Model for the continuous impregnation of fibre tows in resin baths with pins

A simple model, based on lubrication theory, is proposed to describe the process by which impregnation takes place when tows of fibre are drawn over cylindrical pins in the presence of resin. The model proposes four distinct flow regions: the entry zone, the impregnation zone, the contact zone and the exit zone. The impregnation zone, where the entrained film of resin is pumped into the fibre tow, occupies a relatively small proportion of the wrap length. The contact zone results in substantial tension build-up in the tow but does little to improve impregnation. The model has been shown to describe successfully the forces measured when tows of glass are drawn through nylon 66 resin.