Current understanding of rubber compounds extrusion is reviewed in detail. By analysing the extrusion process as a series of sequential unit operations, the problem is split in two main parts: the screw component and the die component. Recent experimental data demonstrate that rubber extruders are operated in ‘starvation’ situations. i.e. the screw is incompletely filled: consequently the pressure build-up arises only in the screw head region. With respect to the variety of equipment used in the works reviewed. such behaviour might be considered as typical of rubber extrusion. Attention is drawn to the short dies used in practical rubber extrusion and the associated important elongation flow component. Wall slippage is analysed as a key component in rubber extrusion. with particular emphasis on its effect on converging flow in the short die of industrial practice.
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