Aerospace & Defense Technology - May 2024 - 12

Aerospace Production:
Overcoming Challenges
in Composite Machining
C
omposite materials play an
important role in aerospace
manufacturing. The light
weight, durability and ability
to create complex shapes from molds
make these materials ideal for frames
and structural components that enable
lighter, more fuel-efficient aircraft.
While composite structures can weigh
up to 20 percent less than their metal
counterparts, these materials can often be
more difficult to machine. The extremely
abrasive nature of carbon fiber reinforced
polymers (CFRPs) will wear down standard
cutting tools more quickly than almost
any other material. A standard carbide
cutting tool may only hold up to cutting
a few feet of CFRPs before its dimensional
stability fails, while in traditional metal
machining that same tool might last 20 to
50 times that before wearing out.
Adding to the challenge, the makeup
of these materials can be very diverse,
with a wide variety of characteristics.
Some composites will be stacked with
different materials, like metals, or
with fibers aligned in different directions;
others will be meshed in a uni12
directional
material. Some composites
are prone to fraying or delaminating,
while others, like polyaryletherketone
(PEAK) materials, are heat-sensitive
and can adhere to cutting tools.
Contending with these variables
can make it tricky to find the best tool
and process for the job. However, there
are a few general tooling strategies
and cutting principles that shops can
apply when machining composites to
improve the efficiency and quality of
their production.
Tougher Tools Go a Long Way
Composites are notorious for wearing
down tools. And when you're machining
large structural components like a fuselage
component or wing box, or drilling
thousands of holes for rivets, frequent
tool changeouts can become a serious
drag on productivity. In these applications,
investing in polycrystalline diamond
(PCD) tools are well worth the cost,
because they'll last 10 to 15 times longer
than a standard tool.
Using PCD tools that can withstand
the abrasive nature of composites offers
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clear advantages in terms of machine
uptime, surface quality and process
security. They maintain their sharpness
longer and provide a cleaner cut
in composite materials, reducing the
risk of fraying or failure that can lead to
scrapped components.
Diamond tools may have a diamond
coating on the surface, applied using
a chemical vapor deposition (CVD)
process, or they can even be made with
diamond veins that are sintered into
the carbide. Veined tools represent a
significant advancement in composite
machining because they allow for cutting
geometries specific to CFRP materials
that are normally not possible.
A good tool provider will run extensive
tests on PCD tools using composite materials
to provide clear data on performance
and life expectancy to help drive more
predictable results. They'll also be able to
extend the life of the tool through reconditioning,
which is an area that has seen
improvement in recent years. Where previously
you could resharpen a PCD tool
two or three times, you can now resharpen
some tools up to 10 times. The cost of
Aerospace & Defense Technology, May 2024
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Aerospace & Defense Technology - May 2024

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