Experimental Study of Progressive Compression Method of Resin Delivery in Liquid Composite Molding

Abstract

A new technique of resin delivery, which we refer to as the progressive compression method (PCM), has been invented to reduce filling time associated with the vacuum assisted resin transfer molding (VARTM) process. In the method, the bag is divided into several segments. During infusion, all segmented bags are pulled away from the preform by the vacuum. Hence, resin is easily infused into the loose preform. Once enough volume of resin is infused, the vacuum within the segmented bags is released in a step-wise manner. The atmospheric pressure of the heated air is progressively applied on the segmented bag that is inflated to compact the wetted preform and drive the resin through the remaining dry preform. The resin flow is enhanced since the dry preform remains loose during the filling process. The research aims to investigate the effect of seven process parameters on the PCM complete filling process by applying Taguchi’s method. All chosen factors are designed with two levels. Experimental results show that the predicted optimum settings are higher vacuum pressure, more compression segment, later initiation of the next compression segment, higher air temperature, later introduction of the heated air, lower initial height of the cavity and less excess infused resin for reducing the filling time. Compared with typical VARTM without flow enhancement, PCM at the optimum settings reduces the filling time by 72.85%.