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The Flow Behavior of Core Material and Breakthrough Phenomenon in Sandwich Injection Molding

Part I: Dependence on Viscosity and Injection Speed of Skin/Core Materials
  • D. Watanabe , U. S. Ishiaku , T. Nagaoka , K. Tomari and H. Hamada
Published/Copyright: June 3, 2013
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International Polymer Processing
From the journal International Polymer Processing Volume 18 Issue 4

Abstract

The processing variables that control the occurrence of breakthrough phenomenon in sandwich injection molding were investigated. Particular attention was paid to the conditions that would yield an optimum sandwich molded part. The effects of variation of core volume ratio that would yield optimum core shot size, injection speed and the skin/core viscosity ratio were examined. The flow morphology at the various stages of flow was also explored. The study was conducted with a bar-flow mold mounted on a twin-barrel injection machine fitted with a common nozzle. It was noted that the core material flow distance depends on the core cylinder screw metering position (core shot size). At the stage at which the core material completely penetrated through the skin material (breakthrough), four distinct regions of flow could be identified. The flow distance of the core material is controlled by the injection speed of the core material while the injection speed of the skin material is of little significance. In order to increase the flow distance of the core material, it is effective to increase the core material injection speed albeit limited by an optimum value of screw metering position. It was found that the flow distance of the core material was longer when the core material viscosity was lower than that of the skin material but breakthrough occurred much earlier so core volume is limited. Breakthrough failed to occur when the viscosity of the core material was higher than that of the skin material. It was found that optimum core volume and core distribution occurred when skin/core viscosities were intermediate. The morphology of the skin material leading to breakthrough was also analyzed.

* Mail address: U. S. Ishiaku, Advanced Fibro Science, Kyoto Institute of Technologie, Matsugasaki, Sakyo-Ku, Kyoto, 606-8585, Japan
Received: 2003-4-25
Accepted: 2003-8-14
Published Online: 2013-06-03
Published in Print: 2003-12-01

© 2003, Carl Hanser Verlag, Munich

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  1. Contents
  2. Contents
  3. Editorial
  4. Fourth of a Series: Pioneering Polymer Industry Developments: The First Continuous Kneading Machines
  5. Screw Extrusion
  6. Prediction of Residence Time Distribution in EZ and KE Element of a Ko-Kneader by using CFD Method
  7. Computational Study of Velocity Field in the KE Element of a Modular Ko-Kneader with CFD Method
  8. Optimization of Sweet Bread Dough Processing Conditions by Twin Screw Extrusion
  9. Experimental Development of Processing Technology for Yuba-like Films Using Twin Screw Extrusion
  10. Die Extrusion
  11. Flow Analyses in a Spiral Mandrel Die Assuming Wall Slip
  12. Effect of Elongational Viscosity on the Flow in a Flat Die
  13. Measuring Polymer Melt Density and Viscosity in Real-time during Extrusion Processes using Ultrasound Sensors Fusion
  14. Film
  15. Scale-up Rule for Double Bubble Tubular Process of PA6 Film
  16. Molding
  17. Analysis of the Morphological Development of PBT/ABS Blends during the Twin Screw Extrusion and Injection Molding Processes
  18. Investigation of the Mechanical Properties and Chemical Resistance of PC/PBT/Impact Modifier Blends
  19. Structure Development in Injection Molding of Isotactic Polypropylene, its Blends, Compounds and Dynamic Vulcanizates
  20. The Flow Behavior of Core Material and Breakthrough Phenomenon in Sandwich Injection Molding
  21. The Flow Behavior of Core Material and Breakthrough Phenomenon in Sandwich Injection Molding
  22. PPS News
  23. PPS News
https://doi.org/10.3139/217.17522

Articles in the same Issue

  1. Contents
  2. Contents
  3. Editorial
  4. Fourth of a Series: Pioneering Polymer Industry Developments: The First Continuous Kneading Machines
  5. Screw Extrusion
  6. Prediction of Residence Time Distribution in EZ and KE Element of a Ko-Kneader by using CFD Method
  7. Computational Study of Velocity Field in the KE Element of a Modular Ko-Kneader with CFD Method
  8. Optimization of Sweet Bread Dough Processing Conditions by Twin Screw Extrusion
  9. Experimental Development of Processing Technology for Yuba-like Films Using Twin Screw Extrusion
  10. Die Extrusion
  11. Flow Analyses in a Spiral Mandrel Die Assuming Wall Slip
  12. Effect of Elongational Viscosity on the Flow in a Flat Die
  13. Measuring Polymer Melt Density and Viscosity in Real-time during Extrusion Processes using Ultrasound Sensors Fusion
  14. Film
  15. Scale-up Rule for Double Bubble Tubular Process of PA6 Film
  16. Molding
  17. Analysis of the Morphological Development of PBT/ABS Blends during the Twin Screw Extrusion and Injection Molding Processes
  18. Investigation of the Mechanical Properties and Chemical Resistance of PC/PBT/Impact Modifier Blends
  19. Structure Development in Injection Molding of Isotactic Polypropylene, its Blends, Compounds and Dynamic Vulcanizates
  20. The Flow Behavior of Core Material and Breakthrough Phenomenon in Sandwich Injection Molding
  21. The Flow Behavior of Core Material and Breakthrough Phenomenon in Sandwich Injection Molding
  22. PPS News
  23. PPS News
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