THERMOFORMING High Density Polyethylene sheet using Temperature-CONTROLLED ALUMINUM TOOLING

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THERMOFORMING High Density Polyethylene sheet
using Temperature-CONTROLLED ALUMINUM TOOLING

• Brett Braker
• MET496
• April 28th, 2011

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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

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Purpose

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

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Material

• 50 High Density Polyethylene sheets
• 22.5 (MD) x 40 (TD) x 0.125
• Levant finish on top, smooth bottom
• 285-385F forming temp, 330F optimum
• 170F 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 166.5F

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Grid Layout

• Original Idea
• Penn College Printing Department
• Pat Bundra
• Screen Printing

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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

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Renshape Cycle

• Bottom platen
• Material Build-up
• Stretching
• Material Properties

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Renshape Cycle
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Renshape Cycle

• Top platen
• Machine settings

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Renshape Cycle

• Perfect cycle
• Rails too close
• Mold too deep
• Ovens too hot

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Production-Style Run

• 10 parts
• Continuous cycle
• Measurements
• Temperatures
• Aluminum Jig
• Thicknesses
• 2 minutes after forming
• 24 hours after forming

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Temperature Measurements

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

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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

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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

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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

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Renshape Mold Production

• I.R. eye 370F
• Heating 120 seconds
• Cooling 180 seconds

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Renshape Production Results
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Renshape Production Results
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Renshape Production Results
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Renshape Production Results
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Aluminum Mold Production

• I.R. eye 370F
• Changed to 360F 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 200F

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Aluminum Mold Production Results
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Aluminum Mold Production Results
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Aluminum Mold Production Results
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Aluminum Mold Production Results
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Renshape vs. Aluminum
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Renshape vs. Aluminum
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Renshape vs. Aluminum
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Renshape vs. Aluminum
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Renshape vs. Aluminum
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Renshape vs. Aluminum
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Design Of Experiment
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Design Of Experiment
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Renshape Tensile Testing
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Aluminum Tensile Testing
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Renshape vs. Aluminum
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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.

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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

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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. lthttp//www.matweb.co
  m/search/DataSheet.aspx?MatGUIDc35a0a3e740e424fad
  260a5da2c2b50ackck1gt.

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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

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Questions?