In Hot Wire (HW) cutting of the Polystyrene Foam (PF), one of the rapid prototyping methods, usually tool path must be offset to outside of the profile of final shape larger than the radius of wire. The aim of this process is to avoid over ablation induced by tremendous heat effect, because this effect heavily affects on the accuracy of the final shape and surface finish. Therefore it can be easily understood that to clarify the fundamental mechanism of the forming process based on physical or chemical considerations and to know the amount of removal rate in advance are very important for the precision of the machining system. However, there is little study which discusses this point. Therefore, authors tried to make clear the basic behavior of PF in the HW cutting process by experimental work, and found that the natural convection have an important role. Furthermore, as the first step to estimate the amount of removal rate theoretically, numerical calculations with simple thermal conduction model were carried out. From comparison of the experimental and theoretical results, it can be concluded that in spite of the simple theoretical model, calculated removal width was coincided with the results obtained from experiments. As a result, possibility of the calculation to estimate the appropriate offset value in the hot wire machining was confirmed.
