technoform applications
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Technoform – For Rapid, Repeatable Thermoformability Analyses
Dr. Amit DhariaTransmit Technology Group, LLC, TXwww.transmit-technology.com
Outline® Properties –Thermoforming Process
relationship ® Current test methods ® Description of Technoform ® Application and data interpretation® Products – Basic, Standard, Advanced® Conclusion
Thermoforming Process®Extruding sheet stock ®Heating sheet above Tg®Stretching heated sheet in rubbery state®Cooling®Trimming ®Finishing
Structure - Properties -Thermoformability® Rate of change of strength with the
change in strain rate at forming temperature
®% Crystallinity – Breadth of rubbery Plateau
® Molecular weight, Molecular weight distribution, molecular architecture (branching, crosslinking) – MFR, Melt Elasticity
Other parameters® Density - % filler, type of fillers, degassing® Geometry – Thickness, area, multi-layered
structures, adhesion between layers® Residual stresses between and within in
extruded layer sheet stock® Thermal diffusivity (Cp, K. Rho)® Extrusion quality ( gels, unmelts,
thickness variation, grain patterns)® Color (IR absorption)
Current tests®Low shear melt viscosity (MFR, RMS)®Melt Tension (Draw Force –Melt
tension, Break Velocity -extension)®Sag Test (sag distance, sag time)®Hot Creep Test®DMA (Relaxation time)
Major disadvantages of current methods® Most tests are conducted in melt or near melt
phase ® Test Specimens does not reflect actual test
geometry (shape, size, clamping mode)® Tests does not account for orientation, thermal
stresses, thickness variations® Isothermal environment, does not account for
transient nature of heating/ cooling ® Effects of secondary process parameters can not
be evaluated® Results cannot be directly used.
What processors want to know?® Will this material thermoform? ® Will this new material process the same? ® Will this lot process the same as the last one?® Why this lot does not process the same?® How much time is needed to heat the sheet?® How fast material will heat?® What is the right forming temperature range?® Will melt adhesion between layers survive
heating and stretching step?® Will material discolor, fed or degrade during
heating?
What processors want to know? -II®What is the maximum draw down?® How fast part can be made? ®What is the MD and TD shrinkage?®Will material tear at the corners and ribs?® How much regrind can I use?®Will grains retain shape and depth?® Does extruded sheet have gels or
unmelts?
What Industry Needs?® A standard test method which reflects all unit
steps – heating, 3D stretching, forming, and cooling
® A test equipment which can be precisely controlled, is rapid, easy to use, provides repeatable and quantitative information, using the lease amount of material.
® Easy to use “Thermoformability Index” standard for comparing, contrasting effects of selected process/ material variables
TECHNOFORM TM
Patent PendingTTG
TECHNOFORM
Schematics of Technoform
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Typical Data input® Mode of operation – Plug Assisted, Vacuum® The heating element distance from the sheet
surface® The heating element temperature® The sheet temperature® Heat Soak time at given temperature® Plug velocity (2 to 200 mm/second)® Plug Delay Time ® Plug Temperature® Part Cooling time
Typical user Input Screen
Sag Distance
Thinning
Strainhardening
Forming Depth mm
Thermoformability Index=slope
Typical Data Output® Heating rate (Delta C/ time) = f (thickness)® Sag distance ® Forming force (Stress) vs. forming
distance (strain)® Forming Force vs. time® Yield force® Forming force vs. actual temperature® Shrinkage (manual measurements)
Effect of Heating time Force vs. Depth (180 C, Isothermal)4" dia hemi-spherical plug, 20 ipm
(effect of pre-heat time)
01020304050
0 20 40 60Depth, mm
Forc
e, lb
s
10 min15 min
Plug Material and Shapes®Truncated cone with flat end (2.5” Top
D, 0.75 “ Bottom D, 4” Height)®Truncated cone with Rounded End (2.5”
Top D, 1” D bottom, 4” Height)®Hemisphere of 3.5” Diameter®All tools made of Foam Epoxy
Effect of Plug Temperature35 Mil Black HIPS, 130 C,40 mm/s
- No control -
0
2
4
6
8
10
12
0 50 100 150
Draw Depth, mm
Forc
e, L
bf Series1Series2Series3
Effect of controlling Plug TemperatureHIPS, 40 mm/second with T control
HIPS @130 C, 40 mm/secondPlug cooled for five minutes
0
2
4
6
8
10
12
0 20 40 60 80 100 120
Depth, mm
Forc
e, L
bf
#1#2#3#4
Effect of Plug GeometryForce vs. Depth 180 C, 40 mm/s
Hemi-Spherical Plug with 4 " Diameter
05
101520253035
0 10 20 30 40 50
Depth mm
Forc
e, lb
s\f
12
Effect of plug materialHIPS, 170 C, 40 mm/second, 35 mil
0
1
2
3
4
5
6
0 20 40 60 80 100 120
Depth (mm)
Forc
e (lb
)
WF WFT Bix
Effect of forming Speed on HDPE @ 150 C
Effect of Forming Speed on HDPE
0
2
4
6
8
10
0 50 100 150Distance (mm)
From
ing
forc
e (N
)
20 mm/sec30 mm.sec50 mm/sec
Heating rates for various plastic materials(Heater at 600 C, 3” from upper, 2” from lower)
30
80
130
180
230
0 20 40 60 80
t (seconds)
T (c
)PPHDPEHIPSPVCABSAcetalPMMANylon
Effect of Crystallinity
05
1015202530
50 70 90 110 130
Forming distance, mm
Forc
e (N
)HDPE PP HIPS PETG ABS PMMA PVC
Comparison of various PELDPE, LLDPE, MDPE @ 60 mm/s
0
510
1520
2530
35
0 20 40 60 80
Depth, mm
Forc
e, lb
f LDPE120LLDPE120MDPE120
Effect of Forming Temperature
0
2
4
6
8
10
12
14
125 145 165 185
Temperature (C)
Fo
rce
(N)
ABS
PP
HDPE
HIPS
PETG
PMMA
ACETAL
Force100 = f (T, V, material)®F(ABS) =9.2348 -0.0547 T (R2 =99%)®F(PMMA)=7.1587 -0.0341 T(R2=98%)®F(PETG)=10.096 -0.0601 T (R2=92%)®F(HIPS)=9.6782 - 0.0503T(R2=93%)®F(HDPE)=5.2771 -0.0266 T (R2=86%)
Effect of ThicknessPC/ABS, 40 mm/sec, 200 C
0123456789
0 20 40 60 80 100
Depth (mm)
Froc
e (lb
f)
95 150 250
Lot to lot variation in TPO170 C, 40 mm/second, 190 mil
0123456789
10
0 10 20 30 40 50 60 70
Depth (mm)
Froc
e (lb
f)1-1 1-2 1-3
Effect of Color Co PP, 160 C, 40 mm/second, 35 mil
00.10.20.30.40.50.60.70.8
0 20 40 60 80 100 120
Depth (mm)
Forc
e (lb
)
0
2
4
6
8
10
12
blue red Metallic
Effect of thickness on the Heating Rate
050
100150200250
0 500 1000time (sec)
Surfa
ce
Temp
eratur
e(C)
100 mil 150 mil 250 mil
Effect of % Regrind on formability TPO20% regrind / Five Successive Extrusions
0123456
40 60 80 100 120
Forming Distance, mm
Form
ing Fo
rce,
Lbf
1st2nd3rd4th5th
Effect of % Regrind in FR-ABS
0
2
4
6
8
10
12
14
0 20 40 60 80 100
Depth (mm)
Froc
e (lb
f)
50% RG 100% RG
Comparison of filled vs. HMS-TPO
0
10
20
30
40
50
0 20 40 60 80 100
Distance (mm)
Forc
e (N
)40HMSTPO 20HMSTPO
40 FTPO 20FTPO
Effect of adding HMSPP in PP
01234567
40 60 80 100 120 140Form ing Dist ance, mm
Form
ing
Forc
e, L
bf
10%H MSPP 20%HMS PP 30% HMSPP
01234567
40 60 80 100 120 140Form ing Dist ance, mm
Form
ing
Forc
e, L
bf
10%H MSPP 20%HMS PP 30% HMSPP
01234567
40 60 80 100 120 140
Forming Distance, mm
Form
ing
Forc
e, L
bf10%HMSPP 20%HMSPP 30%HMSPP
Formability of HMSPP/PP Blends
02468
1012
10 20 30
% HMSPP
thic
knes
s (H
igh/
Low)
Comparison of Test MethodsRelaxation Time (s) Vs. Force @ 75 mm depth
R2 = 0.9968
02468
1012
0 2 4 6 8
Relaxation Time (sec)
Form
ign
Froc
e (7
5 m
m)
PP, 165 C
HDPE,140CHIPS,160 C
Processing window for E-3500170 C, 40 mm/s, 190 mil
0
10
20
30
0 20 40 60 80 100
Depth (mm)
Force
(lbf)
170 180 190 170TPO
Technoform FeaturesBasic Standard Advanced
Fixed heaters, 120 V Manual Adjustment Automated Adjustment = F (thickness, material)
Fixed Watt Fixed Watts Close loop
Chamber at Ambient Chamber T control Chamber T control
Speeds 0-120 mm/s 0-200 mm/second 0-200 mm/second
Plug T @ ambient Plug T @ ambient Plug T Controlled
Plug mode only Plug and Vacuum Plug and Vacuum
No Vacuum mode No Vacuum vs. depth Vacuum vs. Depth record
Basic software Basic Software Advanced features
Conclusions® Technoform is a simple to operate test
equipment is which closely reflects all unit steps of the typical thermoforming process and generates quantitative and repeatable information in short time.
® The test data can be used in raw form to compare or contrast various materials, process parameters or can be further modeled as a design or predictive tool.
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