Worm gears are usually used when large velocity reductions are needed. The decrease ratio is determined by the number of begins of the worm and amount of tooth on the worm gear. But worm gears possess sliding contact which is silent but will produce heat and also have relatively low transmission effectiveness.
As for the materials for production, in general, worm is made of hard metal as the worm gear is manufactured out of relatively soft metal such as 
for example aluminum bronze. This is since the number of teeth on the worm gear is relatively high in comparison to worm with its number of starts being usually 1 to 4, by reducing the worm equipment hardness, the friction on the worm tooth is reduced. Another worm wheel china characteristic of worm manufacturing may be the need of specific machine for gear cutting and tooth grinding of worms. The worm equipment, on the other hand, may be made out of the hobbing machine utilized for spur gears. But due to the various tooth shape, it is not possible to cut a number of gears at once by stacking the apparatus blanks as can be done with spur gears.
The applications for worm gears include equipment boxes, angling pole reels, guitar string tuning pegs, and where a delicate rate adjustment by utilizing a large speed reduction is necessary. When you can rotate the worm equipment by worm, it is normally extremely hard to rotate worm by using the worm gear. This is called the self locking feature. The self locking feature cannot always be assured and another method is recommended for accurate positive reverse prevention.
