Damage Quantification for the Machining of CFRP: An Introduction about Characteristic Values Considering Shape and Orientation of Drilling-induced Delamination

Lissek, Fabian; Tegas, Jacqueline; Kaufeld, Michael

doi:10.1016/j.proeng.2016.06.632

Cited by 34 publications

(20 citation statements)

References 36 publications

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“…Delamination at the exit generally shows up as the crack in the direction of fibers during drilling CFRP . The crack at the exit starts in the direction of fibers just before the chisel edge achieves the last layer .…”

Section: Resultsmentioning

confidence: 99%

Effect of drill flute direction on delamination at the exit in drilling Carbon Fiber Reinforced Plastic

et al. 2018

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Drilling holes on Carbon Fiber Reinforced Plastic components is inevitable for mechanical assembly in the aerospace field. Delamination at the exit frequently occurs and substantially reduces the service life of components. Drill flute direction is one of the main factors affecting delamination at the exit. The article aims to study the effect of drill flute direction on delamination and further to guide the suitable choice of drill flute direction. Comparative experiments are performed in drilling Carbon Fiber Reinforced Plastic for the drills with different drill flute directions, when a small cutting edge radius is involved. Based on the experimental results, the effects of drill flute direction on the thrust force, force state of the uncut fibers at the exit, and delamination propagation at the exit are obtained. Meanwhile, the phenomenon that delamination at the exit varies with the drill flute direction significantly is explained from aspects of thrust force and force state of the uncut fibers at the exit. The drill with left hand helix owns the most serious delamination at the exit among the tested drills because of its high thrust force and serious tearing function for the uncut fibers at the exit. POLYM. COMPOS., 40:E1434–E1440, 2019. © 2018 Society of Plastics Engineers

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Section: Resultsmentioning

confidence: 99%

Effect of drill flute direction on delamination at the exit in drilling Carbon Fiber Reinforced Plastic

et al. 2018

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“…In case improper machining technology is applied when machining CFRPs, many micro-and macro-geometrical damages can be generated easily: such damages include delamination [6,7,[14][15][16][17][18][19][20][21][22][23][24], uncut fibres and pull-outs [13,[25][26][27][28][29][30][31] as well as microcracks on the machined surfaces [30,[32][33][34]. In order to minimize the above-listed damages, there are many process and technological parameters that have to be optimized including (i) the geometry and coating of the cutting tool [18,33]; (ii) the cutting speed, feed rate and the depth of cut [7,18,35]; (iii) the tool path [7,13,32]; (iv) the cooling [36][37][38][39]; and (v) the type of support plate [40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Comparative analysis of wobble milling, helical milling and conventional drilling of CFRPs

Pereszlai

Geier

2020

Int J Adv Manuf Technol

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Due to its excellent specific mechanical properties, carbon fibre-reinforced polymer (CFRP) composite is a widely used structural material in the aerospace industry. However, this material is difficult to cut, mainly due to its inhomogeneity and anisotropic features and because of the strong wear effects of its carbon fibres. In the scope of aerospace industrial uses of this material, thousands of holes have to be machined for purposes of assembly. Nevertheless, conventional drilling technologyeven if special drilling tools are usedis only moderately able to manufacture good quality holes. Wobble milling is a novel advanced hole-making technology, which has been developed to minimize machining-induced geometrical defects like delamination or uncut fibres. The main objective of the present paper is to compare wobble milling, helical milling and conventional drilling technologies concerning unidirectional CFRPs. In addition, the kinematics of wobble milling technology is discussed in detail. In the scope of this paper, numerous machining experiments were conducted in unidirectional CFRPs: herein the impact of the type of cutting tool and of process parameters on the quality of machined holes are analysed and discussed (diameter of holes, circularity error and characteristics of uncut fibres). During these investigations, experimental data were evaluated with the help of digital image processing (DIP) and with the help of analysis of variance (ANOVA) techniques. Experimental results show that the amount of uncut fibres can significantly be minimized through the application of wobble milling technology.

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“…The delamination phenomenon is closely influenced by the drilling process parameters [15][16][17][18][19][20]. In [21,22], an excessively high thrust force is reported as the main process parameter responsible for catastrophic tool failure and extended delamination damage.…”

Section: Introductionmentioning

confidence: 99%

Smart Multi-Sensor Monitoring in Drilling of CFRP/CFRP Composite Material Stacks for Aerospace Assembly Applications

et al. 2020

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Composite material parts are typically laid out in near-net-shape, i.e., very close to the finished product configuration. However, further machining processes are often required to meet dimensional and tolerance requirements. Drilling, edge trimming and slotting are the main cutting processes employed for carbon fiber-reinforced plastic (CFRP) composite materials. In particular, drilling stands out as the most widespread machining process of CFRP composite parts, chiefly in the aerospace industrial sector, due to the extensive use of mechanical joints, such as rivets, rather than welded or bonded joints. However, CFRP drilling is markedly challenging: due to CFRP abrasiveness, inhomogeneity and anisotropic properties, tool wear rates are inherently high leading to superior cutting forces and detrimental effects on workpiece surface quality and material integrity. Damage such as delamination, cracks or matrix thermal degradation is often observed as the result of uncontrolled tool wear or improper machining conditions. Sensor monitoring of drilling operations is, therefore, highly desirable for process conditions’ optimization and tool life maximization. The development of this kind of automated control technologies for process and tool state evaluation can notably contribute to the reduction of scraps and tool costs as well as to the improvement of process productivity in the drilling of CFRP composite material parts. In this paper, multi-sensor process monitoring based on thrust force and torque signal detection and analysis was applied during drilling of CFRP/CFRP laminate stacks for the assembly of aircraft fuselage panels with the scope to evaluate the tool wear state. Different signal-processing methods were utilised to extract diverse types of features from the detected sensor signals. A machine-learning approach based on an artificial neural network (ANN) was implemented to make smart decisions on the timely execution of tool change, which is highly functional for CFRP drilling process automation.

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Damage Quantification for the Machining of CFRP: An Introduction about Characteristic Values Considering Shape and Orientation of Drilling-induced Delamination

Cited by 34 publications

References 36 publications

Effect of drill flute direction on delamination at the exit in drilling Carbon Fiber Reinforced Plastic

Effect of drill flute direction on delamination at the exit in drilling Carbon Fiber Reinforced Plastic

Comparative analysis of wobble milling, helical milling and conventional drilling of CFRPs

Smart Multi-Sensor Monitoring in Drilling of CFRP/CFRP Composite Material Stacks for Aerospace Assembly Applications

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