A special method of metal extrusion is the Continuous Rotary Extrusion process, also known as the “CRE” process. This continuous process utilises friction generated heat to plasticise the feedstock. It is mainly used for small and medium-sized profiles of aluminium and copper or its alloys.
The process starts with feeding wire rod into the groove of the wheel, which is supported by a solid pressure shoe. The wire rod usually has a diameter between 8 mm and 25 mm. The friction between the groove and the feeding wire rod produces a high temperature and simultaneously a high forming pressure. In the die chamber, an abutment protrudes into the groove of the wheel diverting the plasticised feedstock into the die chamber then leaving the die as a final shaped product. The process can also be carried out with metal powder fed into a suitably sized wheel groove.
The principal item of the plant is the wheel which is highly stressed due to high operational pressures and temperatures. In addition to the high dimensional accuracy of the wheel, the correct selection of the most suitable material and optimum hardness range is essential to achieve a good hot creep strength and to maximize life