UWE Bristol Engineering showcase 2015

Travis Chamberlain
MEng Aerospace Engineering Design
Project Supervisor
Dr. David Richardson
DESIGN AND MANUFACTURE OF A COMPOSITE WINGLET’S TOOLING
USING ADDITIVE MANUFACTURING
Introduction
Additive Manufacturing (AM) has been in
existence for thirty years and was primarily used to
create prototypes for products, usually for testing
purposes. Now, the state of the technology means
AM is able to print out fully serviceable parts, with
its main use being for Rapid Prototyping (RP).
Rapid Tooling (RT) is a technique used to bypass
the manually manufactured mould stage, thus
reducing lead times and to allow the manufacture
of composite materials using AM printed moulds.
In recent years, composite materials have even
been printed, but the materials are very expensive
and are an unviable choice for small companies
and hobbyists. Hence the need for RT still exists.
Mould Design
A mould was designed using Solidworks which
came in two main halves: the top and bottom
halves. Because the moulds were too big to print
in UWE’s FDM printer, the top and bottom halves
had to be split in two pieces to be printed
separately and then assembled to form the full
mould.
The mould was designed so that either vacuum
bagging or bladder inflation can be used. The two
halves had self-aligning features to align the four
sections together into one complete female
mould.
Manufacturing
The first few lay-ups were created using the
vacuum bagging technique, but this kept causing
too much resin to be drawn out of the composite,
making it flexible and giving it a poor surface
finish. The lay-up was changed to more natural
method without the use of a vacuum pump. The
resulting winglet halves were of much better
quality, thus this was the preferred lay-up method
for future manufacturing.
The wax used as a release agent was ineffective
because it seeped into small pores on its surface
(created by the FDM printing process). This
rendered the release agent useless. Acetone was
applied to the mould surface to slightly melt its
surface, sealing the pores that plagued previous
lay-ups.
Dry areas were a frequent problem throughout
the manufacturing process. At first, more resin was
added to the composite but for the top mould, this
was due to its complex curvature and not because
of a lack of resin.
Analysis
Both the mould underwent structural analysis
(using FEA) to determine if it could withstand one
atmospheric pressure from the vacuum pump. FEA
was also conducted for the winglet to see if it
could survive a 10 N force acting upon its tip.
Both were shown to endure the maximum
stresses, giving a safety factor 7.5 for the mould
and 1.9 for the winglet.
Maximum
Stress
AM and CNC Cost and Lead Time Comparison
Carbon Fibre Winglet Produced with AM Tooling
Project summary
An investigation has been carried out to determine
the effectiveness of Additive Manufacturing for
producing tooling for a carbon fibre winglet as
apposed to a conventional, automated machined
process. The mould was cheaper and quicker to
manufacture via Additive Manufacturing than the
conventional method of automated machining.
The assembled winglet made from the mould was not
perfect, but was of good enough quality to warrant
its use as a prototype, highlighting the mould’s main
strength in being able to create quick and cheap
composite parts for illustrative purposes.
Project Objectives
1. Design a full-scale winglet mould that can be used
for different lay-up techniques.
2. Structurally analyse the full-scale mould to
determine if it will be suitable for vacuum pump
lay-ups.
3. Manufacture a lightweight, functional full-scale
winglet of a good surface finish.
4. Analyse the full-scale winglet in terms of its
structural properties and the mould’s design and
manufacturing process.
Project Conclusion
1. The winglet was lightweight (with a weight loss of
70.3% over an ABS 430 printout), but did not have
a good surface finish; hence it is not of a
functional quality.
2. In terms of the ABS 430 mould, its low cost, low
lead time, high design flexibility and resilience to
vacuum pump pressure makes it an attractive
alternative to CNC machining.
3. Additionally, the winglet has stayed true to its
aerofoil and demonstrates AM’s potential, such
that a mould from a more accurate FDM printer
may be able to produce higher quality parts.