Machining of Worms

Machining of Worms

Machining of Worms - Various types of worms can be machined by

(i) Milling,
(ii) Robbing,
(iii) Shaping.

Each milling cutter is specially designed for cutting a specific worm. For volume production, a multiple thread cutter is set with its axis parallel to the work axis and is fed to depth. The work then makes one revolution for completion.Hobbing produces on mass, highestgrade worms or the lowest machining cost.

Because of the large helix angle at which most worm hobs operate, the teeth at the entering end are chamfered to reduce the cutting load. The number of flutes in a worm hob may be increased to improve surface finish, because greater the number of flutes, the smaller the feed marks.

Worms can be cut by a shaper cutter also. A helical gear cutter is used for the purpose, Both the work and the cutter rotate and, in addition the cutter is rolled axially along the worm, providing true generating action.