Powder metallurgy (P/M) techniques have proven successful in displacing many components within the automobile drive train, such as: connecting rods, carriers, main bearing caps, etc. The reason for P/M’s success is its ability to offer the design engineer the required mechanical properties with
reduced component cost.
There are great advantages in dry hobbing, not only for friendliness
toward the environment, but also for increasing productivity and for decreasing manufacturing cost. Dry hobbing, however, often causes failures in hob cutting edges or problems with the surface quality of gear tooth flanks. These difficulties are not present when hobbing with cutting oil. Pinching and crushing of generated chips between the hob cutting edge and the work gear tooth flank is considered a major cause of those problems.
Instances of damage to discontinuous form ground and surface-hardened gears, especially of large scale, have recently increased. This may be attributed partly to a faulty grinding process with negative effects on the surface zones and the surface
properties.