Composite materials are widely employed in the naval, aerospace and transportation industries owing to the combination of being lightweight and having a high modulus of elasticity, strength and stiffness. Drilling is an operation generally used in composite materials to assemble the final product. Damages such as the burr at the drill entrance and exit, geometric deviations and delamination are typically found in composites subjected to drilling. Drills with special geometries and pilot holes are alternatives used to improve hole quality as well as to increase tool life. The present study is focused on the drilling of a sandwich composite material (two external aluminum plates bound to a polyethylene core). In order to minimize thrust force and burr height, the influence of drill geometry, the pilot hole and the cutting parameters was assessed. Thrust force and burr height values were collected and used to perform an analysis of variance. The results indicated that the tool and the cutting speed were the parameters with more weight on the thrust force and for burr height they were the tool and the interaction between tool and feed. The results indicated that drilling with a pilot hole of Ø4 mm exhibited the best performance with regard to thrust force but facilitated plastic deformation, thus leading to the elevation of burr height, while the lowest burr height was obtained using the Brad and Spur drill geometry.

Concomitantemente necessidade de desenvolvimento de materiais com qualidades superiores surge a necessidade de processar estes novos materiais, apresentando características e/ou dificuldades para a fabricação de componentes. Neste sentido, os materiais compósitos apresentam diversas características, como baixo peso, rigidez e resistência elevada, que permitem o uso em diversas áreas da indústria moderna. Os materiais sanduíche são um tipo de compósito estrutural e apresentam basicamente 2 faces e um núcleo. Para se alcançar produtos com as qualidades desejadas, são utilizados diferentes processos de fabricação, dentre eles a usinagem. A operação de furação é uma das mais utilizadas para a junção de materiais. Diversos problemas podem decorrer da mesma, como por exemplo, delaminação, erro de circularidade e a presença de rebarbas. Neste sentido, o presente trabalho teve por objetivo a determinação das condições ótimas de corte, por meio do Método Taguchi, para a furação de um material tipo sanduíche, constituído de alumínio e polietileno. Foram utilizados três tipos de ferramentas, três velocidades de corte e três avanços. As condições de corte ótimas obtidas foram estabelecidas considerando a menor força de avanço, menor altura da rebarba e menor diâmetro máximo.Palavras-chave: Furação. Material Sanduíche. Método Taguchi.Application of the taguchi method in the optimization of the parameters of the drilling operation of a sandwich materialAbstractConcomitantly with the need to develop materials with superior qualities arises the need to process these new materials, presenting characteristics and / or difficulties for the manufacture of components. In this sense, the composite materials have several characteristics, such as low weight, rigidity and high resistance, which allow the use in several areas of modern industry. Sandwich materials are a type of structural composite and have basically two faces and a core. In order to achieve products with the desired qualities, different manufacturing processes are used, among them machining. The drilling operation is one of the most used for the joining of materials. A number of problems may occur, such as delamination, circularity error and burrs. In this sense, the present work has the objective of determining the optimal cutting conditions, by means of the Taguchi Method, for the drilling of a sandwich type material, made of aluminum and polyethylene. Three types of tools were used, three cutting speeds and three feeds. The optimum cutting conditions obtained were established considering the lower feed force, lower burr height and lower maximum diameter.Keywords: Drilling. Sandwich material. Taguchi Method.