What materials are commonly used for manufacturing gears?

The correct answer identifies the most commonly used materials for manufacturing gears as metal, plastic, and composite materials. Each of these materials has distinct advantages that make them favorable for gear production.

Metal, especially steel and its alloys, is widely used due to its strength, durability, and ability to withstand heavy loads and high wear. Gears made from metals can be finely machined to achieve precise dimensions, which is essential for their proper functioning in mechanical systems.

Plastic is also a popular choice because it is lightweight, resistant to corrosion, and can be molded into complex shapes more easily than metal. Additionally, certain engineering plastics offer good mechanical properties making them suitable for applications requiring less load.

Composite materials combine the advantageous properties of multiple components to create gears that can perform well under specific conditions, such as high temperature or corrosive environments. Composites can also reduce weight while maintaining strength, which is crucial in applications where reducing overall mass is beneficial.

In contrast, options involving wood, glass, rubber, or paper are less common or suitable for gear applications. These materials lack the mechanical strength and wear resistance typically required for effective gear operation in most machinery. Thus, they do not meet the performance requirements necessary for gears in various industrial contexts.