The manufacturing ways 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 pearly whites, cutting the teeth after casting, and the teeth cutting after the exterior rim is usually cast around the guts of the blank.
As for the materials for worm gears, for worms: structural carbon metal (S45C, etc.), structural alloy metal (SCM415, etc.), stainless and cast iron happen to be employed; and for worm wheels: cast iron (FC200, etc.), non-ferrous metals such as phosphor bronze and specialty bronze (nickel bronze, aluminum bronze, etc.), engineering plastics such as MC Nylon, etc. As the combination of products for worms and worm wheels affects the allowable transmission pressure and lubrication strategies, the decision of mating materials requires careful consideration. Also, linked to the friction of teeth, a harder material for worm than worm wheel is generally used.
Ordinarily the lead angles of the proper and remaining tooth surface of a worm are the same. Yet, in duplex worm gears, they are created so that the tooth thickness of the worm alterations constantly in the axial course so that by shifting the worm axially with shims, it turns into possible to modify the backlash.
If a worm gear is used, a huge speed lowering can be acquired in a compact space in comparison to using spur gears. Generally, the worm is utilized to turn the worm steering wheel. However when the lead angle is particularly small, the worm wheel cannot turn the worm and it is known as its self locking characteristic. This can be utilized effectively in a few applications but it can’t be called excellent preventative for invert driving. (When the lead angle can be large, it is possible to plastic worm gear transform the worm with the worm steering wheel.) In addition, there are many advantages to worm gears such as for example low noise and vibration, but as a result of the large sliding at the tooth areas (sliding contact), the performance is low. (For cylindrical worm gears, the general efficiency is approximately 30-90%.) Also, there are disadvantages such as they tend to suffer from tooth surface high temperature seizure.