Characterization of Cutting Forces in Milling of Unidirectional and Random Fiber Composites

Abstract

There is an ever increasing demand for materials with High strength-weight ratio (Specific strength), corrosion resistance in the current aerospace, automotive and consumer industries apart from other technical applications. Among the various materials available with the required superior material properties , Carbon Fiber Reinforced Polymer (CFRP) is one of the most widely used material. It is extremely strong and light in weight with fibers made of carbon. It is a unidirectional composite. Molding is one of the most used method of manufacture. Most processes only produce a near net shape but machining is still required in order to get the final dimensions and shape. However, major challenges are associated with the finish machining by trimming and or drilling of the CFRP material. Some of these are delaminations, fiber pullouts and a short tool life due to the abrasive nature of the fibers and the inhomogeneous nature of the material. Two types of cutting by milling process are undertaken, namely edge trimming and end milling so the forces can be investigated. The effect of cutting parameters namely, Speed , Feed, Depth of cut and angle of cutting on the milling forces has been analyzed using statistical design of experiments (DOE). The cutting has been done in various orientations with respect to the fiber direction in order to see the effect of the orientation on the milling forces. HexMC is one of the newly emerging composite materials. It has a very high strength value due to its random fiber orientation compared to other unidirectional composites. The same DOE of cutting parameters mentioned above have been used to analyze their effect on the milling forces on this composite. Cutting forces in CFRP found to decrease at high speeds and low feeds and in HexMC found to be influenced by the type of cutting operation.