Investigation into development of variable lamination manufacturing using expandable polystyrene foam

Abstract

Rapid prototyping (RP) technologies have been widely used to reduce the lead-time and development cost of new products. Most of the developed thin-layered RP technologies have disadvantage due to their working principles: large building time, stair-stepped surface of a part and additional time consuming post-processing. In addition, it requires high cost to install, operate and maintain the RP apparatuses. The thick-layered RP technologies employ mostly very thick layers thicker than 10 mm, expensive cutting systems and fully manual or extremely large automatic manipulation systems. Hence, a new effective RP process is needed for RP technology innovation of RP and to meet the needs of the RP market. In the present work, a new effective rapid prototyping process, Variable Lamination Manufacturing Process using expandable polystyrene foam (VLM-S), has been developed to improve building efficiency including a building time and cost, to extend capabilities of the current RP technology toward the fabrication of practical parts covering the volumetric range from small-and-medium size and to medium-and-large size, to minimize the post-processing, and its equipment cost. In addition, thermal characteristics of hotwire cutting for expandable polystyrene foam (EPS) is investigated to improve the quality of parts and to estimate the optimal cutting conditions. VLM-S process has several advantageous features such as thick layers with a thickness of less than 4 mm, sloping surfaces with the first order approximation between top and bottom surfaces of each layer, the concept of unit shape layer (USL) and unit shape part (USP), and a building sequence in that it performs stacking and bonding after cutting. The thick layer and the sloping surfaces have reduced the building speed, while maintaining the dimensional accuracy in a reasonable range. Using the concept of USL and USP, the problems of cutting for a multiply connected domain have been overcome. The majority...