Worm gears are usually used when large rate reductions are needed. The decrease ratio is determined by the number of begins of the worm and amount of the teeth on the worm equipment. But worm gears have sliding contact which is noiseless but will produce heat and also have relatively low transmission efficiency.
As for the materials for creation, in general, worm is constructed of hard metal while the worm gear is manufactured out of relatively soft metal such as for example aluminum bronze. That is because the number of tooth on the worm gear is relatively high compared to worm using its number of starts being usually 1 to 4, by reducing the worm gear hardness, the friction on the worm the teeth is reduced. Another characteristic of worm manufacturing is the need of specialized machine for gear trimming and tooth grinding of worms. The worm equipment, on the other hand, may be made out of the hobbing machine used for spur gears. But due to the various tooth shape, it is not possible to cut a number of gears simultaneously by stacking the gear blanks as can be done with spur gears.
The applications for worm gears include equipment boxes, angling pole reels, guitar string worm wheel china tuning pegs, and where a delicate acceleration adjustment by utilizing a big speed reduction is needed. 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.