Transcript Training - Plymouth University

Mould tools
John Summerscales
Outline of lecture
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Tool design
Tool materials
Decision matrix
Heating and cooling
Lost cores
Clamping
Ancillary materials and systems
Tool design
•size, complexity and dimensional tolerances
•surface finish
•thermal expansion, conductivity etc
•holes, bosses and ribs
•inserts and fasteners
•re-entrants/multi-part moulds
•number of components to be produced
•durability, ease of modification and
repairability
Tool materials
• Reductive manufacture (CNC machining)
steel
o aluminium
o monolithic graphite
o syntactic foam (hollow microsphere composite)
o
• Additive manufacture
wet lay-up glass reinforced plastics
o prepreg carbon fibre composite
o electroform nickel (EFN)
o
• backing structures
• Plastech MITTM Multiple Insert Tooling
Pre-preg/EFN tooling
• master
• splash tool
• HT male mandrel/bath master
LTM tooling system omits this stage
• Female tool
LTM tooling system omits this stage
• Tool with backing structure
Decision matrix: tooling options
Nicholas Tiffin, "Choosing better tooling",
Advanced Composites Engineering,
Autumn 1988, 18/19.
Note that the following analysis from
Tiffin's paper is specific to a CFRP
structural fairing
P = Priority
R = Rating
V = Value (P*R)
Decision matrix: tooling options
Steel
Al
Wet Lay
Up
Prepreg
EF Nickel
Critical
parameter
P
R
V
R
V
R
V
R
V
R
V
Dimensional
accuracy
10
7
70
6
60
8
80
10
100
8
80
Operating
temperature
10
10
100
10
100
7
70
9
90
10
100
Temperature
uniformity
9
4
36
5
45
7
63
10
90
10
90
Long tool life
8
10
80
9
72
1
8
8
64
8
64
Short cure
cycle
6
3
18
4
24
9
54
9
54
9
54
Tool build
time
6
6
36
6
36
9
54
9
54
5
30
TOTAL
340
337
329
452
418
Tracking
barcodes or RFID inserts
may be attached to mould tools
to permit integration,
e.g. with resin delivery systems,
and automation.
Heating
• fluid in pipes
• embedded electrical heaters
• ovens and autoclaves
Cooling
• fluid in pipes
Embedded heaters 1
• Thermion fabric
• Gorix ECT
• Plastech
cotton/lycra
heater cloth
Embedded heaters 2
• PPM Solutions
• Plastech copper piping
Heating performance
Comparison of cure cycle for 11 mm
laminate on heated tool and in oven.
The two temperature traces in each
case are for the opposed laminate faces
140
o
temperature ( C)
120
100
heated tool
80
oven
60
40
20
0
50
100
150
200
time (min)
250
300
350
400
Simulated temperature distribution
Steady-state temperature distribution
over tool (below) and laminate (above),
for fixed heater temperature of 130°C
Model =
¼ flat tool
(symmetric).
Thermographic monitoring
Infrared camera image of an
electrically-heated tool-plate
showing hot spots due to wrinkled
heater cloth
Thermogram of
electrically-heated mould tool 1
tool face during heat-up showing cool
spots/lines corresponding to the
thermocouple positions/wires and cooler
outline at the resin-rich mould cavity lip
Thermogram of
electrically-heated mould tool 2
• tool face at target temperature of 90°C
showing ~10°C variation across the
component
Thermogram of
electrically-heated mould tool 3
insulated back surface during dwell at 90°C
Thermogram of
electrically-heated mould tool 4
tool back face (GRP side) without insulation
showing the resistive heater element
spacing (horizontal shading)
Lost cores
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rubber/elastomers [Musch and Bishop]
inflatable mandrels [Musch and Bishop]
low melting point alloys [Haines]
candle or paraffin wax
(melting points typically 50-90ºC)
• soluble salts or plaster
(subsequently washed or machined out)
• Plastech SmartCore
(granules enclosed in a shaped vacuum bag)
Clamping
• bolts
o
labour intensive, low pressure
• hydraulic press
o
capital equipment, good alignment
• vacuum
o
inexpensive, limit ~1000 mbar, sealing issues
Ancillary materials and systems
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mould release (coatings and films)
bagging films (1-sided moulds)
breather and bleeder cloths (vacuum bag)
flow media (infusion)
tacky tape - edge dams - breach units
pressure intensifiers
preforming supports
Acknowledgements
• the respective companies for
illustrations of the embedded heaters
• Dr Stephen Grove for
the performance graph and simulation
• Dave Nelson of FLIR Systems Limited for
wrinkled heater cloth thermograms
• Scott Foster of Metrum Information Storage
Limited for skeg thermograms