Eckart Uhlmann, and Je Evaluation of carbon ﬁber

Research Article

Ever Grisol de Melo*, Jéssica Christina dos Santos Silva, Tiago Borsoi Klein, Julian Polte,Eckart Uhlmann, and Jefferson de Oliveira Gomes

Evaluation of carbon fiber reinforcedpolymer – CFRP –machining by applyingindustrial robots

https://doi.org/10.1515/secm-2021-0026received November 09, 2020; accepted January 21, 2021

Abstract: Carbon fiber reinforced polymer (CFRP) is widelyused in high-tech industries because of its interestingcharacteristics and properties. This material presentsgood strength and stiffness, relatively low density, highdamping ability, good dimensional stability, and goodcorrosion resistance. However, the machinability of com-posite materials is complex because of the matrix/fiberinterface, being a challenging machining material. TheCFRPmilling process is still necessary tomeet dimensionaltolerances, the manufacture of difficult-to-mold featureslike pockets or complexes advance surfaces, finish theedges of laminated composites, or drill holes for theassembly of the components. Besides, the demand forlow-cost, reconfigurable manufacturing systems of theindustry demonstrates that the application of industrialrobots (IRs) in the CFRP milling process becomes an alter-native for providing automation and flexibility. Therefore,the objective of this work is to evaluate the performance ofthe low payload IR KUKA KR60 HA in a milling experimentof CFRP, which indicates its potential application as analternative to milling process. Furthermore, the influenceof the cutting tool geometry as well as the cutting para-meters in the machining behavior with IRs is evaluated.

Keywords: carbon fiber reinforced polymer, industrialrobot, machining process, milling, cutting tools

1 Introduction

Carbon fiber reinforced polymer (CFRP) is widely used inhigh-performance applications, where high strength-to-weight ratio (specific strength) and stiffness constituteimportant requirements. CFRP has two main compo-nents: (i) high-strength carbon fibers and (ii) the flexibleand tough matrix material [1]. This provides interestingcharacteristics and properties such as specific strengthand stiffness, relatively low density, high damping ability,good dimensional stability, and good corrosion resistance.These qualifications call attention to large industrial areassuch as automotive, aerospace, marine industries, andcivil engineering, wind-turbines, sport equipment, androbotics [2,3]. Therefore, it possesses a high potential forthe substitution of, for example, heavier aluminum andsteel [4,5]. However, after the production of CFRP’s shape,the machining of these materials is still necessary to meetdimensional tolerances, the manufacture difficult-to-moldfeatures like pockets or surfaces, finish the edges of lami-nated composites, or drill holes for reasons of assembly.Further, the cutting mechanism of CFRP greatly varies com-pared to conventional metallic material cutting mechanism,so that it becomes difficult in analyzing their machiningperformance [6–8]. The main challenges in machiningof CFRPs arise from the anisotropy and inhomogeneity ofthe composite, which generates spalling, delamination,fuzzing, fiber pull-outs, matrix cracking, and thermal degra-dation [9,10]. The damages caused in the machining pro-cess of the CFRP may harm the surface and dimensionalquality and can, therefore, cause the rejection of the work-piece [11–13]. Despite the research published over the pastdecades on the process of machining CFRP, this theme isstill in the early stages of development.

* Corresponding author: Ever Grisol de Melo, Department ofMechanical Engineering, Aeronautics Institute of Technology (ITA),Marechal Eduardo Gomes 50, São José dos Campos, 12228-900,Brazil; Production System, Fraunhofer Institute for ProductionSystems and Design Technology (IPK), Pascalstraße 8-9, Berlin,10587, Germany, e-mail: [email protected], [email protected]éssica Christina dos Santos Silva, Jefferson de Oliveira Gomes:Department of Mechanical Engineering, Aeronautics Institute ofTechnology (ITA), Marechal Eduardo Gomes 50, São José dosCampos, 12228-900, BrazilTiago Borsoi Klein, Julian Polte, Eckart Uhlmann: ProductionSystem, Fraunhofer Institute for Production Systems and DesignTechnology (IPK), Pascalstraße 8-9, Berlin, 10587, Germany

Science and Engineering of Composite Materials 2021; 28: 285–298

Open Access. © 2021 Ever Grisol de Melo et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0International License.

https://doi.org/10.1515/secm-2021-0026

mailto:[email protected]

mailto:[email protected]

Because it is in early development, there are gaps onthe topics of surface finish, reduced form tolerance andincreased tool life, as well as increased automation andflexibility of the machining processes. The demand forlow-cost, reconfigurable manufacturing systems of theindustry demonstrates that the application of industrialrobots (IRs) in the CFRP milling process becomes an alter-native for providing automation and flexibility [12,14]. Inthe last 9 years, research focused on CFRP machiningapplying IRs has become of great academic and industrialinterest (see Figure 1). According to Schneider et al., moreand more IRs have been unidirectional and wove material,used for a machining operation, because of offering lowercosts than conventional machine tools, an exceptionalflexibility and a big working area [15]. In addition, thepurchase cost of an IR is 30–50% lower when comparedto machine tools [16].

Only 2.0% of IRs is used for processes such as cut-ting, milling, or grinding [17]. Machining processes thatapply IR are currently used for the machining of compo-nents characterized by low cutting forces (polishing,deburring, and deflashing) or low accuracy. To ensurethe dimensional and surface quality, a combination offactors is required, from the cutting tool to the roboticconfiguration. It is therefore essential to understand thedynamics of the IR. Krzic et al. [18], Mejri et al. [19], Gonulet al. [14], and Bisu et al. [20] analyzed the dynamic andstability performance of the IR in the machining process.Slamani et al. [21,22] analyzed the application of an IR,with a load capacity of P < 500 kg, for CFRP machining.Zaghbani et al. [23,24] proposed a method based on the

variation in spindle speed, which was introduced formachining operation and a new process stability criterion(CS) based on acceleration energy distribution and forcesignal was proposed for the analysis of an ABB IRB1600 IR.

According to Chen et al. [25], there is still a long wayto go before robot machining systems are widely used inpractical applications, and the use of existing IRs hashindered the development of robot machining in recentyears. The development of new robotic structures willtake a few more years and it has also not been confirmedwhether the cost of the investment will be economicallyviable. The development of this technology is a requisiteto meet the demands of the current industry [26–28].Therefore, this work contributes to the scientific under-standing in evaluating the performance of the low pay-load IR (KUKA KR60 HA) for a milling of CFRP, whichindicates its potential application as an alternative toconventional milling processes performed with machinetools. Furthermore, the influence of the cutting tool geo-metry as well as the cutting parameters in the machiningbehavior with IRs is evaluated.

2 Materials and methods

The study explored the functionality of the IR, the geo-metry of the cutting tools, and the cutting parametersthat influence in CFRP machining conditions, in whichfiber pull-outs, delamination, surface roughness Ra, andcutting force F were evaluated. Figure 2 shows the details

Figure 1: Number of researches in machining, robot, and CFRP.

286 Ever Grisol de Melo et al.

of the unidirectional and woven fibers that were usedfor the slotting milling tests. The used workpiece materialin both plates, unidirectional and wove, is a meshworkof carbon fibers in an epoxy resin. The carbon fibersof unidirectional material have a diameter of 7 μm, analignment of 0°, and a proportion of ∼65%, with 11 innerlayers in 4mm thick (Figure 2a). The carbon fibers ofwove material have a proportion of ∼33%, a diameterof 13 μm, and are woven with an alignment of 0°/90°,an epoxy matrix reinforced with 55% of carbon fiber(Figure 2b). Both materials are in the phase of industrialdevelopment.

Some researchers have reported about the conse-quence of process parameters, such as high spindlespeed/cutting speed and feed rate on the quality of themachined surface. Previous research showed that HSCapplication provides a better surface finish in terms offiber pull-out. However, it is important to remark thathigh values of the cutting speed can cause delamination[12,29–33]. This motivated further investigations into theinfluence of these cutting parameters on the milling ofdifferent CFRPmaterials. Table 1 shows all the factors andlevels of the experimental designs used for unidirectionalmaterial milling. In the case to milling of the woven com-posite applied the cutting speed vc = 602m/min and vc =904m/min with feed rate vf = 2 m/min were applied, forall cutting tools. The use of a only one feed rate vf for the

two cutting speed vc has been done to understand theinfluence of the vc on CFRP milling.

The slotting milling tests were carried out on a 6-axisIR, from the company KUKA AG, Augsburg, Germany,KR60 HA that manipulated a spindle ES350L 4P of 8 kWnominal power –HSD SPA delivering spindle speeds ofn = 36,000 rpm, from the company HSD SPA, Gradara,Italy. A suction system was used to remove dust with anextraction nozzle placed locally in the spindle (Figure 3a).Three sets of tests were produced. The cutting tool F0 hasa geometry with four cutting teeth and four secondaryteeth, and 6° right flute. The cutting tool F1 has the geo-metry with nine teeth in right helix, with right cutting andoptimized chip breaker division, and the cutting tool F2has a geometry with two teeth end mill style, narrow-toothed with pyramidal edge, with grinding functionalityto the matrix of the composite (Figure 3b). All tested cut-ting tools are from the company Hufschmied Zerspan-nungssysteme GmbH, Germany. The company generallysuggests the use of diamond coated tools for CFRPmachining. However, in this work it was chosen to usetools without coating to verify more quickly the influenceof the geometry on the work result. All used tools aremade of uncoated carbide with a cobalt content wCo =6M%, a hardness 1,620 HV 30, and an average grainsize dWC = 1.3 μm. Cutting force F signals during themilling process were monitored by an SI-660-60 sensorfrom the company ATI Industrial Automation, Apex, USA(see Figure 3c). This sensor is installed between the IRflange (6 – axis) and the spindle.

According to Gao et al. [34], the surface roughness Rahas a predominant role in determining the machiningaccuracy. The surface roughness Ra of CFRP machineddepends on many factors, such as fiber orientation, cuttingspeed, feed rate, and depth of cut, for a given machine tooland workpiece setup. Thus, it is necessary to measurethe roughness of the machined surface to evaluate boththe machining process and the type of fiber orienta-tion. The machined surface roughness Ra parameter usedthroughout this work is defined by ISO 4287:1997 [35].The SJ-201P Portable Surface Roughness Tester, from

Figure 2: Illustration of the types of CFRP layups: (a) unidirectional,all fiber area aligned uniformly; (b) woven, fibers within each layerare interlocked.

Table 1: Experimental design of experiment

Factor Level

1 2 3

vc (mmin) 301 602 904vf (mmin) 1 2 4Tool F0 F1 F2

Evaluation of CFRP machining by applying IRs 287

the company MITUTOYO, Tokyo, Japan, was used forroughness measurements according to ISO 4287:1997recommendation (see Figure 4a). The roughness wasmeasured at three different positions on each sample.The average values were taken, evaluating the surfaceroughness Ra of the down milling and up milling, indi-vidually. The arithmetic average surface roughness Raused in this work can be described in mathematical func-tion as equation (1):

∑= ∣ ∣N

HRa 1 ,i

N

i (1)

where Hi is the height of roughness irregularities fromprofile and N is the number of measured points insample length. Ra value can be calculated from themean height [35].

The changing industrial scenario related to Industry4.0 is motivating researchers to develop more flexible,efficient, and smart processes. Machining CFRP by applyingIRs is an alternative to what is currently used in the industry.However, on account of the need for increasingly high feedrates and low rigidity of IRs, it is fundamental to ensure thedimensional quality of the machined workpiece. Therefore,to measure the dimensional quality of machining tests byapplying an IR, a coordinate measuring machine Crysta-Apex C 7000 MPEE, from the company MITUTOYO, Tokyo,Japan, was used (see Figure 4b). The evaluation of the pull-outs and delamination was measured from the photos taken

by Dino-Lite digital microscope, from the company DINO-LITE, New Taipei City, Taiwan. All the combinations of cut-ting parameters in milling experiments were evaluated.

3 Results and discussion

According to Kalla et al. [36], the machining quality ofCFRP is described by the surface finish and surface integ-rity. The measurement results of average surface rough-ness Ra are shown in Figures 5 and 6. According toChoudhury and Hashmi [37], the surface roughness Raon the workpiece tends to decrease as the cutting speedincreases. Considering the evaluated cutting tools in thewove material milling process, the cutting tool F1 showedan increase in surface roughness Ra as the cutting speedincreases in wove material (Figure 5). The geometry pro-file of the cutting tool F1 shows chip breakage divisions,and because the size of the chip breakage slots and thepositioning of these slots are aligned, this generates non-uniform cutting regions. Even so, the geometry of thecutting tool F1 obtained the lower surface roughnessresults for the wove material. The cutting tool F0 has ofgeometry with four cutting teeth and four secondaryteeth, both of serrated teeth. The cutting tool F0 obtainedthe highest surface roughness Ra values, between Ra =6.52 µm and Ra = 5.32 µm. The serrated teeth profile

Figure 3: Experimental setup: (a) IR setup; (b) cutting tools, and (c) cutting force sensor.


provided the highest surface roughness Ra values. How-ever, the increased cutting speed vc resulted in a decreasein surface roughness Ra. This was because of a lower feedper tooth fz, causing less roughness spacing on the

surface of the material. The same roughness profile char-acteristic is found for cutting tool F2. The narrow-toothedwith pyramidal edge provides cuts in the material planeby intercalated teeth (see Figure 5).

Figure 4: Setup for evaluation of surface roughness Ra and dimensional quality: (a)Mitutoyo SJ-201P portable surface roughness tester and(b) Crysta-Apex C 7000 MPEE.

Figure 5: Roughness surface (Ra) results of wove material.


Regarding the surface roughness Ra of the unidirec-tional material, the cutting tools F0 and F1 also showeddifferent behavior suggested by Choudhury and Hashmi[37]. In Figure 6, the cutting tools F0 and F1 in the downmilling process showed a decrease in the surface rough-ness Ra when the feed rate vf is increased, at the samecutting speed vc. Besides, the cutting tool F0 when ana-lyzing the increased cutting speed vc and constant feedrate vf provides an increase in surface roughness. Thecutting tool F1 maintained the surface roughness Ra con-stant for increased cutting speed vc (Figure 6). The cuttingtool F2 showed a uniform surface roughness Ra profile inall experiments, unidirectional, and wove material. Thiscan be explained by its narrow-toothed cutting geometrywith pyramidal edge (see Figures 5 and 6). Another factorto note is the downmilling results in lower surface rough-ness Ra than up milling, regardless of the cutting tool used.Diverging what was proposed by Sheikh-Ahmad et al. [38]

and Gara and Tsoumarev [39], that damage occurred alwayson the down-milling process. The cutting tool F0 had thepoorer performance of surface roughness Ra = 7.83 µm tospeed cutting vc = 904m/min and feed rate vf = 1m/min(Figure 6). This states that the machinability of compositematerials, for example, CFRP, should be analyzed on a case-by-case basis. According to Azmi and Lin [40], the higherfeed rate vf leads to an increase in strain rate on the com-posite, which generates fracture of the fiber resulting inpoor surface roughness. The factors tested (cutting tool geo-metries, cutting parameters and up and down milling)showed no significant influence on the milled surfaceroughness. This is because of anisotropy and the inhomo-geneity of the composite, and occasionally the surfaceroughness Ra results are non-standard.

Milling quality analysis includes dimensional, surface,pull-outs, and delamination deviation. According toJayaweera and Webb [41], the aero-structure components

Figure 6: Roughness surface results of unidirectional material: (a) cutting tool F0, (b) cutting tool F1, and (c) cutting tool F2.


could be assembled within tol = 0.6 mm tolerance. Toachieve the desired quality of the machined surface, itis necessary to understand the cutting mechanisms ofmaterial removal and the kinetics of machining processesinfluencing the performance of the cutting tools [42].According to Bolar et al. [43], the surface quality is animportant requirement for components used in the aero-space and automobile industries. The quality of the CFRPpart machined is assessed according to the delamina-tion and fiber protrusion, and this is particularly crucialto avoid rejection of parts. Currently, there is no standar-dized method for the CFRP quality control, whichmakes the analyses strongly conditioned to each end-user [12]. Figures 7 and 8 show qualitative results of themachined surface of unidirectional material and wovematerial, respectively. The cutting tool F0 in down

milling operation showed less damage to the surfacewhen compared to up milling operation (Figure 7). Never-theless, in the experiment with wove material the cuttingtool F0 presented better finishing surface for up millingoperation (Figure 8). In general, the geometry of the cut-ting tool F1 showed the best qualitative results, cuttingcondition vc = 904m/min and vf = 4m/min, for bothmaterials (Figures 7 and 8). The cutting tool F2 showedhigher surface damage, crack, to the cutting condition ofthe high feed rate, vf = 4m/min. However, in the wovematerial experiment the up milling operation presentedbetter conditions of the machined surface and showed nosurface damage to any of the cutting tool geometries(Figure 8). This demonstrates the importance of an excel-lent correlation between material, cutting parameters,and cutting tool geometry to achieve satisfactory surface

Figure 7: Comparison of surface quality criteria of unidirectional material – cutting parameters and cutting tool geometries.


qualities. The wovematerial presents higher surface damage,crack of the laminates. This demonstrated the influence ofcutting parameters in quality of the material machining.Further research is required to make this type of correla-tion possible. Delamination occurred only for F2 withextreme cutting condition.

Another way to evaluate the pull-out compliance wasconsidered quantitative measure. Figure 9 shows thepull-out values in down and up milling for unidirectionalmaterial. The cutting tool F0 did not have a pull-out indown milling for high feed rate vf = 4m/min and cuttingspeeds of vc = 301 m/min and vc = 904m/min (Figure 9a).The cutting tool F1 did not have a pull-out in downmilling for low cutting speeds (Figure 9b). The cuttingtool F2 did not have a pull-out in down milling only atvc = 904m/min and vf = 4m/min (Figure 9c). Pull-out

occurred for all combinations of up milling cutting para-meters. In wove material experiments, only the cuttingtool F0 did not have a pull-out in the down milling(Figure 10). The cutting tool F1 had the highest pull-outvalues for both materials. These qualitative results corro-borate that the current state of the literature cannot yetdirectly correlate the pull-out with cutting parameter orcutting tool geometry.

Roesch [44] has machining experiments with a robotof type KR 240 R2500. In Roesch’s experiments, anachievable absolute positional error of E = 0.14 mm wasevidenced and showed a reduction in process-relatedtool path deviations. To validate the performance of thelow payload IR KR 60 HA in CFRP milling, the dimen-sional deviation was measured. The dimensional devia-tion was calculated by the difference between the

Figure 8: Comparison of surface quality criteria of wove material – cutting parameters and cutting tool geometries.


Figure 9: Pull-out results of unidirectional material (a) F0, (b) F1, (c) F2.

Figure 10: Pull-out results of wove material.


standard geometry and the final geometry after roboticmachining. The dimensional quality for CFRP machiningby the application of low load IR was influenced by allstudy factors: cutting tool geometry, composite materialtype, and cutting parameters. The cutting tools F0 and F2showed dimensional errors below D = 0.14mm in theexperiments for the unidirectional material, and the cut-ting tool F1 has the largest dimensional deviations (seeFigure 11a). These results are directly the oscillation ofthe cutting force, as shown in Figure 12. It is important tonote that the increased cutting speed for all experimentshas negatively influenced the tool path. Moreover, onlythe combination of cutting tool F0 and vc = 602m/minobtained a dimensional deviation of less than D = 0.14mmfor wove material milling. The woven composite presentedhigher values for dimensional deviation (see Figure 11b),which can be explained by the fact that it contains in itsreinforced epoxy matrix a proportion of 55% of carbonfiber with a fiber orientation of 0/90°. The cutting processfor this type of material generated greater instabilities,which influenced the tool path.

According to Kienzle [45], the force cutting F is mainlyinfluenced by the feed rate. However, because of non-homogeneity and anisotropy of composite materials, other

variables have a significant influence on the machining ofthese materials, such as the geometry of the cutting tooland the cutting speed. The cutting forces F show differentpatterns in different fiber orientations, unlike in metal cut-ting [11]. Figure 12 shows the cutting force of the threecutting tools and the cutting parameter combinations.The low pass filter was applied to generate the cuttingforce profile (black line in Figure 12). The cutting forceprofiles presented for the tests had a high initial forcebecause of the cutting tool plunge strategy in the work-piece and during milling a harmonic behavior. The highcutting speeds can help smooth resultant force [12] evenby increasing the feed rate by four times (see Figure 12).Regarding the cutting force, it can be observed that theincrease in cutting speed vc has made it possible to gainthe feed rate vf, in addition to maintaining or even redu-cing the cutting force. The cutting tool F0 showed a lowoscillation of cutting force during the experiments for thecombination of cutting parameters vc = 904m/min and vf =4m/min (see Figure 12a), demonstrating excellent perfor-mance for extreme cutting parameters. On the contrary,the F1 cutting tool presented this type of performance forlower cutting parameters, vc = 301m/min, and vf = 1m/min(see Figure 12b). Besides, the cutting tool F1 has a high

Figure 11: Dimensional deviation results: (a) unidirectional material and (b) wove material.


oscillation of the cutting force for the maximum cuttingcondition. This high oscillation generated a greater dimen-sional deviation, as presented previously. This is becauseof less instability generated in the tool path as the feed rateincreases. This reiterates the influence not only of the feedrate vf, but also of the geometry of the cutting tool and thetype of composite material. Both cutting tools have asimilar geometry but different cutting force results. The

cutting tool F2 showed high oscillation of cutting forcefor all experiments. Even so, it obtained the lowest cuttingforce values in unidirectional material milling. These resultsare because of the geometry of the cutting tool F2 which hasnarrow teeth with pyramidal edge, in which it helps to grindthe composite matrix. In the wove material milling test, thefeed rate was set constant vf = 2m/min. As already men-tioned, composite material has diverse structures that will

Figure 12: Cutting force profile for material unidirectional material: (a) cutting force F0, (b) cutting force F1, and (c) cutting force F2.


directly affect its machinability. The performance of thecutting tools in the milling of wove material demonstratesthis influence. According to Ahmad [46], the cutting forcefor multidirectional laminates was always greater than uni-directional laminates. In addition, the rate of decrease in thecutting force depends also on fiber orientation. Divergingfrom what is proposed by Ahmad [46], the values of thecutting forces for the wove material were lower than thosecompared to the unidirectional material. It should be notedthat only the F2 cutting tool has made significant gains byincreasing the cutting speed. This is also explained by thegeometry of its narrow teeth with pyramidal, which is ableto grind the matrix. However, the cutting tool F1 showed anincrease in the cutting force F with the increased cuttingspeed vc (see Figure 13b).

4 Conclusion

The present work is focused on the analysis of CFRPmilling by the application of the low payload IRs fortwo materials: unidirectional and wove. The experiments

carried out involved the evaluation of cutting force,roughness surface, pull-out, delamination, and dimen-sional quality, considering the phenomena of the cuttingtools and cutting parameters.• The surface roughness Ra for both materials was lessthan 8 µm in all tests. The down milling results in lowersurface roughness Ra than up milling, regardless of thecutting tool used for unidirectional composite milling,demonstrating the preference for down milling whenapplying IR in CFRP milling.

• The surface roughness Ra of wove material also showednon-standard results. All cutting tools showed similarresults between down and up milling.

• The unidirectional milling, the cutting tool F0 did notshow any significant pull-out in down milling. Pull-outoccurred for all combinations of up milling cuttingparameters.

• In the wove milling, only the cutting tool F0 did nothave a pull-out in the down milling. The cutting tool F1had the highest pull-out values for both materials.However, it was not possible to correlate this data ina uniform or standardized way neither for the cuttingparameters nor for the cutting tools.

Figure 13: Result of cutting forces: (a) unidirectional material and (b) wove material.


• In general, no delamination occurs during CFRP milling.Delamination occurred only for F2 with extreme cuttingcondition.

• The cutting tool F1 has the largest dimensional devia-tions, Dmax = 0.23 mm in robotic milling. On the con-trary, only the combination of cutting tool F0 with vc =602 m/min obtained a dimensional deviation of lessthan D = 0.14 mm for wove material milling.

• The increased cutting speed for all experiments hasnegatively influenced the tool path.

• The cutting tool F0 showed a low oscillation of cuttingforce during the experiments and excellent perfor-mance for extreme cutting parameters. On the contrary,the F1 cutting tool presented good performance forlower cutting parameters and high oscillation of thecutting force for the maximum cutting condition.

• The material has diverse structures (fiber and matrix)that will directly affect its machinability. The perfor-mance of the cutting tools in the milling of wove mate-rial demonstrates this influence. In these experiments,the values of the cutting forces for the wove materialwere lower than those compared to the unidirectionalmaterial, diverging from another research.

• The proposed cutting parameters for robotic machining,as well as the cutting tool geometry, have shown thatthere is no pattern of the results for pull-out, delamina-tion, dimensional quality and cutting force. Reaffirmingthe need for more studies on the machinability of compo-site materials. But also demonstrating the technical feasi-bility of applying IRs in composite milling processes.

Acknowledgments: This work was supported by theCoordination for the Improvement of Higher EducationPersonnel – CAPES (grant number 88882.180844/2018-01); German Academic Exchange Service –DAAD (grantnumber 91744162); Institute for Production Systems andDesign Technology – IPK; and Aeronautics Institute ofTechnology – ITA.

Conflict of interest: Authors state no conflict of interest.

References

[1] Geier N, Davim JP, Szalay T. Advanced cutting tools and tech-nologies for drilling carbon fibre reinforced polymer (CFRP)composites: a review. Compos Part A Appl Sci Manuf.2019;125:105552. doi: 10.1016/j.compositesa.2019.105552.

[2] Lopresto V, Caggiano A, Teti R. High performance cutting offibre reinforced plastic composite materials. Procedia CIRP.2016;46:71–82. doi: 10.1016/j.procir.2016.05.079.

[3] Davim JP, editor. Machining composite materials. London:ISTE; 2010.

[4] Heinrich JG, Aldinger F. Ceramic materials and components forengines. Wiley; 2008. ISBN:3-527-30416-9 - Book.

[5] Rosato DV, Rosato MG, Schott NR. Plastics technology hand-book, volume 1: Introduction, properties, fabrication, pro-cesses. 1st edn. New York, NY (222 East 46th Street, New York,NY 10017): Momentum Press; 2010.

[6] Panchagnula KK, Palaniyandi K. Drilling on fiber reinforcedpolymer/nanopolymer composite laminates: a review. J MaterRes Technol. 2018;7(2):180–9. doi: 10.1016/j.jmrt.2017.06.003.

[7] Abrão AM, Faria PE, Rubio JC, Reis P, Davim JP. Drilling of fiberreinforced plastics: a review. J Mater Process Technol.2007;186(1–3):1–7. doi: 10.1016/j.jmatprotec.2006.11.146.

[8] Vigneshwaran S, Uthayakumar M, Arumugaprabu V. Review onmachinability of fiber reinforced polymers: a drilling approach.Silicon. 2018;10(5):2295–305. doi: 10.1007/s12633-018-9764-9.

[9] Hejjaji A, Zitoune R, Crouzeix L, Le Roux S, Collombet F.Surface and machining induced damage characterization ofabrasive water jet milled carbon/epoxy composite specimensand their impact on tensile behavior. Wear.2017;376–377:1356–64. doi: 10.1016/j.wear.2017.02.024.

[10] Haddad M, Zitoune R, Eyma F, Castanie B. Study of the surfacedefects and dust generated during trimming of CFRP: Influenceof tool geometry, machining parameters and cutting speedrange. Compos Part A Appl Sci Manuf. 2014;66:142–54.doi: 10.1016/j.compositesa.2014.07.005.

[11] He Y, Qing H, Zhang S, Wang D, Zhu S. The cutting force anddefect analysis in milling of carbon fiber-reinforced polymer(CFRP) composite. Int J Adv Manuf Technol.2017;93(5–8):1829–42. doi: 10.1007/s00170-017-0613-6.

[12] Grisol de Melo E, Klein TB, Reinkober S, Gomes JDO,Uhlmann E. Pocket milling of composite fibre-reinforcedpolymer using industrial robot. Procedia CIRP. 2019;85:183–8.doi: 10.1016/j.procir.2019.09.006.

[13] Uhlmann E, Sammler F, Richarz S, Reucher G, Hufschmied R,Frank A, et al. Machining of carbon and glass fibre reinforcedcomposites. Procedia CIRP. 2016;46:63–6. doi: 10.1016/j.procir.2016.03.197.

[14] Gonul B, Sapmaz OF, Tunc LT. Improved stable conditions inrobotic milling by kinematic redundancy. Procedia CIRP.2019;82:485–90. doi: 10.1016/j.procir.2019.04.334.

[15] Schneider U, Ansaloni M, Drust M, Leali F, Verl A. Experimentalinvestigation of sources of error in robot machining. In: Neto P,Moreira AP, editors. Robotics in smart manufacturing. BerlinHeidelberg: Springer; 2013. p. 14–26.

[16] Iglesias I, Sebastián MA, Ares JE. Overview of the state ofrobotic machining: current situation and future potential.Procedia Eng. 2015;132:911–7. doi: 10.1016/j.proeng.2015.12.577.

[17] Schneider U, Drust M, Ansaloni M, Lehmann C, Pellicciari M,Leali F, et al. Improving robotic machining accuracy throughexperimental error investigation and modular compensation.Int J Adv Manuf Technol. 2016;85(1–4):3–15. doi: 10.1007/s00170-014-6021-2.

[18] Krzic P, Pušavec F, Kopac J. Kinematic constraints and offlineprogramming in robotic machining applications. TehničkiVjesn. 2013;20(1):117–24.


[19] Mejri S, Gagnol V, Le T-P, Sabourin L, Ray P, Paultre P. Dynamiccharacterization of machining robot and stability analysis.Int J Adv Manuf Technol. 2016;82(1–4):351–9. doi: 10.1007/s00170-015-7336-3.

[20] Bisu C, Cherif M, Gerard A, K’nevez JY. Dynamic behavior ana-lysis for a six axis industrial machining robot. Adv Mater Res.2011;423:65–76. doi: 10.4028/www.scientific.net/AMR.423.65.

[21] Slamani M, Joubair A, Bonev IA. A comparative evaluation ofthree industrial robots using three reference measuring tech-niques. Ind Robot. 2015;42(6):572–85. doi: 10.1108/IR-05-2015-0088.

[22] Slamani M, Nubiola A, Bonev I. Assessment of the positioningperformance of an industrial robot. Ind Robot.2012;39(1):57–68. doi: 10.1108/01439911211192501.

[23] Zaghbani I, Songmene V, Bonev I. An experimental study onthe vibration response of a robotic machining system. ProcInst Mech Eng Part B J Eng Manuf. 2013;227(6):866–80.doi: 10.1177/0954405413477067.

[24] Zaghbani I, Lamraoui M, Songmene V, Thomas M, ElBadaoui M. Robotic high speed machining of aluminum alloys.Adv Mater Res. 2011;188:584–9. doi: 10.4028/www.scienti-fic.net/AMR.188.584.

[25] Chen Y, Dong F. Robot machining: recent development andfuture research issues. Int J Adv Manuf Technol.2013;66(9–12):1489–97. doi: 10.1007/s00170-012-4433-4.

[26] Denkena B, Lepper T. Enabling an industrial robot for metalcutting operations. Procedia CIRP. 2015;35:79–84.doi: 10.1016/j.procir.2015.08.100.

[27] Denkena B, Bergmann B, Lepper T. Design and optimization ofa machining robot. Procedia Manuf. 2017;14:89–96.doi: 10.1016/j.promfg.2017.11.010.

[28] Möller C, Schmidt HC, Koch P, Böhlmann C, Kothe SM, Wollnack J,et al. Machining of large scaled CFRP-Parts with mobile CNC-based robotic system in aerospace industry. Procedia Manuf.2017;14:17–29. doi: 10.1016/j.promfg.2017.11.003.

[29] Uhlmann E, Meier P, Hinzmann D. Application of niobium car-bide based cutting materials for peripheral milling of CFRP.Procedia CIRP. 2019;85:108–13. doi: 10.1016/j.procir.2019.09.009.

[30] M’Saoubi R, Axinte D, Soo SL, Nobel C, Attia H, Kappmeyer G,et al. High performance cutting of advanced aerospace alloysand composite materials. CIRP Ann. 2015;64(2):557–80.doi: 10.1016/j.cirp.2015.05.002.

[31] Ulhmann E. Machining of carbon and glass fibre reinforcedcomposites. 7th HPC 2016 – CIRP Conference on HighPerformance Cutting; 2016. p. 63–6. doi: 10.1016/j.procir.2016.03.197.

[32] Ulhmann E. High speed cutting of carbon fibre reinforcedplastics. 16th Machining Innovations Conference forAerospace Industry – MIC 2016/6(6); 2016. p. 113–23.doi: 10.1016/j.promfg.2016.11.015.

[33] Uhlmann E, Richarz S, Sammler F, Hufschmied R. High speedcutting of carbon fibre reinforced plastics. Procedia Manuf.2016;6:113–23. doi: 10.1016/j.promfg.2016.11.015.

[34] Gao C, Xiao J, Xu J, Ke Y. Factor analysis of machining para-meters of fiber-reinforced polymer composites based on finiteelement simulation with experimental investigation. Int J AdvManuf Technol. 2016;83(5–8):1113–25. doi: 10.1007/s00170-015-7592-2.

[35] The International Organization for Standardization.Geometrical product specifications (GPS) – Surface texture:profile method – terms, definitions and surface texture para-meters. Available from: https://www.iso.org/standard/10132.html [cited 2020 February 3].

[36] Kalla D, Sheikh-Ahmad J, Twomey J. Prediction of cutting forcesin helical end milling fiber reinforced polymers. Int J MachTools Manuf. 2010;50(10):882–91. doi: 10.1016/j.ijmachtools.2010.06.005.

[37] Choudhury IA, Hashmi S. Finish machining and net-shapeforming. Waltham MA: Elsevier; 2017.

[38] Sheikh-Ahmad J, El-Hofy M, Almaskari F, Kerrigan K,Takikawa Y. The evolution of cutting forces during slot millingof unidirectional carbon fiber reinforced polymer (UD-CFRP)composites. Procedia CIRP. 2019;85:127–32. doi: 10.1016/j.procir.2019.09.043.

[39] Gara S, Tsoumarev O. Prediction of surface roughness inslotting of CFRP. Measurement. 2016;91:414–20. doi: 10.1016/j.measurement.2016.05.016.

[40] Azmi AI, Lin RJT, Bhattacharyya D. Machinability study of glassfibre-reinforced polymer composites during end milling. Int JAdv Manuf Technol. 2013;64(1–4):247–61. doi: 10.1007/s00170-012-4006-6.

[41] Jayaweera N, Webb P. Adaptive robotic assembly of compliantaero-structure components. Robot Comput Int Manuf.2007;23(2):180–94. doi: 10.1016/j.rcim.2006.04.002.

[42] Sreejith P, Krishnamurthy R, Malhotra S, Narayanasamy K.Evaluation of PCD tool performance during machining ofcarbon/phenolic ablative composites. J Mater ProcessTechnol. 2000;104(1–2):53–8. doi: 10.1016/S0924-0136(00)00549-5.

[43] Bolar G, Mekonen M, Das A, Joshi SN. Experimental investi-gation on surface quality and dimensional accuracy duringcurvilinear thin-wall machining. Mater Today Proc.2018;5(2):6461–9. doi: 10.1016/j.matpr.2017.12.259.

[44] Roesch O. Model-based on-line compensation of path devia-tions for milling robots. Adv Mater Res. 2013;769:255–62.doi: 10.4028/www.scientific.net/AMR.769.255.

[45] Kienzle O. Die Bestimmung von Kraften und Leistungen anspanenden Werkzeugen und Werkzeugmaschinen. VDI-Zeitschrift Integriete Produktion. 1952;94(11–12):299–306.

[46] Ahmad J. Machining of polymer composites. Boston, MA:Springer US; 2009.


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