IMPACT OF PROCESS PARAMETERS ON DELAMINATION FORMATION OF FREEZE CLAMPED HIGH MODULUS CFRP

Given its popularity in the aerospace industry, precision machining of high-modulus thin plate Carbon Fiber Reinforced Plastics (CFRP) is paramount. To achieve high precision and low defects, selecting the right clamping methods for the CFRP plate becomes crucial to ensure the desired precision of the post-machined plate. This thesis investigates the effect of temperature, CFRP clamping strategies, tool condition, CFRP ply weaving, and machining parameters ( feed rate, cut width, fiber orientation) on the damage characteristics, surface delamination length, and forces required to edge trim CFRP thin plates. Three different clamping methods were employed: freeze clamping method, cold mechanical clamping method, and ambient temperature mechanical clamping method. To analyze the impact of clamping methods, 25.4 m slots with a 1.27 mm cut width were cut under all three clamping conditions with a feed rate of 16.932 mm/sec. Experiments were conducted on four different types of coupons differentiated based on the fiber orientation of the unidirectional bottom ply (0°, 45°, 90°, and 135°). To understand more, further experiments were conducted with the freeze clamping scenario. For the second phase of experiments, the feed rate was changed between 4.233 mm/sec, 10.5825 mm/sec, and 16.932 mm/sec. Depths of cut varied between 0.254 mm, 0.762 mm, and 1.27 mm. The required force was measured for each coupon.Delamination lengths were also measured on each coupon's woven top and unidirectional bottom surface. All the experiments were conducted inside a 3-axis CNC mini mill. The spindle speed was kept at 6000 rpm. For the experiments, a high modulus CFRP (HR 40) plate with a thickness of 1.27 mm was cut into multiple 127 mm * 22.86 mm coupons. Stat-Ease was used to design the experiments, while Lab-View software recorded the required forces. A 3-axis force sensor was used to measure the forces. It was found that the freeze clamping method reduces the deamination length the most despite requiring a higher force than the other two clamping methods. The tool's quality impacted the required force, MMR, cut depth, and feed rate. With the increasing value of MMR, cut width, and feed rate as well as worn out tool increasing the required force to cut the CFRP coupons. Increasing the value of MMR, cut width, and feed rate also increases the value of delamination. Similarly, worn-out tools reduce the surface quality by expanding the delamination length. It was also observed that weaving on the surface can minimize delamination. Fiber orientation also influences the delamination, with 90° and 45° producing some of the worst cases of delamination. Delamination was lower on 135° coupons compared to these two and the weakest on 0° coupons. All the experiments indicate that the lowest delamination fresh tool should be used at a lower MRR. Cuts should be done at 0° fiber orientation, and surfaces should be weaved. To get the best surface quality freeze clamping should be employed in case of edge trimming thin plate CFRP. The findings from the thesis are particularly important for industries that require strong materials with light weight. The aerospace and automobile industries could particularly benefit from these findings.

Numerical and experimental analysis of CFRP machining process in orthogonal cutting

Les matériaux composites, y compris le PRFC (polymère renforcé de fibre de carbone), sont de plus en plus utilisés en aéronautique et dans l'automobile, ce qui soulève actuellement de nombreuses complications dans les processus d'usinage. Comme ces matériaux sont fabriqués en plusieurs phases, ils sont responsables d'une mauvaise qualité d'usinage et de défauts indésirables. Cette thèse vise à mieux comprendre la technique physique fondamentale impliquée dans le mécanisme de formation de copeaux dans le découpage orthogonal d'usinage en PRFC par des études numériques et expérimentales combinées. Ensuite, l'analyse se concentre sur la manière dont certains paramètres de coupe, par exemple, la profondeur de coupe, affectent les efforts de coupe, la qualité de surface, les délaminations entre couches, la génération de fissures internes et la forme et la taille de copeaux générées. De plus, une observation expérimentale a été faite pour déterminer la profondeur de coupe minimale en dessous de laquelle le matériau ne peut pas être coupé en douceur sur toute la surface. Ce travail de recherche a été complété par une étude préliminaire sur le mécanisme d'usure des outils de coupe.The composite materials, including CFRP (Carbon Fiber Reinforced Polymer), are increasingly used in aeronautics and automotives which is currently raising many complications in the machining processes. As those materials are made with multiple phases, they are accountable for poor machining quality and undesired defects. This thesis seeks to better understand the fundamental physical technique involved in chip formation mechanism in orthogonal cutting of CFRP machining by combined numerical and experimental studies. Then, the analysis focuses to how certain cutting parameters, e.g., cutting depth, affect to the cutting efforts, surface quality, interply delaminations, inner crack generation and to generated chip shape and size. Moreover, an experimental observation has been made to find out the minimum cuttable depth below which the material does not get cut smoothly over the whole surface. This research work has been finished by a preliminary study on cutting tool wear mechanism

A New Cutting Device Design to Study the Orthogonal Cutting of CFRP Laminates at Different Cutting Speeds

[EN] Carbon Fiber-reinforced plastics (CFRPs) are widely used in the aerospace industry due to their highly mechanical properties and low density. Most of these materials are used in high-risk structures, where the damage caused by machining must be controlled and minimized. The optimization of these processes is still a challenge in the industry. In this work, a special cutting device, which allows for orthogonal cutting tests, with a linear displacement at a wide range of constant cutting speeds, has been developed by the authors. This paper describes the developed cutting device and its application to analyze the influence of tool geometry and cutting parameters on the material damage caused by the orthogonal cutting of a thick multidirectional CFRP laminate. The results show that a more robust geometry (higher cutting edge radius and lower rake angle) and higher feed cause an increase in the thrust force of a cutting tool, causing burrs and delamination damage. By reducing the cutting speed, the components with a higher machining force were also observed to have less surface integrity control.This research was funded by the Ministry of economy, Industry and Competitiveness and FEDER (grant number: DPI2017-89197-C2-1-R).Criado, V.; Feito-Sánchez, N.; Cantero Guisández, J.; Díaz-Álvarez, J. (2019). A New Cutting Device Design to Study the Orthogonal Cutting of CFRP Laminates at Different Cutting Speeds. Materials. 12(24):1-13. https://doi.org/10.3390/ma12244074S1131224Che, D., Saxena, I., Han, P., Guo, P., & Ehmann, K. F. (2014). Machining of Carbon Fiber Reinforced Plastics/Polymers: A Literature Review. Journal of Manufacturing Science and Engineering, 136(3). doi:10.1115/1.4026526Vigneshwaran, S., Uthayakumar, M., & Arumugaprabu, V. (2018). Review on Machinability of Fiber Reinforced Polymers: A Drilling Approach. Silicon, 10(5), 2295-2305. doi:10.1007/s12633-018-9764-9Panchagnula, K. K., & Palaniyandi, K. (2018). Drilling on fiber reinforced polymer/nanopolymer composite laminates: a review. Journal of Materials Research and Technology, 7(2), 180-189. doi:10.1016/j.jmrt.2017.06.003Wang, F., Yin, J., Ma, J., & Niu, B. (2018). Heat partition in dry orthogonal cutting of unidirectional CFRP composite laminates. Composite Structures, 197, 28-38. doi:10.1016/j.compstruct.2018.05.040Fernández-Pérez, J., Cantero, J. L., Díaz-Álvarez, J., & Miguélez, M. H. (2017). Influence of cutting parameters on tool wear and hole quality in composite aerospace components drilling. Composite Structures, 178, 157-161. doi:10.1016/j.compstruct.2017.06.043Feito, N., Díaz-Álvarez, J., López-Puente, J., & Miguelez, M. H. (2018). Experimental and numerical analysis of step drill bit performance when drilling woven CFRPs. Composite Structures, 184, 1147-1155. doi:10.1016/j.compstruct.2017.10.061López de Lacalle, L. N., & Lamikiz, A. (2009). Milling of Carbon Fiber Reinforced Plastics. Advanced Materials Research, 83-86, 49-55. doi:10.4028/www.scientific.net/amr.83-86.49Feito, N., Diaz-Álvarez, A., Cantero, J. L., Rodríguez-Millán, M., & Miguélez, H. (2015). Experimental analysis of special tool geometries when drilling woven and multidirectional CFRPs. Journal of Reinforced Plastics and Composites, 35(1), 33-55. doi:10.1177/0731684415612931Henerichs, M., Voß, R., Kuster, F., & Wegener, K. (2015). Machining of carbon fiber reinforced plastics: Influence of tool geometry and fiber orientation on the machining forces. CIRP Journal of Manufacturing Science and Technology, 9, 136-145. doi:10.1016/j.cirpj.2014.11.002Yan, X., Reiner, J., Bacca, M., Altintas, Y., & Vaziri, R. (2019). A study of energy dissipating mechanisms in orthogonal cutting of UD-CFRP composites. Composite Structures, 220, 460-472. doi:10.1016/j.compstruct.2019.03.090Lopresto, V., Langella, A., Caprino, G., Durante, M., & Santo, L. (2017). Conventional Orthogonal Cutting Machining on Unidirectional Fibre Reinforced Plastics. Procedia CIRP, 62, 9-14. doi:10.1016/j.procir.2016.07.036Santiuste, C., Olmedo, A., Soldani, X., & Miguélez, H. (2012). Delamination prediction in orthogonal machining of carbon long fiber-reinforced polymer composites. Journal of Reinforced Plastics and Composites, 31(13), 875-885. doi:10.1177/0731684412444654ZITOUNE, R., COLLOMBET, F., LACHAUD, F., PIQUET, R., & PASQUET, P. (2005). Experiment?calculation comparison of the cutting conditions representative of the long fiber composite drilling phase. Composites Science and Technology, 65(3-4), 455-466. doi:10.1016/j.compscitech.2004.09.028Rao, G. V. G., Mahajan, P., & Bhatnagar, N. (2007). Micro-mechanical modeling of machining of FRP composites – Cutting force analysis. Composites Science and Technology, 67(3-4), 579-593. doi:10.1016/j.compscitech.2006.08.010Wang, H., Chang, L., Mai, Y.-W., Ye, L., & Williams, J. G. (2018). An experimental study of orthogonal cutting mechanisms for epoxies with two different crosslink densities. International Journal of Machine Tools and Manufacture, 124, 117-125. doi:10.1016/j.ijmachtools.2017.10.003Lopresto, V., Caggiano, A., & Teti, R. (2016). High Performance Cutting of Fibre Reinforced Plastic Composite Materials. Procedia CIRP, 46, 71-82. doi:10.1016/j.procir.2016.05.079Voss, R., Seeholzer, L., Kuster, F., & Wegener, K. (2019). Analytical force model for orthogonal machining of unidirectional carbon fibre reinforced polymers (CFRP) as a function of the fibre orientation. Journal of Materials Processing Technology, 263, 440-469. doi:10.1016/j.jmatprotec.2018.08.001Seeholzer, L., Voss, R., Grossenbacher, F., Kuster, F., & Wegener, K. (2018). Fundamental analysis of the cutting edge micro-geometry in orthogonal machining of unidirectional Carbon Fibre Reinforced Plastics (CFRP). Procedia CIRP, 77, 379-382. doi:10.1016/j.procir.2018.09.040Feito, N., Diaz-Álvarez, J., López-Puente, J., & Miguelez, M. H. (2016). Numerical analysis of the influence of tool wear and special cutting geometry when drilling woven CFRPs. Composite Structures, 138, 285-294. doi:10.1016/j.compstruct.2015.11.065Cepero-Mejías, F., Curiel-Sosa, J. L., Zhang, C., & Phadnis, V. A. (2019). Effect of cutter geometry on machining induced damage in orthogonal cutting of UD polymer composites: FE study. Composite Structures, 214, 439-450. doi:10.1016/j.compstruct.2019.02.012Santiuste, C., Soldani, X., & Miguélez, M. H. (2010). Machining FEM model of long fiber composites for aeronautical components. Composite Structures, 92(3), 691-698. doi:10.1016/j.compstruct.2009.09.021Soldani, X., Santiuste, C., Muñoz-Sánchez, A., & Miguélez, M. H. (2011). Influence of tool geometry and numerical parameters when modeling orthogonal cutting of LFRP composites. Composites Part A: Applied Science and Manufacturing, 42(9), 1205-1216. doi:10.1016/j.compositesa.2011.04.023Iliescu, D., Gehin, D., Iordanoff, I., Girot, F., & Gutiérrez, M. E. (2010). A discrete element method for the simulation of CFRP cutting. Composites Science and Technology, 70(1), 73-80. doi:10.1016/j.compscitech.2009.09.007Wang, D., He, X., Xu, Z., Jiao, W., Yang, F., Jiang, L., … Wang, R. (2017). Study on Damage Evaluation and Machinability of UD-CFRP for the Orthogonal Cutting Operation Using Scanning Acoustic Microscopy and the Finite Element Method. Materials, 10(2), 204. doi:10.3390/ma10020204Sahraie Jahromi, A., & Bahr, B. (2010). An analytical method for predicting cutting forces in orthogonal machining of unidirectional composites. Composites Science and Technology, 70(16), 2290-2297. doi:10.1016/j.compscitech.2010.09.005Wang, D. H., Ramulu, M., & Arola, D. (1995). Orthogonal cutting mechanisms of graphite/epoxy composite. Part I: unidirectional laminate. International Journal of Machine Tools and Manufacture, 35(12), 1623-1638. doi:10.1016/0890-6955(95)00014-oLi, H., Qin, X., He, G., Jin, Y., Sun, D., & Price, M. (2015). Investigation of chip formation and fracture toughness in orthogonal cutting of UD-CFRP. The International Journal of Advanced Manufacturing Technology, 82(5-8), 1079-1088. doi:10.1007/s00170-015-7471-xVoss, R., Seeholzer, L., Kuster, F., & Wegener, K. (2017). Influence of fibre orientation, tool geometry and process parameters on surface quality in milling of CFRP. CIRP Journal of Manufacturing Science and Technology, 18, 75-91. doi:10.1016/j.cirpj.2016.10.002Nayak, D., Bhatnagar, N., & Mahajan, P. (2005). MACHINING STUDIES OF UNI-DIRECTIONAL GLASS FIBER REINFORCED PLASTIC (UD-GFRP) COMPOSITES PART 1: EFFECT OF GEOMETRICAL AND PROCESS PARAMETERS. Machining Science and Technology, 9(4), 481-501. doi:10.1080/10910340500398167An, Q., Cai, C., Cai, X., & Chen, M. (2019). Experimental investigation on the cutting mechanism and surface generation in orthogonal cutting of UD-CFRP laminates. Composite Structures, 230, 111441. doi:10.1016/j.compstruct.2019.111441Bhatnagar, N., Nayak, D., Singh, I., Chouhan, H., & Mahajan, P. (2004). Determination of Machining-Induced Damage Characteristics of Fiber Reinforced Plastic Composite Laminates. Materials and Manufacturing Processes, 19(6), 1009-1023. doi:10.1081/amp-200035177Wang, X., Kwon, P. Y., Sturtevant, C., Kim, D. (Dae-W., & Lantrip, J. (2013). Tool wear of coated drills in drilling CFRP. Journal of Manufacturing Processes, 15(1), 127-135. doi:10.1016/j.jmapro.2012.09.019Fernández-Pérez, J., Cantero, J. L., Álvarez, J. D., & Miguélez, M. H. (2017). Composite Fiber Reinforced Plastic one-shoot drilling: Quality inspection assessment and tool wear evaluation. Procedia Manufacturing, 13, 139-145. doi:10.1016/j.promfg.2017.09.021Sorrentino, L., Turchetta, S., Colella, L., & Bellini, C. (2016). Analysis of Thermal Damage in FRP Drilling. Procedia Engineering, 167, 206-215. doi:10.1016/j.proeng.2016.11.689Díaz-Álvarez, J., Criado, V., Miguélez, H., & Cantero, J. (2018). PCBN Performance in High Speed Finishing Turning of Inconel 718. Metals, 8(8), 582. doi:10.3390/met8080582Su, Y. (2019). Effect of the cutting speed on the cutting mechanism in machining CFRP. Composite Structures, 220, 662-676. doi:10.1016/j.compstruct.2019.04.052Wang, X. M., & Zhang, L. C. (2003). An experimental investigation into the orthogonal cutting of unidirectional fibre reinforced plastics. International Journal of Machine Tools and Manufacture, 43(10), 1015-1022. doi:10.1016/s0890-6955(03)00090-7Xu, J., El Mansori, M., Voisin, J., Chen, M., & Ren, F. (2019). On the interpretation of drilling CFRP/Ti6Al4V stacks using the orthogonal cutting method: Chip removal mode and subsurface damage formation. Journal of Manufacturing Processes, 44, 435-447. doi:10.1016/j.jmapro.2019.05.05

Microstructural investigation and hole quality evaluation in S2/FM94 glass-fibre composites under dry and cryogenic conditions

International audienceS2/FM94 glass fibre reinforced epoxy is an aerospace-grade composite currently bonded with aluminium alloys and installed in parts of the Airbus A380 fuselage. In addition to its abrasive and hard nature, S2/FM94 glass fibre is sensitive to thermal effects developed during the drilling process, and therefore using coolants becomes necessary. However, conventional oil and water-based coolants are not suitable for drilling of composites. Cryogenic coolants on the other hand are an attractive choice for machining composites and are environmentally friendly. In this study, a new environmentally friendly cryogenic cooling technique in a liquid nitrogen bath was used for the drilling of S2/FM94 glass fibre reinforced epoxy composite. The aim was to investigate the effect of drilling parameters and cryogenic cooling on cutting forces, surface roughness, hardness and delamination factor at hole entry and exit sides. The workpiece was drilled within a cryogenic bath. In this way, both cryogenic workpiece cooling and tool cooling were obtained. In addition, the drill geometry is fixed and only the cutting parameters (i.e. spindle speed and the feed rate) are varied under dry and cryogenic conditions. The results indicate that the spindle speed and cryogenic cooling had the most significant influence on the cutting forces and surface roughness parameters (R a and R z ), while the use of cryogenic cooling had the most significant influence on increasing the hardness and size of delamination at entry and exit sides of the holes

Comparison of Different Parameters to Evaluate Delamination in Edge Trimming of Basalt Fiber Reinforced Plastics (BFRP)

[EN] Delamination is one of the main problems that occur when machining fiber-reinforced composite materials. In this work, Types I and II of delamination are studied separately in edge trimming of basalt fiber reinforced plastic (BFRP). For this purpose, one-dimensional and area delamination parameters are defined. One-dimensional parameters (Wa and Wb) allow to know average fibers length while the analysis of area delamination parameters (Sd) allow to evaluate delamination density. To study delamination, different tests are carried out modifying cutting parameters (cutting speed, feed per tooth and depth of cut) and material characteristics (fiber volume fraction and fiber orientation). Laminates with a lower fiber volume fraction do not present delamination. Attending to one-dimensional parameters it can be concluded that Type II delamination is more important than Type I and that a high depth of cut generates higher values of delamination parameters. An analysis of variance (ANOVA) is performed to study area parameters. Although delamination has a random nature, for each depth of cut, more influence variables in area delamination are firstly, feed per tooth and secondly, cutting speed.This research was funded by Government of Spain, grant number PID2019-108807RB-I00.Navarro-Mas, M.; Meseguer, M.; Lluch-Cerezo, J.; García Manrique, JA. (2020). Comparison of Different Parameters to Evaluate Delamination in Edge Trimming of Basalt Fiber Reinforced Plastics (BFRP). Materials. 13(23):1-17. https://doi.org/10.3390/ma13235326S1171323Lopresto, V., Caggiano, A., & Teti, R. (2016). High Performance Cutting of Fibre Reinforced Plastic Composite Materials. Procedia CIRP, 46, 71-82. doi:10.1016/j.procir.2016.05.079Ozkan, D., Panjan, P., Gok, M. S., & Karaoglanli, A. C. (2020). Experimental Study on Tool Wear and Delamination in Milling CFRPs with TiAlN- and TiN-Coated Tools. Coatings, 10(7), 623. doi:10.3390/coatings10070623Nguyen-Dinh, N., Bouvet, C., & Zitoune, R. (2019). Influence of machining damage generated during trimming of CFRP composite on the compressive strength. Journal of Composite Materials, 54(11), 1413-1430. doi:10.1177/0021998319883335Razfar, M. R., & Zadeh, M. R. Z. (2009). Optimum damage and surface roughness prediction in end milling glass fibre-reinforced plastics, using neural network and genetic algorithm. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 223(6), 653-664. doi:10.1243/09544054jem1409Neeli, N., Jenarthanan, M. P., & Dileep Kumar, G. (2018). Multi-response optimization for machining GFRP composites using GRA and DFA. Multidiscipline Modeling in Materials and Structures, 14(3), 482-496. doi:10.1108/mmms-08-2017-0092Azmi, A. I., Lin, R. J. T., & Bhattacharyya, D. (2012). Machinability study of glass fibre-reinforced polymer composites during end milling. The International Journal of Advanced Manufacturing Technology, 64(1-4), 247-261. doi:10.1007/s00170-012-4006-6Jenarthanan, M. P., & Jeyapaul, R. (2018). Optimisation of machining parameters on milling of GFRP composites by desirability function analysis using Taguchi method. International Journal of Engineering, Science and Technology, 5(4), 22-36. doi:10.4314/ijest.v5i4.3Sreenivasulu, R. (2013). Optimization of Surface Roughness and Delamination Damage of GFRP Composite Material in End Milling Using Taguchi Design Method and Artificial Neural Network. Procedia Engineering, 64, 785-794. doi:10.1016/j.proeng.2013.09.154He, Y., Qing, H., Zhang, S., Wang, D., & Zhu, S. (2017). The cutting force and defect analysis in milling of carbon fiber-reinforced polymer (CFRP) composite. The International Journal of Advanced Manufacturing Technology, 93(5-8), 1829-1842. doi:10.1007/s00170-017-0613-6Raj, P. P., & Perumal, A. E. (2010). Taguchi Analysis of surface roughness and delamination associated with various cemented carbide K10 end mills in milling of GFRP. Journal of Engineering Science and Technology Review, 3(1), 58-64. doi:10.25103/jestr.031.11Hintze, W., Hartmann, D., & Schütte, C. (2011). Occurrence and propagation of delamination during the machining of carbon fibre reinforced plastics (CFRPs) – An experimental study. Composites Science and Technology, 71(15), 1719-1726. doi:10.1016/j.compscitech.2011.08.002Wang, F., Yin, J., Ma, J., Jia, Z., Yang, F., & Niu, B. (2017). Effects of cutting edge radius and fiber cutting angle on the cutting-induced surface damage in machining of unidirectional CFRP composite laminates. The International Journal of Advanced Manufacturing Technology, 91(9-12), 3107-3120. doi:10.1007/s00170-017-0023-9Li, M., Huang, M., Jiang, X., Kuo, C., & Yang, X. (2018). Study on burr occurrence and surface integrity during slot milling of multidirectional and plain woven CFRPs. The International Journal of Advanced Manufacturing Technology, 97(1-4), 163-173. doi:10.1007/s00170-018-1937-6Sheikh-Ahmad, J. Y., Dhuttargaon, M., & Cheraghi, H. (2017). New tool life criterion for delamination free milling of CFRP. The International Journal of Advanced Manufacturing Technology, 92(5-8), 2131-2143. doi:10.1007/s00170-017-0240-2Szwajka, K., & Trzepieciński, T. (2016). Effect of tool material on tool wear and delamination during machining of particleboard. Journal of Wood Science, 62(4), 305-315. doi:10.1007/s10086-016-1555-6Wang, F., Zhang, B., Jia, Z., Zhao, X., & Wang, Q. (2019). Structural optimization method of multitooth cutter for surface damages suppression in edge trimming of Carbon Fiber Reinforced Plastics. Journal of Manufacturing Processes, 46, 204-213. doi:10.1016/j.jmapro.2019.09.013Masek, P., Zeman, P., Kolar, P., & Holesovsky, F. (2018). Edge trimming of C/PPS plates. The International Journal of Advanced Manufacturing Technology, 101(1-4), 157-170. doi:10.1007/s00170-018-2857-1Dhand, V., Mittal, G., Rhee, K. Y., Park, S.-J., & Hui, D. (2015). A short review on basalt fiber reinforced polymer composites. Composites Part B: Engineering, 73, 166-180. doi:10.1016/j.compositesb.2014.12.011Navarro-Mas, M., García-Manrique, J., Meseguer, M., Ordeig, I., & Sánchez, A. (2018). Delamination Study in Edge Trimming of Basalt Fiber Reinforced Plastics (BFRP). Materials, 11(8), 1418. doi:10.3390/ma1108141

Current Concepts for Cutting Metal-Based and Polymer-Based Composite Materials

Due to the variety of properties of the composites produced, determining the choice of the appropriate cutting technique is demanding. Therefore, it is necessary to know the problems associated with cutting operations, i.e., mechanical cutting (blanking), plasma cutting plasma, water jet cutting, abrasive water jet cutting, laser cutting and electrical discharge machining (EDM). The criterion for choosing the right cutting technique for a specific application depends not only on the expected cutting speed and material thickness, but it is also related to the physico-mechanical properties of the material being processed. In other words, the large variety of composite properties necessitates an individual approach determining the possibility of cutting a composite material with a specific method. This paper presents the achievements gained over the last ten years in the field of non-conventional cutting of metal-based and polymer-based composite materials. The greatest attention is paid to the methods of electrical discharge machining and ultrasonic cutting. The methods of high-energy cutting and water jet cutting are also considered and discussed. Although it is well-known that plasma cutting is not widely used in cutting composites, the authors also took into account this type of cutting treatment. The volume of each chapter depends on the dissemination of a given metal-based and polymer-based composite material cutting technique. For each cutting technique, the paper presents the phenomena that have a direct impact on the quality of the resulting surface and on the formation of the most important defects encountered. Finally, the identified current knowledge gaps are discussed.publishedVersio

Experimental investigation and modeling of surface machining of high performance CFRP for the aerospace industry

Carbon fiber reinforced plastics (CFRP) have been widely used in many aircraft structures due to their light weight, high specific strength, good resistance to fatigue/corrosion and flexibility in design. Although CFRP components are produced to near-net shape, machining is often needed to remove excess materials and bring the parts to the final size and shape. However, their machining still is a big challenge due to their inherent anisotropy and inhomogeneity, which are the source of several types of damage, such as delamination, fibers pullout, and fiber-fragmentation. In order to improve machining quality and decrease the damages, a better understanding of their machining is required. Surface milling is one of the most practical processes for finishing operations but very few studies have been dedicated to its use for composite components. Thus, the purpose of this study is to use numerical and experimental methods to minimize the machining problems of CFRP materials and to gain a better understanding of CFRP surface milling process. First, the effects of different cutting conditions such as cutting speed, feed rate, and lead angle on cutting forces and surface quality were studied and the optimum cutting condition was determined. The experimental results showed that the best surface quality was achieved by using lower cutting feed rate, moderate cutting speeds, and zero degree tool lead angle. In the second part, the effects of cutting conditions and fiber orientation on cutting temperature were investigated. It was found that the cutting temperature increases linearly with the cutting speed. The maximum and minimum cutting forces and temperatures were achieved for fiber orientations of 90 and 0 degrees, respectively. Then, a finite element model was developed to predict cutting forces, chip formation mechanism and machining damages obtained during milling of unidirectional CFRP. The modeling results were validated by experimental data, including cutting forces and SEM images. A comparison of modeling and experimental results indicated that the proposed model is able to successfully predict the cutting forces and machining damages. The developed model showed that the machining damages, the chip formation, and the cutting force profile strongly depend on fiber orientation in CFRP milling process

ANALYSIS OF SURFACE INTEGRITY IN MACHINING OF CFRP UNDER DIFFERENT COOLING CONDITIONS

Carbon Fiber Reinforced Polymers (CFRP) are a class of advanced materials widely used in versatile applications including aerospace and automotive industries due to their exceptional physical and mechanical properties. Owing to the heterogenous nature of the composites, it is often a challenging task to machine them unlike metals. Drilling in particular, the most commonly used process for component assembly is critical especially in the aerospace sector which demands parts of highest quality and surface integrity. Conventionally, all composites are machined under dry conditions. While there are drawbacks related to dry drilling, for example, poor surface roughness, there is a need to develop processes which yield good quality parts. This thesis investigates the machining performance when drilling CFRP under cryogenic, MQL and hybrid (CryoMQL) modes and comparing with dry drilling in terms of the machining forces, delamination, diameter error and surface integrity assessment including surface roughness, hardness and sub-surface damage analysis. Additionally, the effect of varying the feed rate on the machining performance is examined. From the study, it is concluded that drilling using coolant/ lubricant outperforms dry drilling by producing better quality parts. Also, varying the feed rate proved to be advantageous over drilling at constant feed