Generation of cutting path data of linear hot-wire cutting system for variable lamination manufacturing

Abstract

A new effective thick-layered RP process, Transfer type Variable Lamination Manufacturing using expandable polystyrene foam (VLM-ST) has been developed to reduce building time, to decrease the stair-stepped effect of parts, to minimize post-processing with thick layers and sloping surfaces. VLM-ST employs a 4-axis synchronized automatic hotwire cutter with the parallelogram mechanism and expandable polystyrene foam sheet with the high packing density. The VLM-ST process is divided into a semi-automatic VLM-ST process and a full-automated VLM-ST process according to the stacking method. In the VLM-ST process, a material in the form of a plate is cut into a Unit Shape Layer (USL) or an Automated Unit Shape Layer (AUSL) with thick layers and sloping surfaces by a 4-axis automatic synchronized hotwire cutter according to the cutting path data generated from a CAD model. Each USL or AUSL is then manually or automatically bonded and built up to fabricate a 3D part. The VLM-ST process requires the new method to generate the cutting path data suitable for a newly devised 4-axis synchronized hotwire cutter. The CAD/CAM system for VLM-ST, which is named the VLM-Slicer, includes a software to automatically create 3D toolpath data from 3D CAD model data for the VLM-ST apparatus. In this study, the method for generating the cutting path data of the linear hotwire cutter for the VLM-ST process has been developed. The method to generate cutting path data consists of the CAD process to produce the mid-slice from the STL file and the CAM process to produce the USL or AUSL from the mid-slice. The VLM-Slicer has been implemented by integrating these CAD and CAM processes. The CAD process consists of four steps: STL file input, 2D layer slicing, surface reconstruction, and generation of mid-slice. A 3D CAD model is converted into a triangular-faceted file format, the STL file. The triangular facets of the STL file are imported. The facets of the STL file are sliced into layers wit...