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Lightweight materials like Carbon Fiber Reinforced Polymers (CFRPs) present certain challenges, mainly regarding the resultant surface integrity of the holes. Different techniques such as optimized tool geometries, machining techniques and cooling/lubricating techniques have been tested for improving surface integrity on CFRPs. Unfortunately using...
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This research work aims to evaluate the effect of cryogenic cooling on delamination during drilling operations on the carbon fiber reinforced plastic with Al 2024 stack. This research study carefully combines both experimental observations and modeling approaches at two different drilling conditions: one is dry, and the other is cryogenic cooling u...
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... It is possible to influence the size of cutting forces by other parameters such as the process environment or the geometry of the tool. The team of Rodriguez et al. performed an experiment varying the point angle and cooling conditions [19]. Cutting force and torque increase with an increasing point angle of the drilling tool. ...
Current research studies devoted to cutting forces in drilling are oriented toward predictive model development, however, in the case of mechanistic models, the material effect on the drilling process itself is mostly not considered. This research study aims to experimentally analyze how the machined material affects the feed force (Ff) during drilling, alongside developing predictive mathematical–statistical models to understand the main effects and interactions of the considered technological and tool factors on Ff. By conducting experiments involving six factors (feed, cutting speed, drill diameter, point angle, lip relief angle, and helix angle) at five levels, the drilling process of stainless steel AISI1045 and case-hardened steel 16MnCr5 is executed to validate the numerical accuracy of the established prediction models (AdjR = 99.600% for C45 and AdjR = 97.912% for 16MnCr5). The statistical evaluation (ANOVA, RSM, and Lack of Fit) of the data proves that the drilled material affects the Ff value at the level of 17.600% (p < 0.000). The effect of feed represents 44.867% in C45 and 34.087% in 16MnCr5; the cutting speed is significant when machining C45 steel only (9.109%). When machining 16MnCr5 compared to C45 steel, the influence of the point angle (lip relief angle) is lower by 49.198% (by 22.509%). The effect of the helix angle is 163.060% higher when machining 16MnCr5.
... Figure 2 shows the delamination phenomenon that occurs in composite materials. The method for measuring the amount of delamination in composite drilling results is by looking for the delamination factor (Fd) [11] [12]. ...
... Varying the number of layers results in the thickness of the specimen increasing in number of layers, making the fiber composite specimen have strong and brittle properties. Meanwhile, the fewer the number of layers, the more ductile the mechanical properties of the composite will be, so that the elastic modulus value becomes smaller [11]. A graph of the effect of the number of woven fiber composite layers on elastic modulus value can be seen in Figure 6. ...
A composite is a combination of 2 or more different materials. The composite joining process can use adhesives or mechanically by making holes. During the process of making holes in the composite, it can cause delamination in the composite. Delamination and layer thickness greatly influence the strength of hollow composite joints. This research aims to determine the effect of delamination factors and the number of layers on the tensile strength value of the composite. The materials used in this research are polyester resin and woven glass fiber. The method used is vacuum bagging with variations in the number of layers, namely 3 layers, 4 layers, 5 layers, and 6 layers. Tensile testing refers to ASTM D638 standards. Specimens that have been cut according to standards will then be perforated in the center with a hole diameter of 4 mm using a milling machine. The highest tensile strength value was obtained in the 6-layer variation of 237.448 MPa and the lowest value was obtained in the 3-layer variation of 186.221 MPa. The delamination value greatly influences the tensile strength of the composite, where the more layers, the delamination value will decrease and increase the tensile strength of the composite.
... SEM investigations also revealed that the tool geometry was mostly preserved under hybrid conditions with fewer build-up edges and adherence of the workpiece material Pereira et al. [33] Milling The authors claimed that hybrid LCO 2 + MQL is an environmentally friendly technique for milling heat-resistant superalloys. In their evaluation, better performance with respect to cutting force and tool life was realized when cryogenic and MQL alternatives were used together Abedrabbo et al. [34] Grinding The surface integrity of grinded surface of 27MnCr5 steel was evaluated, and it was determined that LN 2 + MQL and LN 2 conditions can favorably reduce microstructural defects and produced better compressive residual stresses thus enhanced the surface quality of machined surfaces Gupta et al. [35] Turning Hybrid LN 2 + MQL showed superior results than dry and LN 2 conditions in a sustainability assessment criteria, which includes the turning cost, carbon emission, total productivity, and energy consumption Rodriguez et al. [36] Drilling The authors proposed that LCO 2 + MQL technique can favorably improve the surface morphology of carbon fiber-reinforced polymer (CFRP) by reducing the generated drilling torque Liu et al. [37] Turning In surface roughness and vibration evaluations, hybrid lubrication CA + MQL outperformed flood cooling in high-speed (300-400 m/min) turning of AISI 304 stainless steel Villarrazo et al. [38] Milling An improvement in tool life of 30% was realized with hybrid LCO 2 + MQL technique when AISI 1045 steel was milled under hybrid and flood environment. The authors claimed that hybrid lubrication is a sustainable approach that can save cost and energy, thus achieving ecological and economic benefits performed in the absence of a cutting fluid, the heat dissipation mechanism will only occur in the chip, tool, and workpiece [63]. ...
Sustainable machining practices including dry cutting, cryogenic cooling (Cryo), and minimum quantity lubrication (MQL) techniques play an essential role in minimizing the extensive utilization of mineral-based cutting fluids, which can harm our ecology and health. However, the insufficient cooling and lubrication competencies of these eco-friendly strategies have some limitations that restrict their implementation in large-scale industrial applications. High-temperature generation in dry environment is associated with rapid tool wear and deteriorated surface quality. MQL at a high cutting speed usually requires better cooling capability; nevertheless, the inefficient lubrication mechanism offered by cryogenic environment affects the metal cutting performance and increases the machining cost. In this regard, hybrid lubrication technique was introduced to utilize the combined benefits of Cryo and MQL strategies for curtailing the thermal–mechanical damage associated with the tool and workpiece material. This paper reviews literature on sustainable hybrid lubrication techniques under three main topics, i.e., (a) Cyo-MQL lubrication fundamentals, (b) active heat transfer mechanisms, and (c) machinability performance in different machining processes, which includes tool life, cutting force, surface roughness, and microstructure characterization. Three data basis Google Scholar, Scopus, and Web of Sciences have been used to select relevant research articles on hybrid lubrication techniques. It is summarized that utilization of hybrid lubrication technique in different machining processes cannot only create a sustainable workpiece environment but can also remarkably improve the surface quality and material characteristics along with extending tool life and reducing cutting force.
... Кріогенне свердління з використанням LCO 2 збільшує сили різання та коефіцієнт розшарування. До того ж, поєднання охолодження LCO 2 і MQL може зменшити розшарування завдяки кращим умовам змащування в зоні контакту інструмент-заготовка [44]. Свердління в середовищі LN 2 усуває те, що низькі температури збільшують розмір отворів у верхній і нижній частині шару композиту до 20 мкм порівняно зі свердлінням без ЗОР за аналогічних режимів різання. ...
У останні десятиліття пакети вуглепластик/титановий сплав набули поширення у виробництві компонентів авіаційної техніки на противагу використанню окремо волокнистих матеріалів та металевих сплавів, що пов’язано з вищими фізико-механічними та експлуатаційними властивостями пакетів у порівнянні зі сплавами. Разом з розширенням сфери застосування пакетів вуглепластик/титановий сплав збільшились і валова частка механічних операцій, що значною мірою пов’язано з необхідністю з’єднання шарів вуглепластику з шарами титанового чи алюмінієвого сплаву. У цьому контексті найпоширенішою операцією механічної обробки є свердління отворів. Одночасне оброблення різних за структурою, хімічним складом та фізико-механічними характеристиками матеріалів пакетів викликає низку викликів як перед дослідниками, так і інженерами в аспекті забезпечення економічної точності та якості отворів у шарах вуглепластику та титанового сплаву. Незважаючи на великий обсяг досліджень зі свердління отворів у пакетах вуглепластик/титановий сплав, всебічне розуміння основних параметрів свердління та їхній вплив на точність та якість отворів є недостатнім. Метою статті є критичний огляд процесів свердління отворів у пакетах вуглепластик/тита-новий сплав та вплив цих процесів на параметри обробки. Для узагальнення сучасних досягнень в галузі обробки пакетів проведено комплексний аналіз літератури. Розглянуті аспекти, які включають вплив режимів різання та технологій механічної обробки на показники якості отворів. Особливу увагу приділено обговоренню параметрів свердління у перехідній зоні шарів пакету, а також впливу різних стратегій і послідовності свердління на результати свердління пакетів вуглепластик/титановий сплав. Зокрема, вказано на поточні недоліки дослідження та означено подальші напрямки досліджень. Стаття спрямована на надання науковому та виробничому співтовариству повного розуміння процесів свердління пакетів.
... As for the drill tool type, compared to the 138° twist drill, the 120° twist drill possesses a promising capacity to thrust the force drop owing to its superior penetration ability. It is known that an increase in tool point angle also increases the average chip thickness and chip cross section [50]. Besides, during drilling with a traditional twist drill, the chisel edge of the tooltip compresses the laminate specimen aside, particularly at the center zone. ...
... As for the drill tool type, compared to the 138 • twist drill, the 120 • twist drill possesses a promising capacity to thrust the force drop owing to its superior penetration ability. It is known that an increase in tool point angle also increases the average chip thickness and chip cross section [50]. Besides, during drilling with a traditional twist drill, the chisel edge of the tooltip compresses the laminate specimen aside, particularly at the center zone. ...
Carbon fiber-reinforced plastics (CFRPs) have been specially developed to enhance the performance of commercial and military aircraft because of their strength, high stiffness-to-density ratios, and superior physical properties. On the other hand, fasteners and joints of CFRP materials may be weak due to occurring surface roughness and delamination problems during drilling operations. This study’s aim is to investigate the drilling characterization of CFRPs with different drilling parameters and cutting tools. Drilling tests were performed with the Taguchi orthogonal array design (L18: 2^1 3^3). Tests were conducted with three levels of cutting speed (15, 30, 45 m/min), three levels of feed rate (0.05, 0.1, 0.2 mm/rev), two levels of drill diameter (3 and 5 mm), and three different types of drills (two twist drills with a point angle of 138° and 120° and one brad drill). Thrust forces were recorded during drilling tests, and afterwards surface roughness and hole delamination were measured. Obtained results were analyzed with Taguchi and two-way ANOVA. The general tendency was that low cutting speed, high feed rate, and small diameter drill caused an increase in thrust force. Surface roughness decreases with increasing tool diameter, decreasing feed, and cutting speed. Delamination factors of the samples dropped depending on decreasing thrust force levels. Remarkably, it is possible to control the delamination factor values via better surface quality. The brad drill and larger point angle have a negative effect on the drilling quality of CFRPs. According to all results, the cutting speed of 45 m/min and feed rate of 0.05 mm/rev using a type II drill having a 120° point angle and 5 mm diameter (12th trial) and the cutting speed of 30 m/min and feed rate of 0.05 mm/rev using a type II drill having a 120° point angle and 3 mm diameter (2nd trial) were determined as optimum drilling conditions.
... Um ângulo menor, diminui a força axial gerada no processo, mas tende a apresentar maior incidência de fibras não cortadas na entrada do furo. Ângulos maiores tendem a promover cavacos com maior espessura, diminuindo a pressão específica de corte, e consequentemente, reduzindo a delaminação (Rodriguez et al., 2022;Voss et al., 2017;Xu et al., 2022). Segundo Colligan e Ramulu (1992), a delaminação gerada no processo de usinagem também ocorre em função da falta de suporte nas camadas superiores e inferiores do laminado, e ainda pelos desgastes da ferramenta de corte. ...
... Chama a atenção ainda, que os piores resultados com a fresa de topo ainda são melhores que todos os gerados pela broca helicoidal. O fato de a fresa de topo reto ter apresentado o melhor resultado pode estar associado à geometria da ponta da ferramenta, visto que suas arestas de corte formam um ângulo de aproximadamente 180°, o que induz menor pressão específica de corte, reduzindo a deformação do furo e a delaminação peel-up (Rodriguez et al., 2022;Voss et al., 2017;Xu et al., 2022). Em relação à rotação, de acordo com Lin e Chen (1996) e Qiu et al. (2018, uma rotação menor tende a promover o aprimoramento das características da furação, fato notado apenas para a fresa de topo. ...
... Nota-se ainda que os maiores valores produzidos com a fresa de topo ainda são menores que todos os gerados pela broca helicoidal, e que os melhores resultados desta foram obtidos na maior rotação (10000 rpm). Estes resultados corroboram com os estudos de Rodriguez et al. (2022), Voss et al. (2017) e Xu et al. (2022, em que ferramentas com menores ângulo de ponta tendem a promover maior delaminação na entrada do furo. ...
Resumo: A utilização de compósitos reforçados por fibra de carbono (CFRP-carbon fiber reinforced polymer) vem crescendo nos últimos anos. O CFRP é comumente aplicado nos setores automotivo, ferroviário, aeroespacial e naval, em função de suas excelentes propriedades mecânicas. Este material é classificado como de baixa usinabilidade em função da sua elevada resistência à tração e ao cisalhamento, presença de fibras abrasivas e sua natureza anisotrópica. Devido à composição estrutural do CFRP e suas características, a furação é um dos processos de usinagem mais comuns para estabelecer ligações mecânicas deste material à outras estruturas. A qualidade do processo é fundamental para permitir adequada montagem, e seu resultado pode impactar diretamente na integridade estrutural e durabilidade do componente. Dentre os defeitos mais comuns, estão a delaminação e a deformação do furo. Em contrapartida, a seleção adequada da geometria da ferramenta e a otimização de parâmetros de corte permitem reduzir a ocorrência desses defeitos. Sendo assim, este estudo traz um comparativo de resultados, na perfuração de CFRP com refrigeração a ar comprimido utilizando uma broca helicoidal e uma fresa de topo reto. Para tanto, foram utilizados três níveis de rotação (6000, 8000 e 10000 rpm) com avanço fixo (0,05 mm/volta), e foram analisados para cada ferramenta de corte o desvio dimensional, a circularidade e as delaminações na entrada e na saída dos furos, totalizando seis etapas. Para cada etapa, foram executados 11 furos. Os resultados indicaram que para as métricas de desvio dimensional, circularidade e delaminação peel-up, a fresa de topo reto apresentou os melhores resultados para as condições de corte aplicadas, enquanto a broca helicoidal foi melhor para a delaminação push-out. Observou-se que esta delaminação poderia ser reduzida com a redução do avanço da fresa e/ou a sua saída do furo sem bloqueio da placa de apoio. Assim, conclui-se que a maior qualidade do furo é obtida com a fresa de topo a 6000 rpm.
... It takes into account all the drilling history of the tool to determine the wear of the cutting tool for the n th hole drilled and for the prediction of the thrust force for the (nþ1) th hole, depending on the drilling conditions and the wear reached at the end of the n th hole [44]. A higher point angle, up to 138 , yielded lower delamination damage and interlayer gap [71] compared with the 90 and double 90 / 130 point angles for PCD drills [167]. Luo et al. [181] developed a force-deformation coupling model to study the formation mechanisms of interface damage during drilling of CFRP/Ti stacks. ...
... Using liquid carbon dioxide (LCO 2 ) leads to an increase in cutting force and delamination factor. However, combining LCO 2 and MQL techniques can decrease delamination because of better lubrication conditions at the workpiece-tool interaction zone [167]. Drilling in liquid nitrogen (LN 2 ) eliminates that low temperatures increase hole size at the top and on the bottom of the composite layer up to 20 mm compared with the dry drilling under the same cutting conditions. ...
CFRP/Ti stacks have attracted considerable attention over the past decades as a promising alternative to individual fibrous composites and metallic alloys due to their improved properties and enhanced structural functions. Mechanical drilling is a compulsory but challenging process to shape these compound stacks to desired dimensions and target quality. Despite a large volume of studies already addressing the conventional twist drilling of CFRP/Ti stacks, a comprehensive understanding of their fundamental drilling mechanisms is still lacking. The present paper aims to report the state-of-the-art advances achieved in the fields of CFRP/Ti machining. Aspects including chip removal, damage formation, mechanical/thermal effects, influences of process conditions, hole quality attributes, and tool wear mechanisms are carefully reviewed. An emphasis is placed on the discussion of the interface drilling behaviors as well as the impacts of different drilling sequence strategies on the machining outputs of CFRP/Ti stacks. The current research limitations and future research perspectives are pointed out. The review paper could provide technical guidance for both scientific and industrial communities to achieve the damage-free drilling of CFRP/Ti stacks.
... Besides having low thermal conductivity, CFRP composite possesses exceptional material anisotropic and non-homogeneous features, high mechanical strength which requires expensive machining tools [15,16]. Moreover, drilling-induced defects such as burr formation, delamination and temperature related damages not only reduce the fatigue strength of the final product but also account for most of the CFRP composite part rejection in service [17,18]. Therefore, to overcome these difficulties, it is essential to understand the drilling mechanism of composite laminates in detail. ...
Carbon fiber reinforced polymer (CFRP) has been in high demand over the last few decades, especially in the aircraft manufacturing industry, due to their superior properties. However, drilling of CFRP materials is more complicated than common metal due to their exceptional anisotropic and non-homogenous features. This unique microstructure often leads to drilling-induced defects such as delamination, thermal damage and burr formation which compromises the structural integrity. Therefore, a good understanding of this composite material is required to realize its full potential. This review paper summarizes the knowledge available in literature on drilling of CFRP and their outcomes are compared comprehensively in a simple way. It covers key aspects such as drilling mechanism, cutting parameters and tool geometries for conventional drilling. Also, drilling-induced damages and potential solutions for those problems are addressed and covered in this paper