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What Lies Below the Surface of Your Molded Parts?

What Lies Below the Surface of Your Molded Parts?. Plastics Manufacturers Strength: • Throughput Efficiency • Focus has been on Lean Manufacturing Principals • New Work Cells • Improving Plant Layouts • Streamlining the Process from Molded Part to Loading the Truck. Revenue / ft 2. 2008.

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What Lies Below the Surface of Your Molded Parts?

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  1. What Lies Below the Surface of Your Molded Parts?

  2. Plastics Manufacturers Strength: • Throughput Efficiency• Focus has been on Lean Manufacturing Principals • New Work Cells• Improving Plant Layouts• Streamlining the Process from Molded Part to Loading the Truck Revenue / ft2 2008 Present

  3. Plastics Manufacturers Weakness: • • Development and Commissioning New Projects• Grass Roots Approach • hurry up, make mistakes, try something else • just find away to get this part to meet specification • we’ll figure out how to make money at it on the backside Product Design Mold Design Part & Mold Commissioning Concept Launch CIP Production

  4. So you followed all of the design guidelines and scientific molding procedures and you still ended up with part variations. What could possibly be going wrong? Identical runner lengths Identical channel radius Identical gate geometry Identical cavity sizes I. Mold Steel Variations (l, r) II. Rheological Variations (η )

  5. Why is New Mold Commissioning Such a Challenge? • • Plastic Rheology is Not Well Understood • Shear-induced imbalances • Shrink & Warp characteristics • Cooling and thermodynamics • Regional pressure variations • Amorphous and Semi-crystalline materials

  6. The Science Behind Non-Uniform Rheology • Plastic is a Non-Newtonian Material • Viscosity is affected by Shear Rate and Temperature • As shear rate increases, viscosity decreases • As temperature increases, viscosity decreases • Highest Shear Rate is just inside the frozen layer • Shear-thinning and Shear-heating reduce viscosity in these laminates

  7. Influence on melt front advancement profile • Single Cavity Disk Mold: • Rivering flow front • Gas trap created

  8. 4 3 1 1 1 1 1 2 4 3 2 2 2 2 2 4 3 4 3 Melt Property Distribution

  9. More than just a “filling imbalance”... Temperature differences result in shrink variations * Forces process technician to increase cooling time and use mold as a cooling fixture to minimize difference between part Result = Increase Cycle Time Conventional Runner

  10. Volumetric: Mold Design (Cooling) 100° F Linear Shrinkage: 180° F At ejection:

  11. ΔP at End of Fill 55 Mpa 40 Mpa ΔP Thick Part 55 mPa 40 mPa x ΔP Thin Part 70 mPa 25 mPa Effect of Regional Pressure Differences Center packs under higher pressure = possible dome warp Can this be processed out? Packing profile can be ramped Must also consider processing effects

  12. Linear Polymers oriented in direction of flow Extensional Expanding flow front (center-gated disk) Dependent on part thickness and processing Polymers oriented in the extensional or radial direction Transient Flow direction changes during mold filling Orientation-Induced Shrink: Flow Types

  13. Different filling pattern change orientation and shrinkage Warp in Cavities 1 & 4 Warp in Cavities 2 & 3

  14. Intersection Options • Be careful of putting too much faith in simulation output. Put it through a reality check with your understanding of plastic flow.

  15. Solution: Patented In-Mold Rheological Control Systems • Continually manage the melt properties within the runner system through strategic repositioning of the high sheared laminates • Two Rotation Types: • Single-Axis Symmetry • Multi-Axis Symmetry Multi-Axis Single-Axis

  16. Solution: Patented In-Mold Rheological Control Systems + Intra-Cavity Control Naturally “Imbalanced”

  17. Mold Layout Melt Rotation: Intra-Cavity Control, Concentricity Effective Melt Temperature Concentricity Conventional Melt Rotation Conventional Avg. ∆T = 39.3°F Melt Rotation Avg. ∆T = 4.8°F

  18. Engineering for Success Systems of the mold: • Structural / Kinematic • Melt Delivery • Air Evacuation (Venting) • Cooling • Ejection

  19. Cooling Strategies

  20. Cooling System: Is there turbulent flow? How conductive is the mold steel? What is the heat capacity of the material? What is the thermal diffusivity? Will the improvements be measurable?

  21. The Challenge: • • Learn what is needed to Engineer for Success • • We can be good program managers, exceptional engineers, and • good stewards of our companies • Identify areas for improvement • Seek out the appropriate training courses that will help everyone in the • organization Engineer for Success

  22. “Teaching you to Think From the Plastic’s Perspective... From Design through Production” Course 1: “Mold Start-up, Debug & Qualification” Course 3: “Injection Molding & Root Cause Analysis for QC/QA” Course 5: “Mold Design for Project Engineers” Course 7: “Understanding & Applying Flow Simulation” • Course 2: • “Hot & Cold Runner Systems” • Course 4: • “Understanding Shrink & Warp” • Course 6: • “Plastic Flow & Design Essentials for Mold Makers/Designers”

  23. Benefits: • Improve Competitiveness on the Global Stage • Improve Customer Satisfaction • Reduce Mold Commissioning Time and Costs • Produce Higher Quality Parts at a Lower Cost

  24. Next Steps: • • Sharpen the Saw • Identify areas for improvements within your • organization • Seek out appropriate training courses that will • improve your ability to Engineer for success • Apply what is learned • Measure Results • Repeat

  25. Beaumontinc.com

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