The materials that are used for gear manufacturing depend massively on the conditions that the gears will be operating under, conditions like wear and noise etc. Gear manufacturers use metallic or non-metallic materials.
The Metallic materials used in gear manufacture are normally available in cast iron, steel and bronze. Steel is used when there is a need for a high strength design. But cast iron is mainly used because of its good wearing properties, excellent machineability and the ease that complicated shapes can be created due to the casting method.Castings are created by pouring molten metal into a mould and once the metal as cooled it takes the shape of the mould.
The non metallic, materials used are generally wood, rawhide, compressed paper and synthetic resins like nylon. These types of materials are generally used when there is a need for the reduction in noise from the gears.