SUGAR MILL DRIVES-THE LATEST IMPROVEMENTS IN GEAR AND PINION MANUFACTURING TECHNOLOGY

THIS paper presents new designs, materials, heat-treatments, lubrication and insitu gear profile refurbishment procedures of gearing, as related to the sugar industry. Representing the current state of the art in power transmission, the following are all applicable to sugar industry mill and diffuser drives: (1.) Use of AGMA grade 2 forged material in the manufacture of fabricated gears. The use of this special material improves gear performance and allows for the more economical production with shorter lead-times of large fabricated gears. (2.) Application of tooth-by-tooth full contour induction hardening of gears and pinions to achieve case depths of up to 10 mm with hardnesses of up to 56 Rockwell C. (3.) A surface hardening carburising process which produces a higher hardness than previously achievable. Pinion teeth in the hardness range of 62 Rc have now been produced through the introduction of precipitated carbides during the process into the carburised surface layer. As the surface hardness increases the wear rates of gear and pinion teeth decreases and a longer fatigue life cycle is achieved. (4.) Planetary mill drives, multi-stage gearboxes shaft mounted to individual rolls which can greatly reduce downtime and operating costs. (5.) Modern lubricants, which extend the lifetimes of new and existing gear-sets by providing a reliable barrier between the mating gears during service. (6.) In-situ gear reconditioning procedures that use a combination of new hardened pinions, skilled hand re-working of the gear teeth, and application running-in lubricant. Highly successful results have been achieved to extend the life of existing gearing, which otherwise would have required costly replacement. These developments are discussed in conjunction with the best practices of gear and pinion manufacture, which have seen exceptional results achieved to the benefit of the sugar industry.