Practical Limitations to Carrier Layer Formation on Inclined Planes
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J. B. Ikin
Abstract
Two important instabilities associated with carrier layer formation on the inclined plane of slide-fed coating processes are explored, with a two liquid layer prototype configuration employed to mimic the slide-bead process as used by industry. The work relates to both slide-bead and curtain coating methods. Experiments first reveal how broad diffuse bands, that destroy the quality of the final coating, are formed as the carrier layer flow rate is reduced. The bands are found to be exacerbated by either decreasing the viscosity or flow rate of the carrier layer or by increasing the viscosity of the upper layer. As the flow rate of the carrier layer is reduced further, the upper layer begins to invade the carrier layer delivery slot. Flow visualisations reveal that a parallel sided delivery slot is superior to a chamfered one in terms of robustness against invasion of the interface and that reducing the slot width increases robustness further. Experiments and complementary numerical simulations confirm the existence of a recirculating eddy near the top of the downstream wall as the carrier layer flow rate is reduced and this insight is used to propose an instability mechanism for the onset of the bands. Further experiments expose the mechanism for the formation of cross bars. These can develop downstream of the carrier layer delivery slot and arise because the merging of the layers there becomes increasingly influenced by the flow, demonstrating that the sensitivity of cross bars to pump induced disturbances grows rapidly as the critical carrier layer flow rate for instability is approached and then collapses as the flow rate is reduced to a value where the layer is no longer effective in lubricating the flow of adjacent layers.
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© 2007, Carl Hanser Verlag, Munich
Artikel in diesem Heft
- Contents
- Contents
- Editorial
- International Polymer Processing Special Issue: European Coating Symposium 2005, University of Bradford, UK
- Invited Papers
- Coating and Polymer Processing
- Practical Limitations to Carrier Layer Formation on Inclined Planes
- Simulation of 3D Crystallization of Colloidal Nanoparticles on a Substrate during Drying
- Asymmetric Surface Roughness Formationon Moving Non-isothermal Liquid Coatings
- Inkjet Printing of Conductive and Resistive Coatings
- Moisture Sorption and Transport in Polylactide
- 10.3139/217.0992
- Review Article
- Welding of Plastics: Fundamentals and New Developments
- Regular Contributed Articles
- Numerical Simulation of Viscous Flow in a Partially filled Co-rotating Twin Screw Extruder
- Invited Papers
- A New Calculation Model and Optimization Method for Maddock Mixers in Single Screw Plasticising Technology
- Regular Contributed Articles
- Residual Wall Thickness Distribution at the Transition and Curve Sections of Water-assisted Injection Molded Tubes
- Numerical Simulation of Extrusion Coating
- Correlation between Injection Molding Parameters, Morphology and Mechanical Properties of PPS/SEBS Blend Using Artificial Neural Networks
- PPS News
- PPS News
- Seikei-Kakou Abstracts
- Seikei-Kakou Abstracts
Artikel in diesem Heft
- Contents
- Contents
- Editorial
- International Polymer Processing Special Issue: European Coating Symposium 2005, University of Bradford, UK
- Invited Papers
- Coating and Polymer Processing
- Practical Limitations to Carrier Layer Formation on Inclined Planes
- Simulation of 3D Crystallization of Colloidal Nanoparticles on a Substrate during Drying
- Asymmetric Surface Roughness Formationon Moving Non-isothermal Liquid Coatings
- Inkjet Printing of Conductive and Resistive Coatings
- Moisture Sorption and Transport in Polylactide
- 10.3139/217.0992
- Review Article
- Welding of Plastics: Fundamentals and New Developments
- Regular Contributed Articles
- Numerical Simulation of Viscous Flow in a Partially filled Co-rotating Twin Screw Extruder
- Invited Papers
- A New Calculation Model and Optimization Method for Maddock Mixers in Single Screw Plasticising Technology
- Regular Contributed Articles
- Residual Wall Thickness Distribution at the Transition and Curve Sections of Water-assisted Injection Molded Tubes
- Numerical Simulation of Extrusion Coating
- Correlation between Injection Molding Parameters, Morphology and Mechanical Properties of PPS/SEBS Blend Using Artificial Neural Networks
- PPS News
- PPS News
- Seikei-Kakou Abstracts
- Seikei-Kakou Abstracts
