Gear manufacturing without coolant lubrication is getting more and more important. Modern hobbing machines are
designed to cope with dry hobbing. In the last years carbide hobs were prevailing in high-speed hobbing due to their
excellent thermal stability. Today this high performance rate is confronted with rather high tool costs and a critical tool
handling. Powder metallurgical HSS combined with extremely wear resistant coatings on the base of (Ti,Al)N offer now
interesting alternatives for dry hobbing. It is evident that existing conventional hob geometries can be optimized
respecting limiting factors like maximum chip thickness and maximum depth of scallops. The existing machine concepts
with direct driven tool and workpiece axis have sufficient reserves for increasing feeds and speeds in applications of the
future. An analysis of contemporary used hob geometries shows that modifications in no. of gashes and no. of starts can
increase the efficiency of the hobbing process. That means that a larger number of gashes increases the number of teeth in
the shifting zone. Due to this the hob can be used for a longer time. Regarding to the question of increasing cutting speeds
the texture analysis of a gear that was hobbed at a cutting speed of 1000 m/min shows that there is no influence of the
cutting speed on the structure.
AGMA 02FTM6-2002 pdf download
PS:Thank you for your support!
