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 quantity of tooth on the worm equipment. But worm gears possess sliding contact which is calm but will produce heat and also have relatively low transmission performance.
For the materials for production, in general, worm is constructed of hard metal while the worm gear is made from relatively soft steel such as for example aluminum bronze. That is because the number of teeth on the worm gear is relatively high compared to worm with its number of starts being generally 1 to 4, by reducing the worm gear hardness, the friction on the worm tooth is reduced. Another feature of worm manufacturing may be the need of specialized machine for gear trimming and tooth grinding of worms. The worm gear, on the other hand, may be made out of the hobbing machine utilized for spur gears. But due to the different tooth shape, it is not possible to cut several gears simultaneously by stacking the gear blanks as can be done with spur gears.
The applications for worm gears include gear boxes, angling pole reels, guitar worm wheel china string tuning pegs, and where a delicate rate adjustment by utilizing a large speed reduction is necessary. While you can rotate the worm equipment by worm, it is normally not possible to rotate worm utilizing the worm gear. This is called the self locking feature. The self locking feature cannot always be assured and another method is recommended for true positive reverse prevention.