Development of a modular, reconfigurable end effector for the plastics industry : a case study

Abstract

A common problem in large manufacturing companies in the plastics industry is the need to handle mass produced injection-moulded items in the presence of a high degree of variety between batches. In this work, we address a problem being faced by such a company, where different batches of freshly-produced units need to be unloaded from the injection moulding machines. The products need to be grasped and relocated, and the runners disposed of. The number of identical units produced simultaneously by each single mould varies between two and sixteen, and the company makes use of around four hundred different moulds. We have developed a single modular end effector that can be easily reconfigured for the different moulds used by the company, and that also caters for future product designs. We present the detailed design of the new solution, including a function analysis derived from the existing process, a new product design specification, and a quality function deployment exercise. This is followed by the generation of a number of conceptual solutions to the problem, and the evaluation of the alternative concepts using morphological charts, failure mode and effect analysis, and a decision matrix. We present also a detailed embodiment design of the selected concept, and report on prototype development, evaluation and testing. Finally we discuss potential improvements through the use of the new system, and extrapolate the results of this work to more general applications where an end effector is required to carry out simultaneously several different but well defined functions in the presence of high variety.