Towards automatic shape modification in injection-moulded-plastic-part design

Injection-moulded-plastic-part design must ensure that the part can be manufactured to the desired quality level by the injection moulding process. Simulation software has been widely used in industry to assess mouldability and measures of quality. However, it cannot be used to improve a design directly. Design modifications must be performed by the designer after evaluation of the simulation results. Based on the authors' previous work on injection moulding CAD-CAE integration, this paper explores the strategies and methods for automatic-part-shape-modification to attain a desired part quality. An enhanced CAD-CAE integration model is developed. This model is used to specify the shape-modification variables, as well as the mouldability and other quality measuring criteria. The shape modification variables include positional and sizing parameters of each individual feature, as well as those associated with the part, such as part thickness. With this information, an iterative process of part-shape modification and execution of simulation subroutines is carried out automatically, and the results are verified and evaluated. Optimal shape, according to the specified criteria can thus be derived from the evaluation results. A software prototype has been developed. A design case study is presented to illustrate and demonstrate the usefulness of the proposed strategies and methods.