Gears are components of the power transmission system. All driven machine elements are controlled by gears that govern torque, speed, and rotation direction. There are many intricacies to the different types of gears. In fact, the selection of gear types is not an easy process. It depends on many considerations. Influencing factors include physical space and shaft arrangement, gear ratio, load, accuracy and quality level.
Many gears are created using various materials and with varying performance criteria depending on the industrial use. These gears come in a variety of capacities, sizes, and speed ratios. The major function, however, is to convert the prime mover's input into an output with high torque and low RPM. These gear families have applications ranging from agriculture to aerospace.
Gearing Materials
Many different types of steel, bronze, cast iron, brass, ductile iron, aluminum, powdered metals, and polymers can be used to make gears. Steel is the most prevalent and attractive of these materials, giving a winning combination of high strength-to-weight ratio, good wear resistance, the ability to improve physical qualities through heat treatment, and a competitive price.
High-priced materials may not guarantee superior gear. Aluminum, brass, bronze, polymers, phenolic materials, powdered metals of various compositions, or stainless steel may be required for some applications. Gear materials are classified into two types: metallic and non-metallic. Polymers, elastomers, ceramics, glass, and composite materials are the five basic types of nonmetallic materials. Metallic materials are classified into two types: ferrous metals, which include steel, and non-ferrous metals, which include bronze and aluminum alloys.
To meet these essential elements, a wide range of materials are accessible. The materials used in gear can range from wood to modern synthetic materials, as well as ferrous metals, non-ferrous metals, powdered metals, and plastics. Stone-made ancient gears have also been discovered. The material used influences the load carrying capability, strength, pitting resistance, life, and cost of the gear.
How to Select a Gear Material
First, the gear material should be chosen based on the application's function. The design of a precisely made gear will fail miserably if the material is not suitable for the needed duty. The material chosen will have an impact on the production process.
The decision will be based on service, manufacturing, and economic needs. Gears, simply put, transmit power or motion. Steel is used in the great majority of power transmission gears. Steel worm gears for use with bronze gears and plastic for power reduction are the exceptions. Most gears are anticipated to carry heavy loads and will require heat treatment to improve strength and wear resistance. Plastic or non-ferrous materials are commonly used to make motion-only gears.
The selection of gear material is difficult and must be tied to the application's unique load and life requirements. The material compatibility, chemical composition, composition, mechanical qualities, and cost of the mating gear must all be considered. Corrosion resistance and electrical or magnetic properties may be required depending on the gear application material.
