Technoform – For Rapid, Repeatable Thermoformability Analyses

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

11. TECHNOFORM TM TTG PatentPending TECHNOFORM

12. Schematics of Technoform

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 Strain hardening Thinning Thermoformability Index= slope SagDistance Forming Depth mm

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

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 Temperature35 Mil Black HIPS, 130 C,40 mm/s- No control -

19. Effect of controlling Plug TemperatureHIPS, 40 mm/second with T control

20. Effect of Plug Geometry

21. Effect of plug materialHIPS, 170 C, 40 mm/second, 35 mil

22. Effect of forming Speed on HDPE @ 150 C

23. Heating rates for various plastic materials(Heater at 600 C, 3” from upper, 2” from lower)

24. Effect of Crystallinity

25. Comparison of various PE

26. Effect of Forming Temperature

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 ThicknessPC/ABS, 40 mm/sec, 200 C

29. Lot to lot variation in TPO170 C, 40 mm/second, 190 mil

30. Effect of Color Co PP, 160 C, 40 mm/second, 35 mil

31. Effect of thickness on the Heating Rate

32. Effect of % Regrind on formability TPO20% regrind / Five Successive Extrusions

33. Effect of % Regrind in FR-ABS

34. Comparison of filled vs. HMS-TPO

35. Effect of adding HMSPP in PP

36. Formability of HMSPP/PP Blends

37. Comparison of Test Methods

38. Processing window for E-3500170 C, 40 mm/s, 190 mil

39. Technoform 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.