Through-shaft cooling improves product quality and is a standard feature on Baker Perkins twin-screw extruders. Uniquely, the cooling water channels on Baker Perkins extruders extend through the gearbox to increase the reliability and effectiveness of the seals.
Cooling water channels in the centre of the shafts draw heat from the screw elements to help maintain the optimum processing temperature, particularly at the tips of the screws, where hot-spots can develop. Heat dissipation is a particular problem in this area, where speed and friction are at their highest and the metal is at its thinnest. Cooling the centre of the shaft increases the rate of heat transfer from the tip to the core of the screw and to the shaft. This reduces pre-melt on the feed screws, and eliminates pre-curing of product in the extruder barrel, to ensure higher quality and greater consistency.
Water is fed from the rear of the gearbox, rather than introduced at the couplings. The advantage of this through-shaft method is that the water connections are in a completely unstressed area which guarantees a strong, drip-free seal, eliminating the risk of leakage. This increases reliability and cleanliness, as well as reducing maintenance.