Optimal process conditions of thin‐wall injection molding of a cellular phone cover were investigated with the consideration of interaction effects between process parameters. L27 experimental tests based on Taguchi's method were performed, and then Cyclone Scanner, PolyCAD and PolyWorks were used to measure the shrinkage and warpage of the thin‐wall injected parts to determine the optimal process conditions. Based on the results of the analysis of variables and the F‐test, interaction effects for each observed factor were determined. The results indicated that the packing pressure was the most important process parameter affecting the shrinkage and warpage of the thin‐wall part. The optimal process conditions were different for the shrinkage and the warpage. This was because during the injection process, the mechanisms affecting shrinkage or warpage were different. Compared with the results obtained with simplified thin‐wall parts in the literature, it was found that the geometry of a real commercial part did affect the optimal process conditions and the order of influence of process parameters. The optimal process conditions determined by Taguchi's method for reducing the shrinkage and warpage were verified experimentally in this work. Polym. Eng. Sci. 44:917–928, 2004. © 2004 Society of Plastics Engineers.

Digital shape reconstruction is the process of creating digital models from physical parts represented by 3D point clouds. The ideal process is expected to provide a boundary representation that is likely to be identical or similar to the original design intent of the object, and requires minimal user assistance. This paper discusses alternative state-of-the-art approaches, where emphasis is put on automatic methods (i) to create complete and consistent topological structures over polygonal meshes; and (ii) extract accurate and properly aligned surface features that yield complete, trimmed CAD models with fillets and corner patches. Problems and recommended solutions will be presented through case studies using industrial parts.

In multi-axis machining of dies and molds with complex sculptured surfaces, numerical control (NC) simulation/verification is a must for the avoidance of expensive rework and material waste. Despite the fact that NC simulation has been extensively used by industries for many years, efficient, accurate, and reliable view-independent simulation of multi-axis NC machining still remains a difficult challenge. This paper presents the use of adaptive voxel data structure in conjunction with the modeling of a universal cutter for the development of an efficient and reliable multi-axis (typically five-axis) simulation procedure. The octree-based voxel representation of the workpiece saves a significant amount of memory space without sacrificing the simulation accuracy. Rendering of the voxel-based model is view independent and does not suffer from any aliasing effect, due to the real-time triangulation of the boundary surfaces using an extended marching cube algorithm. Implicit algebraic equations are used to model the automatically programed tool geometry, which can represent a universal cutter with high precision. In addition, the proposed method allows users to perform error analysis and gouging detection by comparing the machined surfaces with the original computer-aided design (CAD) model. Illustration of the implementation and experimental results demonstrate that the proposed method is reliable, accurate, and highly efficient.