Manufacturing Machinery World April 2022

CASE STUDY
MOTORSPORT SUBCONTRACTOR STARTS FINISH-
MACHINING LARGE CARBON FIBRE COMPONENTS
Headquartered in Fontwell, West Sussex and
operating from four sites near the south coast
of England, GTR Composites
(www.gtrcomposites.com) is probably best
known for supplying Formula One teams
with high quality carbon fibre components
and assemblies.
However they are much more than just
motorsport experts, with an ever increasing
reputation for special projects and all things
automotive. The highly specialised
subcontractor has produced lightweight
chassis and other large parts from composite
materials for a long time, but at the beginning
of 2021 it started final-machining them to
tolerances measured in tens of microns.
Introduction of this new service followed
the purchase of a German-built
Zimmermann
FZU400
(https://kingsburyuk.com/machines/zimm
ermann-fzu) 5-axis machining centre,
installed at GTR's Bognor Regis facility at the
end of 2020 by UK sales and service agent
Kingsbury. Having a 4,000 x 3,000 x 1,250
mm working envelope, the portal machine
was selected from a shortlist of three due to
its ability to hold very high accuracy.
For example, a positional tolerance of 50
microns is achieved on features across a full
chassis, while holes and counterbores are
held to within 10 or 20 microns. As the
components being produced are of high
value, GTR adopts a policy of having an
operator permanently in attendance, even
when the FZU400 is running overnight.
Simon Kingdon-Butcher, joint owner
(with John Biddlecombe) of GTR said, “The
investment has allowed us to expand our
business not only in the motorsport sector
but also on special projects and into more
production chassis work for road-going
supercars. We are presently producing 14
chassis for the research and development
phase of such a vehicle.
“The Zimmermann machine stood out in
terms of its rigidity, which translates into the
tight tolerances we are able to hold when
cutting carbon fibre. We’re able to impress
our customers by hitting really tight limits
that our competitors cannot achieve. This
investment has quite literally moved us
ahead of the rest.
“High spindle power - 34 kW continuous
/ 41 kW peak - enables us to rough
aluminium moulds, while spindle speeds up
to 24,000 rpm means their surfaces can be
finish-machined to very high quality using
minimum quantity lubrication.
“MQL also enables us to mill and drill
carbon fibre components containing titanium
or aluminium inserts in the presence of a
specific type of coolant approved by our
customers.”
He added that their other large capacity 5-
axis machining centres are focused on
pattern making and while carbon fibre can be
cut on them, the parts would typically be of
less demanding accuracy than the
Zimmerman FZU400 is capable of delivering,
despite its much larger working envelope.
However, the machine is also used for large
pattern work and he regards the versatility of
the new capacity as an ideal fit for GTR.
The company is no stranger to making big
components in large quantities, having
produced 250 chassis in recent years for the
MoD's Foxhound patrol vehicle. Transition
to final machining of larger structures and
assemblies in carbon fibre, which entails
cutting cycles of up to 60 hours, is therefore
proving seamless for the subcontractor. The
addition of production volumes for
supercars is seeing work for the motorsport
sector, although remaining at a constant
level, fall gradually from 90% of turnover to
probably around two-thirds as the company
expands.
The HSK-A63 spindle head of the thermosymmetrically
designed Zimmermann
FZU400, which is fitted with extraction to
manage the carbon fibre dust, has ± 300-
degree C-axis rotation and an A-axis swivel
of +125 / -95 degrees, resolution being 0.0001
degree. Tools are exchanged automatically
from a 61-station magazine. Acceleration at
up to 3 m/s2 to 60 m/min feed rate in the
linear axes ensures high productivity and
short non-cutting times.
About the subcontractor's relationship
with the machine supplier Kingsbury, Mr
Kingdon-Butcher concluded, “We've had
some horror stories with unreliable machine
tool companies in the past but we made the
right choice this time.
“Kingsbury's local engineering support,
service and parts availability could not be
better. Back-up has been impressive since
they installed a pair of smaller 5-axis
machining centres of a different make a
couple of years ago and it is proving to be so
again.
“They understood the high knowledge
level of the GTR machinists they were
instructing after the Zimmermann was
commissioned and tailored their training to
suit their needs. It was a good all-round
experience.”
A video of Simon Kingdon-Butcher
speaking about the installation of the
Zimmermann FZU400 at GTR Composites
may be viewed at:
https://kingsburyuk.com/video/gtr
www.kingsburyuk.com
32 Manufacturing Machinery World, March 2022