esign up to gear size Water screw design from gea B4-VV5A Bevel-helical speed reducer B4

Flender/Flender Gear Units/Bevel-helical speed reducer B4

Table 3.8.9 3 Design Depending on their properties prole, materials may be transformed into differ- ent states and their physical properties may then differ according to their state. 3.5.2 Materials for Bevel Gears Plastic For economic reasons, plastics are used in applications with low require- ments in terms of tooth root and contact strength. Within certain limits, their state canbe further adapted to the requirements prole by means of composite techniques. Sintered metal More heavily stressed gears, which can no longer be made of plastic, are produced in sintered process if the number of parts is sufcient tojustify it. The higher load capacity, when compared to plastic, must be contrastedwith greater mass. Sintered gears are accordingly to be classied between plasticand steel gears in terms of their power-to-weight ratio. Grey cast iron and cast steel They are less widely-used variants as gear mate- rials. They have low to medium load capacity compared to gears made from steel.In general, these materials are easy to machine. Depending on the temperaturecontrol and cooling conditions in the casting process, it is possible to adjust thefailsafe running properties and heat treatability of the material. Structural and tempering steels If the gear geometry does not allow casting, or if the requirements prole demands higher-quality materials, metal-cutting processesmust be applied where structural and tempering steels can be used; they show high machinability and medium load capacity, and are characterized by high toughness and lower costs than those of higher quality steels. Surface-hardened tempering steels For higher requirements in contact strength, the tooth surface load capacity must be improved by means of heat treatment.Table 3.8 Requirements and properties proles Bevel gear requirements prole Material properties prole Cost-effectiveness Material costs Process-reliable manufacturing Alloy compositionTechnical properties: Castability Stiffness Weldability T