The steel is used for high strength worm gears (worm wheel) and steel could be plain carbon steel or alloy steel. The metal gears are generally heat treated to be able to combine properly the toughness and tooth hardness.
The phosphor bronze is widely used for worms drive so as to reduce wear of the worms which is excessive with cast iron or steel.
Worm gear sets are usually used to reduce speed and enhance torque. Because the worm drive undergoes more contact pressure cycles compared to the worm gear, the worm travel is normally of a stronger material.
• Cast iron provides strength and ease of manufacture.
• Cast steel provides a lot easier fabrication, strong doing work loads and vibration resistance.
• Carbon steels are economical and strong, but are susceptible to corrosion.
• Aluminum is utilized when low gear inertia with some resiliency is necessary.
• Brass is inexpensive, easy to mold and corrosion resilient.
• Copper is easily formed, conductive and corrosion tolerant. The gear’s durability would increase if bronzed.
• Plastic is inexpensive, corrosion resistant, noiseless operationally and may overcome missing the teeth 
or misalignment. Plastic is less robust than metallic and is susceptible to temperature changes and chemical substance corrosion. Acetal, delrin, nylon, and polycarbonate plastics are normal.
This 27 tooth brass worm gear will be used in combination with a worm gear to produce a 27:1 reduction in speed while also changing the orientation of the rotating axis by 90 degrees. This gear fastens to a 1/4″ shaft using a specialized 1/4″ D-hub to be utilized with 1/4″ D-shaft.
The manufacturing methods of worms are roughly divided among cutting, heat treated and ground after cutting and rolling. And for worm wheels, they can be roughly divided among cutting the teeth, cutting teeth after casting, and tooth cutting after the outside rim is definitely cast around the guts of the blank.