Soft composite materials are used for a functional film for a thermal interface material. The surface of this functional film must be flatter and thinner, and contacting fillers to have a better thermal conductivity. Cutting would meet these requirements to slice such soft materials. Soft composite materials consisting of acrylic rubber bulk and graphite fillers were prepared and sliced into films (1mm thickness) as thermal interface materials by developed cutting method. Measurements of curl radius and cutting forces were conducted on the orthogonal cutting experiments. It was found that the following three strategies were effective for reducing curl of chip and cutting force : (1) higher operating temperature, (2) slower cutting speed, and (3) larger tool rake angle. This result suggested a useful method for the effective slicing by controlling the cutting conditions.