FOR AUTO RTM

Mubea Carbo Tech
NEWS
FIG. 3 Prepress staging for preforms
MCT Žebrák’s LP-RTM area contains six presses and accompanying mix/meter/
dispense units, which process dry fiber preforms up to 10 mm thick.
chambers. Some of this group’s innovations include zero-point
mounting systems for CNC machining and robotic operations,
precision machining of fine contours and radius-free edges with
minimized thermal stress, contact-free processing of materials to
prevent skew and distortion, and temperature-controlled CNCrobot
bonding to guarantee repeatable joining accuracy.
At MCT, design engineering is the beginning of all parts
production. “We start with drawings from the customer and then
work together to adapt and modify the design and manufacturing,
optimizing for composites,” says Karas. “We design and
develop all of our tooling in house,” adds Siegmann. “The more
you can put in the tool, the more added value you can get out of
the tool and the more competitive you can be,” he explains, “but
this is not easy.”
The tour next moves to a 400m 2 building dedicated to part
production for Volkswagen’s (Wolfsburg, Germany) XL1 dieselelectric
hybrid, designed to travel 100 km on 1L of fuel. MCT
makes a total of 85 parts per car, including the structural tub and
all exterior Class A body components. The building also houses a
third autoclave. The limited production of 250 XL1 vehicles began
in 2013 and finished this year. The building will now transition to
new production work that is in the final engineering stages.
The next building is the largest, covers 600m 2 , and houses the
HP-RTM machine and the prepreg press. “Everyone is talking
about HP-RTM,” Siegmann observes, “but prepreg pressing is
very good technology, especially with thin laminates. Resin saturation
can be an issue with visible carbon parts and there is also
a tolerance issue with thin laminates in RTM.” He explains that
with prepreg, “the resin is already there where you need it, and
pressing can produce 40 visible-surface carbon parts per day per
tool.” Further, the prepreg press can cure up to 10 layers without
the need to debulk.
FIG. 4 Prepreg press for carbon fiber seats
MCT Žebrák uses a prepreg press to make visually stunning seats for
Porsche, which also feature robotically applied, post-cured epoxy adhesive
to attach highly loaded air bag holders.
The final production area on the tour of Building 3 is
the section that houses the HP-RTM machine (see the Side Story
titled “HP-RTM: A means, not an end” on p. 57).
P1/MP4 automated precision
Building 3 also houses the automated manufacturing line and
adjacent, enclosed laser machining cell for the McLaren P1 and
MP4/650S MonoCells (passenger cells or “tubs”). Additional
enclosed CNC milling and waterjet machining centers are located
at the opposite end of the building. According to Siegmann, the
70-kg MP4/650S monocoque is MCT’s most complicated part to
date. The carbon fiber composite tub — which measures roughly
2m by 1.8m by 1m in height — features hollow frames made using
an inflatable core and is molded in one shot using a patented lowpressure
RTM (LP-RTM) process.
CompositesWorld.com
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