Investigation into thermal characteristics of linear hotwire cutting system for variable lamination manufacturing (VLM) process by using expandable polystyrene foam

Abstract

The dimensional accuracy and efficiency of VLM-S, which is a new rapid prototyping process using hotwire cutter and expandable polystyrene (EPS) foam sheet, depends significantly on the thermal fields of EPS foam sheet when the hotwire cuts the sheet. The objective of this study is to investigate thermal effects of the hotwire cutting on the sheets and to find relationships between process parameters in order to obtain optimal conditions for hotwire cutting and improve dimensional accuracy of the process. Several experiments were performed to find the relationships between maximum cutting speed and heat input, and between cutting offset and heat input. Numerical analyses were carried out to investigate the influence of the cutting parameters on temperature distribution around the hotwire and to estimate the amount of the sheet melted away. Moreover, the size of the thermal front as the hotwire is about to lose its stiffness was predicted to propose the optimal cutting conditions. Based on the results, the optimal cutting conditions of the hotwire cutting system for cutting of an EPS foam sheet were found. In addition, the outcomes of the present study were reflected on the fabrication of a spanner shape and a clover punch shape.