a special skiving hob. Profilator has a two to three-year lead on the development of this scudding process when compared to other companies.”
Quicker Grinding Times Andreas Mehr, technology development engineer at
Liebherr-Verzahntechnik GmbH (Kempten, Germany), said that his company’s customers are looking to improve their grinding times while maintaining or improving qual- ity. If gears can be ground more efficiently, he noted, “for example with dressable CBN tools,” or if grinding a large module—instead of profile grinding—can be generated, “then these customers will have a big productivity advan- tage over their competition.” In addition, Scott Yoders, vice president of sales at Lieb-
herr’s US operations (Liebherr Gear Technology Inc.; Saline, MI), said that chamfering and deburring systems integrated within gear-hobbing machines “have been expanded upon by Liebherr to include separate parallel-processing stations” for both chamfering and deburring that do not increase total cycle time. As well as using higher-speed machining, carbide hobbing
and honing to increase productivity, Star SU offers a holistic approach to gear making. “Improvements come from the abil- ity to understand machines, tools, applications and services as a completely integrated process,” the company’s Goodfellow said. To that end Star SU offers what it calls “Total Life Cycle Management, which includes resharpening and recoating of precision cutting tools, as well as maintenance services of gear related machinery.”
Is There a Material Difference? While the companies are unanimous in seeing precision
and increased productivity as the drivers of gear making to- day, there is little consensus on what—if any—impact the new generation of transmissions will have on the materials used to make gears. Gleason’s Schaeferling, for instance, does “not see a clear
trend for different steel materials [in gears] because manu- facturers do not want to incur the higher costs of higher alloying.” He added that the size and shape of gears is not undergoing any remarkable changes “and therefore the exist- ing solutions are a good basis” for the future. Schaeferling does, though, see the “constant development of new materials to increase the capabilities of tools for precutting and finish- cutting operations.” As noted above, GMTA’s Knoy sees the need for new mate-
rials for both tools and gears. EMAG’s Loetzner views the issue of gear material much
the same as Gleason’s Shaeferling: many automakers tend to be conservative and would prefer to stick with the tried, true and inexpensive unless faced with a compelling reason to change.
The ‘Gear Factory’ Loetzner believes EMAG has that compelling reason. It is a
multiprocess machining line nicknamed the gear factory. An improved gear material is required because induction harden- ing is incorporated into the inline manufacturing process, allowing for streamlined material flow because the workpiece is not taken out of the workflow. Te gear factory incorporates all essential processes, from
green turning to hobbing, to hardening, hard turning, laser welding and grinding. Te first machine element is known as a pendulum machine with two spindles. Te term pendulum is used because the turret “swings” between the two spindles. A blank is loaded in the first spindle and the turret machines it, Loetzner said, while the second spindle unloads and loads a blank. Once the blank in the first spindle is complete the tur- ret moves in less than a second to the second spindle and ma- chining begins there while the first spindle unloads and then reloads. Loetzner said this is the fastest process for machining in the green stage. “Te chip-to-chip time is below a second,” he said. “Tat is
the initial throughput improvement.” Automation moves the green-turned part to the second
machine element, a traditional hobbing machine. The third stop, Loetzner said, “is the induction hardening and quench unit and then [the workpiece] goes into a hard turn grind process, or a laser welding module, which al- lows you to put on synchronizing gears or other secondary components that are required, and after that you can add another turning unit. So that whole line allows the gear manufacturer to make gears in a very small footprint in a very flexible manner.”
Compact Footprint According to Loetzner, the gear factory takes up just one
third the space of a more traditional process that requires off-line hardening and annealing ovens. “Te process,” he said, “significantly reduces the investment for the gear manufac- turer and is pretty much cycle-time neutral.” While the new process does not directly increase through-
put, said Loetzner, by eliminating the offline hardening steps—removing the gears from the machine tool so the gears can be hardened and then returning them for further machin- ing—the process does remove non-value-added time from the gear making process. “It is,” Loetzner said, “a technology that does require a
change in gear material ... [Tis] does not require a change in the machine tools used or in the machining technique. Tool life is the same. Once the transmission designers catch up to it and design to manufacture with this option in mind, it’s just a matter of time before the gear factory will drive cost savings in manufacturing, through value stream improvement and reduction in floor-space requirements.”
Motorized Vehicle Manufacturing 53
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