Improving Rubber Mixing Performance of Hot Water Bag Compound

摘要

A rubber factory in India encountered extensive amount of rework at the rubber mixing stage for one of its medicare products, the hot water bag. The scorch time and the optimum cure time of the rubber-mixing compound were the potential product parameters for which this rework took place. Regression analysis shows that the process parameters, the temperature of the dispersion kneader and the temperature of the open mill, with adjusted R~(2) values of 79.9 and 89.5percent, respectively can predict both the scorch time and the optimum cure time. Subsequently analyzing the multiple linear regression equation for optimum cure time, which is the key process output variable, with the help of linear programming has arrived at the optimum levels of these temperatures. Besides this, analysis of variance for scorch time has shown that the mixing technique of the workers is not identical. Duncan's multiple range tests has revealed operator group 3 as the best performer for scorch time. Bartlett's test has revealed inequality of variances of four operator groups for optimum cure time. This substantiated the training need of the concerned operators. The study has resulted in reduction of the extent of rework from 80762 to 17865 PPM. Naturally this substantial reduction in rework will reduce the process cycle time and cost of production immensely.