Worm gears are often used when large speed reductions are needed. The reduction ratio depends upon the number of begins of the worm and quantity of teeth on the worm gear. But worm gears have sliding contact which is peaceful but tends to produce heat and also have relatively low transmission efficiency.
For the materials for creation, in general, worm is constructed of hard metal 
while the worm gear is made from relatively soft metallic such as aluminum bronze. That is since the number of the teeth on the worm equipment is relatively high compared to worm with its number of begins being usually 1 to 4, by reducing the worm gear hardness, the friction on the worm tooth is reduced. Another feature of worm manufacturing is the need of worm wheel china specialized 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 because of the various tooth shape, it is not possible to cut several gears at once by stacking the apparatus blanks as can be done with spur gears.
The applications for worm gears include gear boxes, fishing pole reels, guitar string tuning pegs, and in which a delicate acceleration adjustment by utilizing a sizable speed reduction is needed. When you can rotate the worm equipment by worm, it is generally extremely hard to rotate worm by using the worm gear. This is called the personal locking feature. The self locking feature cannot continually be assured and another method is recommended for true positive reverse prevention.
