The machining of fibre reinforced composites is an important activity for optimal application of these advanced materials into engineering fields. During machining any excessive cutting forces have to be avoided in order to prevent any waste product in the last stages of production cycle. Therefore, the ability to predict the cutting forces is essential to select process parameters necessary for an optimal machining. In this paper the effect of cutting conditions during milling machining on cutting force and surface roughness has been investigated. In particular the cutting force components have been analysed in function of the principal process parameters and of the contact angle. This work proposes experimental models for the determination of cutting force components for CFRP milling. 1. Introduction Composite materials milling is a rather complex task owing to its heterogeneity and some problems such as surface delamination appearing during the machining process, associated with the characteristics of the material and cutting parameters. Milling is the machining operation most frequently used in manufacturing of fibre reinforced plastics parts as a corrective operation to produce well-defined and high-quality surfaces that often require the removal of excess material to control tolerances [1]. The machinability of fibre reinforced plastics is strongly influenced by the type of fibre embedded in the composite and by its properties. Mechanical and thermal properties have an extreme importance in machining FRP. The fibre used in the composites has a great influence in the selection of cutting tools (cutting edge material and geometry) and machining parameters. It is fundamental to ensure that the tool selected is suitable for the material. The knowledge of cutting mechanisms is necessary to optimize the cutting mechanics and machinability in milling [1, 2]. Composite materials such as carbon fibre reinforced plastics (CFRPs) made by using carbon fibres for reinforcing plastic resin matrices, such as epoxy, are characterised by excellent properties as light weight, high strength, and high stiffness. These properties make them especially attractive for aerospace applications [2]. Surface roughness is a parameter that has a great influence on dimensional precision, on performance of mechanical pieces, and on production costs. For these reasons, research developments have been carried out with the purpose of optimising the cutting conditions to reach a specific surface roughness [3, 4]. The required quality of the machined surface depends on the mechanisms
References
[1]
S. Jahanmir, M. Ramulu, and P. Koshy, Machining of Ceramics and Composites, Marcel Dekker, New York, NY, USA, 2000.
[2]
W. F. Smith, Principles of Materials Science and Engineering, McGraw-Hill, New York, NY, USA, 1990.
[3]
M. Ramulu, C. W. Wern, and J. L. Garbini, “Effect of fibre direction on surface roughness measurements of machined graphite/epoxy composite,” Composites Manufacturing, vol. 4, no. 1, pp. 39–51, 1993.
[4]
E. Eriksen, “Influence from production parameters on the surface roughness of a machined short fibre reinforced thermoplastic,” International Journal of Machine Tools and Manufacture, vol. 39, no. 10, pp. 1611–1618, 1999.
[5]
P. S. Sreejith, R. Krishnamurthy, S. K. Malhotra, and K. Narayanasamy, “Evaluation of PCD tool performance during machining of carbon/phenolic ablative composites,” Journal of Materials Processing Technology, vol. 104, no. 1, pp. 53–58, 2000.
[6]
G. C. Everstine and T. G. Rogers, “A theory of machining of reinforced materials,” Journal of Composite Materials, vol. 5, pp. 94–106, 1971.
[7]
A. Koplev, A. Lystrup, and T. Vorm, “The cutting process, chips, and cutting forces in machining CFRP,” Composites, vol. 14, no. 4, pp. 371–376, 1983.
[8]
T. Kaneeda, “CFRP cutting mechanism,” in Proceedings of the 16th North American Manufacturing Research Conference, pp. 216–221, 1989.
[9]
H. Y. Puw and H. Hocheng, “Anisotropic chip formation models of cutting of FRP,” in Proceedings of the ASME Symposium on Material Removal and Surface Modification Issues in Machining Processes, New York, NY, USA, 1995.
[10]
G. Santhanakrishnan, R. Krishnamurthy, and S. K. Malhotra, “Machinability characteristics of fibre reinforced plastics composites,” Journal of Mechanical Working Technology, vol. 17, pp. 195–204, 1988.
[11]
M. Ramulu, D. Arola, and K. Colligan, “Preliminary investigation of effects on the surface integrity of fiber reinforced plastics, PD-Vol-64-2,” Engineering Systems Design and Analysis, ASME, vol. 2, pp. 93–101, 1994.
[12]
H. Hocheng, H. Y. Puw, and Y. Huang, “Preliminary study on milling of unidirectional carbon fibre-reinforced plastics,” Composites Manufacturing, vol. 4, no. 2, pp. 103–108, 1993.
[13]
W. Hintze Wolfgang, D. Hartmann, and C. Schütte, “Occurrence and propagation of delamination during the machining of carbon fibre reinforced plastics (CFRPs)—an experimental study,” Composites Science and Technology, vol. 71, no. 15, pp. 1719–1726, 2011.
[14]
D. Liu, Y. Tang, and W. L. Cong, “A review of mechanical drilling for composite laminates,” Composite Structures, vol. 94, no. 4, pp. 1265–1279, 2012.
[15]
E. U. Enemuoh, A. S. El-Gizawy, and A. C. Okafor, “An approach for development of damage-free drilling of carbon fiber reinforced thermosets,” International Journal of Machine Tools and Manufacture, vol. 41, no. 12, pp. 1795–1814, 2001.
[16]
J. P. Davim, P. Reis, and C. C. António, “Experimental study of drilling glass fiber reinforced plastics (GFRP) manufactured by hand lay-up,” Composites Science and Technology, vol. 64, no. 2, pp. 289–297, 2004.
[17]
J. Sheikh-Ahmad, J. Twomey, D. Kalla, and P. Lodhia, “Multiple regression and committee neural network force prediction models in milling FRP,” Machining Science and Technology, vol. 11, no. 3, pp. 391–412, 2007.
[18]
D. Kalla, J. Sheikh-Ahmad, and J. Twomey, “Prediction of cutting forces in helical end milling fiber reinforced polymers,” International Journal of Machine Tools and Manufacture, vol. 50, no. 10, pp. 882–891, 2010.
[19]
T. Yashiro, T. Ogawa, and H. Sasahara, “Temperature measurement of cutting tool and machined surface layer in milling of CFRP,” International Journal of Machine Tools & Manufacture, vol. 70, pp. 63–69, 2013.
[20]
J. Liu, G. Chen, C. Ji, X. Qin, H. Li, and C. Ren, “An investigation of workpiece temperature variation of helical milling for carbon fiber reinforced plastics (CFRP),” International Journal of Machine Tools and Manufacture, vol. 86, pp. 89–103, 2014.
[21]
S. Turchetta, “Cutting force on a diamond grit in stone machining,” International Journal of Advanced Manufacturing Technology, vol. 44, no. 9-10, pp. 854–861, 2009.
[22]
S. Turchetta, “Cutting force and diamond tool wear in stone machining,” International Journal of Advanced Manufacturing Technology, vol. 61, no. 5–8, pp. 441–448, 2012.
