Investigating Bowing of Hot Wire during cutting of EPS

During hot wire cutting of expanded polystyrene foam blocks, it is observed that the wire adopts a characteristic bow shape as the cutting proceeds. Due to this the cutting process loses its precision. The present study investigates the factors responsible for the bowing phenomenon via a series of experiments involving variations in current and wire feed rate. Based on the contribution of these two parameters, a regime of 'No Bowing' has been identified. This regime will be useful to a process planner to select working conditions which would allay bowing and build more precise prototypes. In this regard, the role of kerf width is also examined. An analytical model is suggested to quantify the bowing effect at different current and feed rates under steady state cutting conditions. Further a novel finding to predict the influence of gases in bowing has been analyzed and quantified.