Potential for process improvement of the rubber glove manufacturing process : an industrial case study
Coagulant dipping constitutes an important part of the rubber glove manufacturing process. Its operation is affected by many variables which dictates the quality of the finished product. Therefore, investigating the controllable factors affecting the quality of the product and process in the presence of noise factors for process improvement is the primary aim of this study. Robust process design for off-line quality control has received much attention in the literature. Application of this design in the rubber examination glove industry as an alternative solution for potential competitive advantage was investigated. The robust design problem is defined in terms of design objectives, controllable factors and noise factors. In this thesis we combined both controllable and noise factors as a single experimental set-up. An L16 orthogonal array was used as it would allow the evaluation of the eight main factors chosen and some of their interactions. The use of fractional factorial reduces the number of runs required. Physical experiments were conducted in the glove manufacturing plant for the case problem. Effects of experimental errors, model assumptions, the experimental design and modelling approaches on the results are discussed. Models capable of predicting the response performance of the process under study are developed and investigated. Experience learnt from the implementation of quality improvement which are human related factors are also addressed in this thesis. From this study we gained a better understanding of the rubber glove manufacturing process. We are therefore in a better position to see what levels of the independent factors will lead to acceptable response values and acceptable variability. This approach allows us to make appropriate compromises between a target value for the response of interest and resulting variance. The additional knowledge were not known before. It could be used as an advantage for the glove manufacturers to better control their processes. The enormous potential benefits that could be reaped from the information gained about the process quantify the efforts for improvements.