The manufacturing methods of worms are roughly divided among cutting, heat treated and ground after plastic worm gear cutting and rolling. And for worm wheels, they may be roughly divided among cutting teeth, cutting pearly whites after casting, and the teeth cutting after the outside rim can be cast around the guts of the blank.
As for the elements for worm gears, for worms: structural carbon steel (S45C, etc.), structural alloy metal (SCM415, etc.), stainless and cast iron are applied; and for worm 
tires: cast iron (FC200, etc.), nonferrous metals such as phosphor bronze and specialty bronze (nickel bronze, metal bronze, etc.), engineering plastics such as MC Nylon, etc. As the combination of materials for worms and worm wheels affects the allowable transmission push and lubrication methods, the choice of mating resources requires careful consideration. Also, related to the friction of tooth, a harder materials for worm than worm steering wheel is generally used.
Ordinarily the business lead angles of the proper and remaining tooth surface of a worm are the same. Yet, in duplex worm gears, they are made so that the tooth thickness of the worm alterations continuously in the axial way so that by shifting the worm axially with shims, it becomes possible to adapt the backlash.
If a worm gear is used, a big speed reduction can be acquired in a compact space in comparison to using spur gears. Generally, the worm is used to carefully turn the worm wheel. However when the lead angle is especially small, the worm steering wheel can not turn the worm in fact it is known as its self locking feature. This can be used effectively in a few applications but it can not be called perfect preventative for reverse driving. (When the business lead angle is usually large, it is possible to turn the worm with the worm steering wheel.) In addition, there are many benefits to worm gears such as low noise and vibration, but as a result of the large sliding at the tooth floors (sliding contact), the efficiency can be low. (For cylindrical worm gears, the general efficiency is about 30-90%.) Also, there are down sides such as they tend to have problems with tooth surface warmth seizure.