Feasibility Study of Single-Point Incremental Forming for Discontinuous-Fiber CFRP Using Oil-Bath Heating

Although, three-dimensional printing has several advantages, however there are currently many limitations. In particular, printed products using composite materials such as fiber-reinforced plastic have yet to achieve the same mechanical properties as those obtained from conventional manufacturing methods. In addition, fabricating thin plates or thin shell shapes with sufficient strength is challenging. Incremental forming enables high-mix, low-volume production of thin sheets. This method applies incremental deformation to thin sheets, the desired shape is obtained by accumulating the deformation, and no dies are required. Carbon-fiber-reinforced plastic (CFRP) materials have high specific strength. Discontinuous-fiber CFRP is capable of large plastic deformation under appropriate conditions due to the discontinuity of the reinforcement, and its mechanical properties are nearly isotropic due to the random fiber arrangement. The authors focused on this property and studied the application of single-point incremental forming to discontinuous carbon-fiber-reinforced polyamides. In this study, the workpiece was formed by heating it locally to a deformable temperature by the frictional heat between the rotating tool and the workpiece. The forming experiment was also conducted in an oil bath to keep the entire material at a suitable forming temperature. The results showed that the spindle speed affected forming results even in an oil bath and that heating using an oil bath suppressed deviations from the sine law for thickness and wall angle due to elastic deformation.