Abstract: Vulcanization cycle times are substantially reduced in the injection molding of rubber compounds by forcing uncured, substantially unheated highly viscous rubber compounds through a thin flow channel upstream of the mold without supplying heat to the compound by conduction from an external source at any point prior to the mold. The compound is autogenously and quickly heated by the energy generated from the mechanical working of the compound under conditions of shear in the channel. The shearing action substantially reduces the compound's viscosity and increases its temperature above the critical residual scorch range as it passes through the channel. The downstream product is a rubber compound of significantly reduced viscosity having a substantially uniform temperature throughout, which is injected into a mold in a continuous flow and vulcanized.