Heat Pipe Thermally Enhanced (HPTE) Mandrels In Filament Winding Applications New Methodology
Jan 19, 2015
Heat Pipe Thermally
Enhanced (HPTE) Mandrels
In Filament Winding
Applications
New Methodology
Well Established in
Automotive Tooling
1
Heat pipes
What value does heatpipe technology bring to mandrel design and
filament winding process optimization?
1
Heat pipes
Heatpipe Operating Principles
2
Heatpipes transfer large amounts of thermal energy rapidly.
Heatpipes are intrinsically Isothermal.
Heatpipes redistribute localized energy inputs.
Heatpipes have an Intuitive, remediating response to locally
generated energy deficit and surplus transients. (sinks and
exotherms)
Heatpipes require no electrical power or mechanical
connections.
Heatpipes are sealed systems.
Heatpipe Features & Benefits
4
HPTE Mandrels
3
“In Oven” Convection
Oven Curing of
Filament Wound Tube
Sections
The cure sequence usually occurs in a heated
convection oven or radiant energy environment.
Energy is provided to the surface of the
resin/filament composite through the heated
oven atmosphere at low watt density.
A large percentage of energy produced by the
oven is vented and not efficiently utilized.
Current “In Oven” Cure Challenges and Limitations
3
The mandrel is not directly heated.
The mandrel is the last component to be heated.
The cure is initiated at the outside surface of the
winding, sealing the outer surface of the tube
section, trapping gasses and vapour liberated during
the cure cycle.
Trapped gasses and vapours contribute to
delamination and porosity.
Current “In Oven" Filament Winding Cure Challenges and Limitations
3
HPTE Mandrel Testing Cell
5
Traditional Mandrel Test Results
Transient Temperature Curves for the Hollow Mandrel
0
20
40
60
80
100
120
140
0 5 10 15 20 25 30 35 40 45
Time (Min.)
Su
rface T
em
p.
(deg
.F)
Top (2")
Mid (33")
Bottom(60")
Delta T (bottom-top)
Date: Jan. 9, 09
Sand Bath Temp. 350 Deg. F
Heat Transfer Rate: ~12W.
Mandrel OD. 1.875".
Mandrel Length: 72".
TC location is the distance from the top.
6
Transient Temperature Curves for the Mandrel-Isobar
-20
0
20
40
60
80
100
120
140
160
180
200
220
240
260
0 10 20 30 40 50 60 70 80 90 100
Time (Min.)
Su
rface T
em
pera
ture
(d
eg
. F
)
Top (2")
Mid (33")
Bottom (62")
Delta T (bottom-top)
Date: Jan. 8, 09
Sand Bath Temp. 350 Deg. F
Heat Transfer Rate: ~210W.
Mandrel OD. 2".
Mandrel Length: 74".
TC location is the distance from the top.
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HPTE Mandrel Test Results
Exposed surfaces of the HPTE mandrel absorb thermal energy
from the oven and transfer it directly to the mandrel.
This absorbed thermal energy is immediately redistributed
throughout the HPTE mandrel.
The redistributed thermal energy results in a dynamically
isothermal mandrel.
The heated isothermal mandrel provides an optimum uniform
cure platform providing thermal energy from I.D. to O.D. of the
tube section.
HPTE mandrels thermodynamic features in conventional oven curing applications
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The mandrel is now thermally uniform. (isothermal) and super
thermally conductive and reactive to the ambient temperatures
within the oven.
Resident energy within the oven is absorbed through the
exposed ends of the mandrel, heating the mandrel directly and
efficiently.
Because both the I.D. and O.D. surfaces of the winding are now
actively heated, the cure cycle time is reduced.
The heated mandrel draws resin to the I.D. of the winding
resulting in a tube section with a homogeneous, resin rich,
nonporous surface on the tube inner diameter.
HPTE mandrels in convection oven curing applicationsthermodynamic benefits
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HPTE Mandrels
3
“Out of Oven”
Induction Curing of
Filament Wound Tube
Sections After
Winding
Induction cure sequence using a HPTE Mandrel winding and curing a 3” I.D.
Tube section with ½” wall using carbon fiber epoxy prepreg
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The induction heating coil is situated proximate to the
mandrel permitting unimpeded mandrel rotation.
Induction heating is relatively instantaneous and intense.
RF energy is invisible to the uncured resin and filament
but fully sensed by the metal mandrel.
Significant thermal energy per unit time can be provided
to the mandrel which then intimately transfers that energy
to the uncured composite resulting in significant energy
efficiencies.
HPTE mandrels in induction
heated “out of oven”curing applications
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Testing Cell for Induction heating of both a HPTE Mandrel
and a Traditional Mandrel
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3” Standard hollow mandrel: Thermographic study with induction heat
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187.70 ºF
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3” HTPE mandrel: Thermographic
study with induction heat
183.02 ºF
Traditional hollow mandrel vs. HTPE mandrel
64” X 3” rotating at 100 RPM and heated by an
induction coil providing 850 Watts
Time lapse video sequences
HPTE Mandrels
3
“Out of Oven”
Induction Curing of
Filament Wound Tube
Sections While
Winding
Video of a cure while winding sequence using a HPTE Mandrel winding and curing
a 3” I.D. tube section wound of carbon fiber epoxy prepreg
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The mandrel now provides the uncured composite with
100% of the thermal energy requirement. The cure begins
at the mandrel surface and continues through to the tube
section outside diameter.
Curing from the inside diameter to the outside surface
allows volatile vapours generated during the cure
sequence to be liberated to atmosphere reducing porosity.
Resin is drawn to the hottest surface during the cure
resulting in a resin rich non porous I.D.
HPTE mandrels in induction
heated “out of oven” curing applications
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SAMPLE A Induction Cure vs. SAMPLE B Oven Cure
CT Scan Defect Analysis
A: Induction Cure
Marker
B: Oven Cure
A: Induction Cure
B: Oven Cure
Sample A: Induction Cure
Volume: 1288.8789 mm3
Defects: 2.7777 mm3
Porosity: 0.21505 %
Defect Volume Distribution vs. Defect Count
Sample B: Oven Cure
Volume: 1452.3339 mm3
Defects: 2.7764 mm3
Porosity: 0.19080 %
Defect Volume Distribution vs. Defect Count
Sample A: Induction Cure
Sample B: Oven Cure
Defect Volume Distribution vs. Defect Count
Volume: 1288.8789 mm3
Defects: 2.7777 mm3
Porosity: 0.21505 %
Volume: 1452.3339 mm3
Defects: 2.7764 mm3
Porosity: 0.19080 %
Ameritherm Div of Ambrel Corp, Springfield NY Induction power supply and coil
Chino Works America, Chicago Illinois Infrared sensor and process controller
McClean Anderson, Schofield Wisconsin Filament winding machine and laboratory
TCR Composites, Ogden Utah Prepreg epoxy filament materials
Acrolab Ltd, Windsor Ontario, CanadaHPTE mandrel
Technology providers for this project
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Joseph Ouellette
Director, Advanced Research
& Development
Acrolab Ltd.
Thank you
Advanced Thermal Engineering /Research and Development
Windsor, Ontario, CANADA
www.acrolab.com