing with Single Point Turning Tools, 2 nd ed., 1993 [13]J. Taylor, The estimation of tool life equations by extrapolation, Proc 18 th Int. MTDR Conf., 1977, pp. 379-385 [14]J.A. Arsecularatne. O.S Jawahir, Prediction and validation of cutting forces in machining of plain carbon steels with chip breaker tools, Trans NAMRI/SME XXIX (2001) 367-374