Manufacturing in blow molding: Time reduction and part quality improvement

In this work, a concurrent engineering approach was applied to the development of a plastic dumbbell, a part used in the recreational sector. The design goal for the part was to reduce the overall weight and to improve the thickness distribution. Simulation of the extrusion blow moulding process and preliminary experimental trials were performed concurrently to assist in the development of the part. Once the numerical modelling of the part was done, improvement of the production process was performed based upon the desired objective function, i.e., a uniform part thickness distribution and/or minimal part weight. The optimisation was performed in two sequential steps, weight optimisation then thickness optimisation, by the systematic manipulation of the operating conditions, such as the parison dimensions. A process modelling methodology was employed to demonstrate the reduction in the part development time using the new model-based approach. Results showed that span time for the part development cycle could be reduced by approximately 60%, while the actual man-hours could be reduced by approximately 30% using a concurrent engineering approach.