Metal Rolling Improves Jig Manufacture
For RTM Carbon Aero Parts
reating manufacturing
jigs for the production of
aerospace components
requires high quality
materials and precision
machining. So, when parts of an original
jig, which had been press-formed,
started to crack, it was essential to find
an alternative production method, which
led to Barnshaws Metal Bending being
contracted to manufacture the new
components.
C
The aerospace industry is understandably
extremely demanding when it comes
to precision and quality throughout the
entire supply chain - in order to ensure
the highest levels of safety. The start of
the manufacturing process for many
components is the production jig, which
has taken on a greater prominence with
the growing application of resin transfer
moulding (RTM) process, which is capable
of producing complex three-dimensional
components using carbon fibre as the
structural element.
Aim Engineering is a specialist
manufacturer of bespoke production
tooling for a variety of industrial sectors
including aerospace and it had been
contracted to produce an aluminium jig
for creating fan cowl components for a
turbofan engine. The base for the moulds
is a set of thick, curved aluminium plates
that would normally have to be machined
from billet to produce the exact shapes
required for the carbon composite
components, however this results in high
waste and cost.
Mark Adams, Production Planner for
Aim Engineering, explains: "Initially the
alternative was to create the curved
aluminium from flat stock using a pressing
process, but this was not ideal as we had
a plate crack during testing and there
were excessive tooling marks on the outer
surface. This led us to look for another
manufacturing method that would
improve the overall quality of the design."
As a regular client of Barnshaws, Aim
Engineering already appreciated the
technical abilities of the metal rolling
company but was a little uncertain
about the feasibility of producing these
jig components using rollers. However,
once the designers had discussed the
requirements it was clear that, given the
correct materials, Barnshaws would be
able to deliver the required components.
The RTM process enables the cost effective
production of precision components from
carbon fibre materials as it requires less
manufacturing time than more t raditional
methods using an autoclave. RTM uses a
vacuum to draw the resin into the carbon
fibres and ensure that all the air bubbles
are expelled before the resin cures.
In order for the process to be robust
and reliable, the production jig must be
strong enough to withstand the repeated
application of pressurised resin and the
vacuum system. In addition, the mould
must be precision machined with an
excellent surface finish as this determines
the quality of the final components.
In all, Barnshaws produced ten rolled
aluminium sections, up to 800 mm in
length and varying in thickness from 83
mm to 114 mm. The level of precision
required for the curvature of each section
was required to hundredths of a degree,
with eight different radii specified for the
sections ranging from 101.09° to 212.40°.
To achieve such precision and tight
curvature, Barnshaws recommended the
use of high quality aluminium 5083 that
had been annealed to reduce the risk of
cracking. This was then passed through
precision controlled rollers to gradually
bend the flat aluminium stock until the
final dimensions were achieved.
Wayne Sakeld, General Manager
at Barnshaws’ Manchester branch,
commented: “We are always looking to
improve existing technologies - applying
our knowledge and expertise to toolmaking for the aerospace sector has
really paid dividends in this case. The
new manufacturing jigs will have greater
durability and improved surface finish,
which makes them more cost effective to
manufacture and use.”
Once the new precision-curved aluminium
components were delivered to Aim
Engineering they were machined to suit a
number of components for the turbofan
engine. The superior quality of the thick
aluminium segments produced by the
rolling process ensured that there was
now no scrappage either of the tooling
components or of the aircraft production
parts.
www.barnshaws.com
Issue 18 PECM
65