Worm gears are often used when large velocity reductions are needed. The 
reduction ratio depends upon the worm wheel number of starts of the worm and quantity of the teeth on the worm equipment. But worm gears have sliding get in touch with which is silent but tends to produce heat and also have relatively low transmission performance.
For the materials for production, in general, worm is made of hard metal while the worm gear is made from relatively soft metal such as for example aluminum bronze. This is because the number of tooth on the worm equipment is relatively high in comparison to worm with its number of begins being usually 1 to 4, by reducing the worm equipment hardness, the friction on the worm the teeth is reduced. Another characteristic of worm manufacturing is the need of specific machine for gear cutting and tooth grinding of worms. The worm equipment, however, may be made with the hobbing machine used for spur gears. But due to the various tooth shape, it isn’t possible to cut many gears at once by stacking the gear blanks as can be carried out with spur gears.
The applications for worm gears include equipment boxes, angling pole reels, guitar string tuning pegs, and in which a delicate swiftness adjustment by utilizing a sizable speed reduction is needed. While you can rotate the worm equipment by worm, it is usually not possible to rotate worm by using the worm gear. That is called the personal locking feature. The self locking feature cannot continually be assured and another method is recommended for true positive reverse prevention.
