Machining synonyms

The toothed wheels give a slightly better efficiency, but the worm gear is somewhat smoother in its action and entirely silent; the noise of gearing can, however, be considerably reduced by careful machining of the teeth, as is now always done, and also by the use of pinions made of rawhide leather or other non-resonant material.

The expense of cutting castings accurately to shape, cutting on them screw threads and what not, called " machining " in trade parlance, is often a very large part of their total cost; and it increases rapidly with the hardness of the metal.

Hence objects which need much machining are made rich in graphite, so that gressively from the state of graphite to that of cementite as we pass they may be cut easily, and those of the latter class rich in from specimen to specimen, may, with the foregoing picture of a cementite so that they may not wear out.

Castings which, like hydraulic press cylinders and steam radiators, must be dense and hence must have but little graphite lest their contents leak through their walls, should not have more than 1.75% of silicon and may have even as little as 1% if impenetrability is so important that softness and consequent ease of machining must be sacrificed to it.