Challenge: Hobbing process mainly applies the traditional integrated cutter of high speed steel (HSS), and it is congenitally deficient in efficiency.

Solution: Indexable cemented carbide cutter provides both high efficiency and low cost.

Cutters are traditionally manufactured by integral steel since modern metal cutting technology was introduced. Indexable cemented carbide cutters bring revolutionary changes after the 1950s. HSS, however, still dominates, particularly in gear generating.

Though improvements have been made, the integrated HSS cutters are restricted by the low efficiency. Regrinding and recoating for the integrated HSS cutters mean much logistics work.

When considering buying hobs, production managers usually need more than one hob. In concrete operations, almost five or ten hobs are needed. One is used for cutting metals, one for regrinding, one for recoating and one for measurement in the cutter room, and others are still on the way of delivery. To simplify the above procedures, only two indexable hobs can fulfill. One is used for operation, the other for pre-regulation, indexing or retooling.

Another problem is cooling liquid, which usually is cutting oil used for abstracting heat. And yet, cemented carbide cutters perform better at higher temperature. And operations without cooling liquid also bring benefits as low cost for purchase, storage and recycle. For manufactures caring about cleaner, healthier and more comfortable working environment, the cooling liquid-free operation is more preferable.

Integrated cemented carbide has longer working life and can apply higher cutting parameters; all these improve the production efficiency directly. Thus obtained production reserve can increase yield as per demands, or decrease yield to save cost when fewer facilities are enough for demands. The latter advantage has a direct effect on the capital expenditure when new cutters are investigated.

It is usually thought that integrated cutters are more accurate than indexable cutters. In fact, only a new HSS hob can fulfill requirements for precision and it may fail if regrinding and recoating cannot be kept. But indexable hobs almost have no effect on precision as long as the clamping system for cutters is qualified; what is needed is to index or change the cutters.

Take CoroMill 176 concept by Sandvik Coromant as an example, the key feature of the concept is the iLock cutter interface. The clamping system consists of cutter, screw bolt and wedge brick. After many practices, one customer gave feedback that the switch time of cutters shortened to seven seconds. For a facility that has more than 100 cutters, the time advantage is significant. A slideway on the supporting device fixes the cutter in the particular position for precision and prevents lateral movement.

This new concept of hobbing process is a kind of macro technological trend that traditional integrated cutters change to more efficient and economical indexable cutters.