Even on the most crowded show floor, it’s hard to miss a massive five-axis machining center with a 344-inch footprint and a 17,000-pound workpiece capacity. But at Innovation Days 2011, the imposing size and reflective sheen of the DMU 210 P duoBLOCK® weren’t its only draws.

 

Attendees at the May DMG / Mori Seiki USA open house in Hoffman Estates, Ill., watched in awe as this beast in a sleek white package took on a nearly 5-foot-diameter, 1045 steel gear in record time, with help from a never-before-seen gear-milling method that can cut cycle times significantly.

 

This is an impressive feat, considering the nature of conventional gear technologies. As one of the last machining processes to be integrated on standard CNC machines, gear milling has traditionally been an arduous process. Despite advancements over the last decade—including enabling hobbing on mill-turn machines and lathes with integral motor turrets—the high cost and limited flexibility of the hobs continued to be problematic.

 

Long setup times, burdensome inventories of specialty tooling, and a general lack of productivity led DMG / Mori Seiki  and its Qualified Products (QP) tooling partner, Sandvik Coromant, to seek a better alternative.

 

The new technique—for which Mori Seiki and Sandvik Coromant have patents pending—allows manufacturers to machine spur gears, helical gears and splines on lathes, mill-turn and five-axis machines in a single setup with multipurpose, off-the-shelf tooling.

 

Dr. Stefan Scherbarth, Applications Center Manager for Sandvik Coromant Germany, spoke about the process—which works on a variety of gear sizes—at Innovation Days. Scherbarth expects that gear makers will have a lot to gain from the process in the near future.

Taking back time

The method, he explains, relies on the ability to better control the tool path, using standard CAD/CAM and post-processing software—and eliminates the need for dedicated and inflexible tooling. Greg Hyatt, VP of Engineering and Chief Technical Officer at DMG / Mori Seiki USA, also spoke on the topic at Innovation Days.

“Typically, hobs and other cutting tools determine the gear profile,” says Hyatt. “In this situation, the gear geometry is the result of the tool path and the machine’s simultaneous milling capabilities. This makes for an easier, faster and more sophisticated gear-milling process.”

 

The method uses a combination of slot milling and turn milling to machine the gear-tooth geometries: slot milling for the gear-tooth bottom land and fillet radius; and turn milling for the involute flank.

 

The new process has generated significant excitement—first internally, and now among customers at Innovation Days—and both companies are working together to further polish the machining, programming and tooling components that enable the process. It’s all thanks to the synergy of the two companies’ core competencies: with Sandvik Coromant providing the method and tooling and DMG / Mori Seiki developing the programming solutions.

 

DMG / Mori Seiki is thrilled to have partnered with Sandvik Coromant in this endeavor, says Hyatt, and relished the opportunity to show it off on two machines at Innovation Days—the DMU 210 P duoBLOCK and the NTX1000.

 

“Many of our U.S. customers have never seen this before now,” says Hyatt. “But it’s already getting a lot of buzz—especially among shops in the energy and aerospace industries—because of how much time and money it can save.”

 

For applications that require very large, time-consuming gear machining, the cost savings could be substantial—particularly when the gear is one of the most expensive components of the finished product. The gearbox of a wind turbine, for example, represents up to 25 percent of its total cost. With wind energy projected to grow by as much as 15 percent each year between 2010 and 2017, it’s easy to see why this substantially more productive gear-milling method has people talking.

 

One of those people is Tom Eul, Production Manager at Cicero, Ill.-based Brad Foote Gear Works, a leading producer of large gearing systems for the energy, steel and transportation industries.

 

“The traditional way of cutting gear teeth is very old, slow and time-consuming,” he says. “This new method decreases cycle time dramatically. Instead of taking days to make a gear, it can do it in hours.”

 

Eul estimates that a gear that might take his shop five or six eight-hour shifts could be finished in a single shift with this method. Speed and productivity enhancements are obviously appealing, and so is the fact that this technique erases the need for specialized tooling and fixtures.

 

“Before, you needed very specific tooling that could only be used in specific gearing applications,” explains Eul. “Now we can use off-the-shelf tooling that we can have at our doorstep within hours—and it’s tooling that can be used in other types of machining.”

 

Eul adds that these advantages represent huge cost savings—despite an initial investment.

 

“Down the road, the machine for this type of gear milling pays for itself ten times over,” he says.

 

Eul also acknowledges the importance of the Sandvik Coromant programming concept.

 

“It’s about the total package—the machine plus the programming,” he says. “When it comes to gear milling, the programming really solidifies it.”

 

Eul says he gelled with the engineers on the Innovation Days floor, who walked him through the machining demo.

 

“This is exactly what I came here to see,” Eul says of his brush with the new gear-milling methods and technology solutions. “I am very, very pleased.”