Between pricing pressure from automakers and other gear users and increasingly stringent quality standards, eliminating steps in the production process is critical to reduce manpower needs and eliminate manual processes where error can enter production.
German workholding specialists Hainbuch developed the Mando G211 mandrel to eliminate reworking steps for gear manufacturers, working with gear producer Hänel to test and develop the system.
“With the current clamping system, we didn’t achieve a good concentricity. The workpiece was pressed axially downwards,” says Jürgen Renner, production manager at Hänel, also in Germany. “Now, it’s clamped with the mandrel from the inside, radially outwards. We have higher stability within the clamping, eliminating reworking of certain components. For some of our orders, the old clamping system was good, because the concentricity was not as important. But the better the concentricity, the easier it works later. With a normal hardened gear, the bore still needs to be reworked, but all the workpieces that are fully geared can now be reduced to one operation.”
Hainbuch initially sent Hänel two prototypes of the Mando G211 mandrel, sizes zero and two, for testing on a Richardson R 400 manual loading machine and a Gleason-Pfauter GP 200 hobbing machine with automatic loading.
“For our employees, this new clamping system was very strange. For 20 years, they worked with a clamping system from the machine manufacturer without radial clamping, which has worked fine so far,” Renner explains. “For the first attempts, we had to make some adjustments to the machine. In addition, we did not reach our zero line on the Gleasen-Pfauter machine because the mandrel was too tall. As a result, adjustments to the machine and loading system were required.”
Hainbuch product manager Thomas Steiger and designer Hannes Ludwig took Hänel’s feedback and adapted the mandrel. Second-generation prototypes were stiffer and thinner, better suited for Hänel’s machines.
While reducing rework was the chief goal, Renner says Hänel also hoped to reduce setup times.
The mandrel allows Hänel to consolidate smaller orders if the components are similar. With the Mando G211 mandrel, only the segmented clamping bushing needs to be changed during setup, not the entire clamping system, eliminating time-consuming alignment operations. The system uses three screws on the mandrel and one on the segmented clamping bushing, reducing the number of items to be adjusted when changeovers are needed.
“If everything is prepared, optimally the part family is in stock and can be processed one after the other; we will certainly save 50% of the set-up time,” Renner says. “Not only is the setup faster, the process is safer and more stable.”
Higher stability allows higher feed rates, while lower vibration from the mandrel extends tool life, says Andreas Hoffmann, Hänel’s head of toolmaking.
Hänel now has six Mando G211 mandrels: the two prototypes and four standard mandrels in sizes zero to four.
Hoffmann explains, “All new components have been manufactured with the mandrel ever since. Even with older components, we try to change over to the mandrel clamping, because the segmented clamping bushings from Hainbuch can be delivered within one day. That’s a huge advantage for us.”