WORKHOLDING CHUCKING OUT INEFFICIENCY
In just one minute, the entire Schunk clamping pyramid can be
exchanged to a repeat accuracy of 0.005 mm
“I don’t need to tighten any screws, or
look for any washers or keys,” says Maas.
“All clamping devices are precisely and fi rmly
connected to the machine. The clamping
result is always identical, without anything
having to be aligned. And the fl exibility is
Radially arranged clamping slides retract
and self-lock the clamping pin with the Vero-S
via a spring assembly that uses form-fi t
clamping. Clamping and positioning is carried
out via a short taper, which ensures a repeat
accuracy of <0.005 mm. Due to the patented
dual-stroke system, each module achieves
pull-down forces of 7.5 kN. With activated
turbo-function, the pull-down force is 25 kN,
while the retention force is 50 kN.
Maas makes particular use of the
clamping pyramids from the more than 1,000
variants of the modular Vero-S system: “With
the pyramid, it is irrelevant whether I machine
four identical parts in series or four individual
components, because I can bundle similar
parts together on the pyramid at any time.
My vision is to have four different zero points
on the pyramid one day, and to be able to
machine completely different components.”
The Vero-S clamping pyramids are
combined with manually actuated Schunk
Kontec KSC 125 clamping force blocks, in
lengths of 160 and 300 mm.
“With comparably low torques, I can
achieve high clamping forces of 35 kN,
meaning I can completely do without a
separate stamping station for form-fi t
clamping,” says Maas.
As clamping takes place under tension,
the bending load on the base body and,
thereby, the lifting up of the clamping vice,
are minimised, which adds to clamping
accuracy and rigidity. A pre-tensioned centre
bearing (without spindle reverse clearance)
and specially adjusted slides ensure a repeat
accuracy of ±0.015 mm.
Remaining in Germany, recent teamwork
between gear manufacturer Hänel and
workholding specialist Hainbuch (https://
is.gd/buzoru) has certainly paid dividends.
The Hainbuch Mando G211 mandrel for gear
manufacturers is particularly suitable for gear
hobbing, cutting and grinding, a fact ably
demonstrated at Bad Friedrichshall-based
Hänel. Now available as a standard mandrel
from stock, this solution for gear cutting has
optimised Hänel’s manufacturing process,
reduced set-up times and improved gear
quality, largely credit to the stable clamping
features that dampen vibration.
When a product like the Mando G211
mandrel is fi rst developed, it must be tested
thoroughly under real-world conditions. In this
case, Hainbuch was looking for a reliable
partner capable of testing the prototype, and
so the company approached Hänel.
Hänel initially received two Mando G211
mandrel prototypes in sizes zero and two. The
mandrels were tested on a Richardon R400
manual loading hobbing machine and a
Gleason-Pfauter GP200 gear hobber with
automatic loading, to see if they would be
At Hänel, batch sizes are between 30 and
1,000 pieces. As a rule, the gears are
hardened and ground, so reworking is not an
option. “With the current clamping system we
couldn‘t achieve good concentricity,” admits
Jürgen Renner, production manager at Hänel.
“The workpiece was pressed axially
downwards. Now it is clamped with the
mandrel from the inside, radially outwards.
Thus, we have higher clamping stability. This
eliminates the reworking of certain
Hänel has also improved set-up times with
the new mandrel, as when using the Mando
G211 mandrel only the segmented clamping
bushing, and not the entire clamping system,
has to be changed. Use of the G211 also
eliminates the need for alignment, which of
course saves time. Even if the mandrel and
segmented clamping bushing have to be
changed to a different size, it is still faster.
There are only three screws on the mandrel
for the support and one screw on the
segmented clamping bushing.
“If everything is prepared optimally, and
the part family is in stock and can be
processed one after the other, we will save
50% on set-up time,” concludes Renner.
“In addition, the process is more stable and
The Mando G211 mandrel on the
Richardon is perfect for hobbing
52 November 2018 www.machinery.co.uk @MachineryTweets