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THERMOFORMING High Density Polyethylene sheet using Temperature-CONTROLLED ALUMINUM TOOLING

Brett Braker MET496 April 28 th , 2011. THERMOFORMING High Density Polyethylene sheet using Temperature-CONTROLLED ALUMINUM TOOLING. Individual Performance Objectives. Show the importance of temperature-controlled molding in thermoforming.

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THERMOFORMING High Density Polyethylene sheet using Temperature-CONTROLLED ALUMINUM TOOLING

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  1. Brett Braker MET496 April 28th, 2011 THERMOFORMING High Density Polyethylene sheet using Temperature-CONTROLLED ALUMINUM TOOLING

  2. Individual Performance Objectives • Show the importance of temperature-controlled molding in thermoforming. • Prove that HDPE can be a relevant material to use in thermoforming, instead of just amorphous materials. • Get project results by spring break, ± one week • Create a lab for future curriculum

  3. Purpose • Almost all of thermoforming industry uses amorphous materials • Use molds that are not temperature-controlled • Material options = Better quality parts

  4. Material • 50 High Density Polyethylene sheets • 22.5” (MD) x 40” (TD) x 0.125” • Levant finish on top, smooth bottom • 285-385°F forming temp, 330°F optimum • 170°F ejection • Density: 0.0345 lb/in3 (0.955 g/cc) • 66.3 Shore D hardness • Ultimate Tensile Strength: 3,800 psi • Tensile Yield Stress: 3,829 psi • Deflection temp with 66 psi: 166.5°F

  5. Grid Layout • Original Idea • Penn College Printing Department • Pat Bundra • Screen Printing

  6. Non Temperature-Controlled Mold • Renshape 472 Medium Density Polyurethane Board (REN) • Wooden base, machined Polyurethane core • Exact same dimensions as aluminum mold • 15.25” x 33.125” x 4.2”

  7. Renshape Cycle • Bottom platen • Material Build-up • Stretching • Material Properties

  8. Renshape Cycle

  9. Renshape Cycle • Top platen • Machine settings

  10. Renshape Cycle • “Perfect” cycle • Rails too close • Mold too deep • Ovens too hot

  11. Production-Style Run • 10 parts • Continuous cycle • Measurements • Temperatures • Aluminum Jig • Thicknesses • 2 minutes after forming • 24+ hours after forming

  12. Temperature Measurements • Mold • Front • Top • Back • Sheet temp before and after forming • Room temperature • Humidity • All taken with infrared gun

  13. Aluminum Jig Measurements • 15.875” x 33.500” • Corner 3-4 • Height • 5.562” • 5.562 – x = h • Jig thickness • Aluminum blocks • Meter stick height • Dial calipers

  14. Thickness Measurements • Drill with hole saw attachment • 1-inch holes • Left, Right, Front, Back, and Top of part • 2 minutes – Left side • 24+ hours – Right side • Discs • Dial calipers

  15. Measurement Formulas • After jig measurements • Match corresponding points (1-8, 6-3, 5-9, etc.) • Take combination of both and subtract from jig dimension • Y1 = 15.875 – (0.1025 + 0.4865) • Y1 = 15.2860” • Points show warpage • Y1 shows shrinkage

  16. Renshape Mold Production • I.R. eye – 370°F • Heating – 120 seconds • Cooling – 180 seconds

  17. Renshape Production Results

  18. Renshape Production Results

  19. Renshape Production Results

  20. Renshape Production Results

  21. Aluminum Mold Production • I.R. eye – 370°F • Changed to 360°F before Sheet 5 • Cooling time – 100 seconds • Changed to 120 seconds before Sheet 4 • Changed to 150 seconds before Sheet 5 • Changed to 130 seconds before Sheet 7 • Changed to 120 seconds before Sheet 8 • Changed to 110 seconds before Sheet 9 • Circulator temp – 200°F

  22. Aluminum Mold Production Results

  23. Aluminum Mold Production Results

  24. Aluminum Mold Production Results

  25. Aluminum Mold Production Results

  26. Renshape vs. Aluminum

  27. Renshape vs. Aluminum

  28. Renshape vs. Aluminum

  29. Renshape vs. Aluminum

  30. Renshape vs. Aluminum

  31. Renshape vs. Aluminum

  32. Design Of Experiment

  33. Design Of Experiment

  34. Renshape Tensile Testing

  35. Aluminum Tensile Testing

  36. Renshape vs. Aluminum

  37. Conclusion • Temperature-controlled aluminum tooling shows much more consistency with HDPE than Renshape does. • Much less warpage, shrinkage, and higher dimensional stability as a result • HDPE needs a temperature-controlled mold to be deemed relevant in the thermoforming industry.

  38. Individual Performance Objectives • Show the importance of temperature-controlled molding in thermoforming. • Prove that HDPE can be a relevant material to use in thermoforming, instead of just amorphous materials. • Get project results by spring break, ± one week • Create a lab for future curriculum

  39. References • Defosse, Matthew. "Thermoforming." Modern Plastics Worldwide World Encyclopedia 2006. Los Angeles, CA: Canon Communications, 2006. 106. Print. • Harper, Charles A. Handbook of Plastic Processes. Hoboken, NJ: Wiley-Interscience, 2006. Print. • Illig, Adolf, and Peter Schwarzmann. Thermoforming: A Practical Guide. Munich: Hanser, 2001. Print. • Peacock, Andrew J. Handbook of Polyethylene: Structures, Properties, and Applications. New York: Marcel Dekker, 2000. Print. • "Sheet/Thermoforming Grade HDPE." www.matweb.com. Material Property Data. Web. <http://www.matweb.com/search/DataSheet.aspx?MatGUID=c35a0a3e740e424fad260a5da2c2b50a&ckck=1>.

  40. Acknowledgements • John Bartolomucci, Pennsylvania College of Technology • Patrick Bundra, Pennsylvania College of Technology • Todd Chrismer, McClarin Plastics • Todd Kennedy, McClarin Plastics • Roger Kipp, McClarin Plastics • Aaron Lapinski, Pennsylvania College of Technology • Gary McQuay, Plastics Manufacturing Center

  41. Questions?

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