Technoform Applications
- 1. Technoform – For Rapid, Repeatable Thermoformability Analyses Dr. Amit Dharia Transmit Technology Group, LLC, TX www.transmit-technology.com
- 2. Outline ® Properties –Thermoforming Process relationship ® Current test methods ® Description of Technoform ® Application and data interpretation ® Products – Basic, Standard, Advanced ® Conclusion
- 3. Thermoforming Process ® Extruding sheet stock ® Heating sheet above Tg ® Stretching heated sheet in rubbery state ® Cooling ® Trimming ® Finishing
- 4. 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
- 5. 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)
- 6. 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)
- 7. 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.
- 8. 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?
- 9. 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?
- 10. 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
- 12. Schematics of Technoform 1 2 3 4 5 7 9 10 12 1113 14 1617 18 19 20 21 22 24 25 26 8 27 1 2 3 4 5 7 9 10 12 1113 14 1617 18 19 20 21 22 24 25 26 8 27 1 2 3 4 5 7 9 10 12 1113 14 1617 18 19 20 21 22 24 25 26 8 27
- 13. 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
- 14. Typical user Input Screen Sag Distance Thinning Strain hardening Forming Depth mm Thermoformability Index= slope
- 15. 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)
- 16. Effect of Heating time Force vs. Depth (180 C, Isothermal) 4" dia hemi-spherical plug, 20 ipm (effect of pre-heat time) 0 10 20 30 40 50 0 20 40 60 Depth, mm Force,lbs 10 min 15 min
- 17. 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
- 18. Effect of Plug Temperature 35 Mil Black HIPS, 130 C,40 mm/s - No control - 0 2 4 6 8 10 12 0 50 100 150 Draw Depth, mm Force,Lbf Series1 Series2 Series3
- 19. Effect of controlling Plug Temperature HIPS, 40 mm/second with T control HIPS @130 C, 40 mm/second Plug cooled for five minutes 0 2 4 6 8 10 12 0 20 40 60 80 100 120 Depth, mm Force,Lbf #1 #2 #3 #4
- 20. Effect of Plug Geometry Force vs. Depth 180 C, 40 mm/s Hemi-Spherical Plug with 4 " Diameter 0 5 10 15 20 25 30 35 0 10 20 30 40 50 Depth mm Force,lbsf 1 2
- 21. Effect of plug material HIPS, 170 C, 40 mm/second, 35 mil 0 1 2 3 4 5 6 0 20 40 60 80 100 120 Depth (mm) Force(lb) WF WFT Bix
- 22. Effect of forming Speed on HDPE @ 150 C Effect of Forming Speed on HDPE 0 2 4 6 8 10 0 50 100 150 Distance (mm) Fromingforce(N) 20 mm/sec 30 mm.sec 50 mm/sec
- 23. 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) PP HDPE HIPS PVC ABS Acetal PMMA Nylon
- 24. Effect of Crystallinity 0 5 10 15 20 25 30 50 70 90 110 130 Forming distance, mm Force(N)HDPE PP HIPS PETG ABS PMMA PVC
- 25. Comparison of various PE LDPE, LLDPE, MDPE @ 60 mm/s 0 5 10 15 20 25 30 35 0 20 40 60 80 Depth, mm Force,lbf LDPE120 LLDPE120 MDPE120
- 26. Effect of Forming Temperature 0 2 4 6 8 10 12 14 125 145 165 185 Temperature (C) Force(N) ABS PP HDPE HIPS PETG PMMA ACETAL
- 27. 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%)
- 28. Effect of Thickness PC/ABS, 40 mm/sec, 200 C 0 1 2 3 4 5 6 7 8 9 0 20 40 60 80 100 Depth (mm) Froce(lbf) 95 150 250
- 29. Lot to lot variation in TPO 170 C, 40 mm/second, 190 mil 0 1 2 3 4 5 6 7 8 9 10 0 10 20 30 40 50 60 70 Depth (mm) Froce(lbf) 1-1 1-2 1-3
- 30. Effect of Color Co PP, 160 C, 40 mm/second, 35 mil 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 20 40 60 80 100 120 Depth (mm) Force(lb) 0 2 4 6 8 10 12 blue red Metallic
- 31. Effect of thickness on the Heating Rate 0 50 100 150 200 250 0 500 1000 time (sec) Surface Temperature(C) 100 mil 150 mil 250 mil
- 32. Effect of % Regrind on formability TPO 20% regrind / Five Successive Extrusions 0 1 2 3 4 5 6 40 60 80 100 120 Forming Distance, mm FormingForce,Lbf 1st 2nd 3rd 4th 5th
- 33. Effect of % Regrind in FR-ABS 0 2 4 6 8 10 12 14 0 20 40 60 80 100 Depth (mm) Froce(lbf) 50% RG 100% RG
- 34. Comparison of filled vs. HMS-TPO 0 10 20 30 40 50 0 20 40 60 80 100 Distance (mm) Force(N) 40HMSTPO 20HMSTPO 40 FTPO 20FTPO
- 35. Effect of adding HMSPP in PP 0 1 2 3 4 5 6 7 40 60 80 100 120 140 Form ing Dist ance, mm FormingForce,Lbf 10%H MSPP 20%HMS PP 30% HMSPP 0 1 2 3 4 5 6 7 40 60 80 100 120 140 Form ing Dist ance, mm FormingForce,Lbf 10%H MSPP 20%HMS PP 30% HMSPP 0 1 2 3 4 5 6 7 40 60 80 100 120 140 Forming Distance, mm FormingForce,Lbf 10%HMSPP 20%HMSPP 30%HMSPP
- 36. Formability of HMSPP/PP Blends 0 2 4 6 8 10 12 10 20 30 %HMSPP thickness(High/Low)
- 37. Comparison of Test Methods Relaxation Time (s) Vs. Force @ 75 mm depth R2 = 0.9968 0 2 4 6 8 10 12 0 2 4 6 8 Relaxation Time (sec) FormignFroce(75mm) PP, 165 C HDPE,140C HIPS,160 C
- 38. Processing window for E-3500 170 C, 40 mm/s, 190 mil 0 10 20 30 0 20 40 60 80 100 Depth (mm) Force(lbf) 170 180 190 170TPO
- 39. Technoform Features Basic 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
- 40. 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.