The best material for a small straight bevel gear depends on your application. Steel is the most common choice for strength and durability. 20CrMnTi is a popular material because it can be carburized to a hard surface of 58-62 HRC while keeping a tough core. This gives good wear resistance and good impact strength. 40Cr is another common choice. It is cheaper than 20CrMnTi but does not get as hard. For light-duty applications, 45 steel without carburization may be enough. For very high volume, low-cost applications, powdered metal is a good choice. Powdered metal gears are made by pressing metal powder into a mold and then heating it. They are cheaper than cut steel gears but not as strong. For very light loads, plastic gears work well. Nylon, POM, and other engineering plastics are used in toys, small printers, and consumer electronics. Plastic gears are quiet, lightweight, and do not need lubrication. However, they cannot handle high loads or high temperatures. Brass is sometimes used for small gears in instruments and watches. Brass is easy to machine, looks good, and resists corrosion, but it is not strong. For most industrial and power tool applications, 20CrMnTi with carburization is the best balance of strength, wear resistance, and cost. For lighter applications, save money with 40Cr or powdered metal. For the lightest applications, use plastic. The material choice is always a trade-off between cost, strength, and application requirements. There is no single best material. Match the material to the job, and your small straight bevel gear will perform well.