Effect of machining parameters on the mechanical properties of high dosage short carbon- fiber reinforced composites

The machinability of polymer matrix composites with fibers strongly depends on the type of fiber and dosage in question, having a high influence on the selection of tools and cutting parameters. The cutting temperature depends of rotation speed and the feed cutting tools and is significantly influencing on the quality of the machined surfaces and tool life. This paper presents the results of a current study concerning the effect of the rotation-cutting speed on the cutting temperature, roughness and tensile strength of short carbon fiber reinforced epoxy composites, potentially used in automotive and aeronautic industries. Composite plates were manufactured by compression molding, using short carbon fibers with 0.5 mm and 6 mm length. The increasing of the rotation-cutting speed increases significantly the temperature generated in the tool and slightly increases surface roughness. Tensile strength and Young閴s modulus are little sensitive to drilling speed. However, above 3000 rpm it was observed significant loss of stiffness, associated with the developed temperature in the machining process

Response of fabric insert injection overmolding pp based composites subjected to single and muti-impact

This paper presents the results of a current study on the development and impact response of composite plates manufactured by injection overmolding on the two sides of a single reinforcement fibre mat. The injection polymer is a talc-filled polypropylene, nowadays used for structural purposes. Three configurations with different insert fibre mats were used: Kevlar, biaxial and multiaxial glass fibre mats. The parameters studied were the fibre mat type and the impact energy. For single impact tests, it was concluded that the highest impact energy required to achieve impactor perforation is obtained with Kevlar insert, while the highest percentage of energy recovered is achieved with biaxial glass fibre netting. Kevlar insert also allows for the maximum impact stiffness. For the multi-impact tests, the recovered energy and the dynamic stiffness show the same tendencies of the single impact tests. On low energy impacts, the effect of the insert fibre and of the previous impact are quite reduced, while for impact energies above 6J, previous impacts reduce significantly the recovered energy and the impact energy for which the perforation was achieve