JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 37

AERONAUTICS
tooling

Stack drilling with diamond tool materials

mattheW goulbourn-lay,
Senior Advanced Manufacturing
Research Engineer
Element Six

iamond tooling has proven to
be highly successful in drilling
CFRP due to its extreme properties such as high hardness, abrasion
resistance and thermal stability. There
has previously been a gap between the
ability to produce the complex cutting
geometries required for extreme applications and the shapes of formats
available in solid diamond materials.
Attempts to bridge this gap using
Diamond-like Carbon Coating (DLC)
and Chemical Vapour Deposition
(CVD) diamond coating of tungsten
carbide (WC) tool geometries have
been partially successful. However, the
unpredictable chipping performance of
coatings leads to variable performance
and tool life. Combined with the high
economic cost of re-sharpening, this

makes coatings less desirable as a tool
material than solid diamond in the form
of PCD (Polycrystalline Diamond).
Recent advancements of 3D PCD
formats such as Element Six's AeroDianamics™ range, coupled with stateof-the-art tool processing methods
such as Electro-Discharge Machining/
Grinding (EDG) and laser processing,
have brought PCD to the forefront of
cutting tool technology for extreme
applications.
CFRP, titanium and aluminium
So why is a multi-material stack so difficult to machine, even with such an extreme tool material like diamond? The
three most common materials utilised
in stacks are CFRP, titanium (Ti) and
aluminium (Al), with configurations
such as CFRP/Ti, CFRP/Al or Ti/
CFRP/Al. CFRP alone is very difficult
to machine due to its anisotropic and

non-homogeneous structure combined with highly abrasive reinforcing
constituents. Added to this, the resin
matrix material typically has a very
low temperature resistance. Once the
resin's critical temperature is reached,
permanent damage occurs which
increases quality issues such as delamination, fibre breakout and uncut fibres.
Controlling process parameters such as
cutting speed and feed rate is critical
in order to control the temperature
generated during cutting, while maintaining a sharp cutting edge enables
more effective cutting of each fibre by
brittle fracture. In comparison, aluminium presents a much easier material to
machine, by ductile shearing and little
abrasive wear results. However, issues
such as chip control, built-up edge and
exit burr formation can be difficult
issues to control when the tool begins
to wear. In contrast to aluminium, titanium is typically extremely difficult to
machine due to its low thermal conductivity and high chemical affinity. These
cause excessive adhesion of Ti material
to the cutting edge, which causes a
plucking phenomenon and eventually
premature tool failure. Titanium's low

Feature Aeronautics

D

The aerospace industry has pioneered the use of carbon fibre reinforced
polymers (CFRP) for numerous years, in many shapes, sizes and types. For
applications where CFRP alone might fail, further materials such as aluminium and/or titanium are combined to make a multi-material stack. In a
safety-conscious industry, mechanical fastening is the method of choice for
joining components. This results in the requirement to produce many thousands of holes per aircraft. Hole production to tight tolerances, typically H8,
and high economic efficiency requirements mean CFRP alone is a significant
challenge. When adding dissimilar materials in a stack format, hole production
becomes highly problematic.

/ jec composites magazine

37

No112 April - May 2017



Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017

Cover
Edito
Opinion: Civilian robotic
Contents
NEWS
In brief
Yachting
Strategy
Fabric
Agenda
BUSINESS
Additive manufacturing
Carbon
MANUFACTURING
Press
Repair
CNC
Natural fibres
Feature Aeronautics - Will the horizon stay clear?
Simulation
Software
NDT
Tooling
Self healing
Primary structure
Natural fibre
Recycling
Environment
Structures
SOLUTIONS
Sustainability
Sailplane
Lift
Construction
In the world
TECHNOLOGY
Nanomaterials
Thermoplastics
CFRP
Index
Advertisers
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 68
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Cover
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 2
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Edito
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Opinion: Civilian robotic
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 5
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Contents
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 7
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - In brief
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 9
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Yachting
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 11
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Strategy
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 13
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Fabric
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 15
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Agenda
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 17
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Ad IPC
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Ad JEC
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Additive manufacturing
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 19
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Carbon
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 21
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 22
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Press
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 24
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Repair
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - CNC
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 27
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Natural fibres
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 29
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 30
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Simulation
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 32
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Software
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 34
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - NDT
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 36
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Tooling
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 38
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 39
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 40
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Self healing
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 42
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Primary structure
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 44
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Natural fibre
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 46
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 47
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Recycling
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 49
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Environment
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Structures
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 52
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 53
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Sustainability
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Sailplane
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Lift
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Construction
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - In the world
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Nanomaterials
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 60
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 61
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Thermoplastics
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 63
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - CFRP
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 65
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - Advertisers
JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 67
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