Frequency Analysis of Pressure Fluctuations in a Single Screw Extruder
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J. Becker
Abstract
This paper demonstrates the usefulness of frequency analysis in monitoring flow behavior in a single-screw extruder fitted with a capillary die with a length to diameter aspect ratio of 20. The melt pressure in the barrel and die was measured by a transducer, and the pressure fluctuations processed in a Fast Fourier Transform (FFT) frequency analyzer. The pressure fluctuations were studied under various processing conditions for high density polyethylene, linear low density polyethylene and polypropylene. In general, stable extrudate flow generates a noise spectrum with low intensity, the intensity increasing with the level of instability. The machine vibrations appeared to have a direct effect on flow stability. Also, unstable melting of the resin along the screw resulted in an increase in noise level. It seems probable that the frequency of the surface distortions can be related to the shape of the noise spectrum. In general, although more complex in nature, the noise results related to melt flow in the extruder were in agreement with data reported for capillary flow using a piston rheometer.
© 1991, Carl Hanser Verlag, Munich
Articles in the same Issue
- Contents
- Contents
- Review Paper
- Existing Scale-up Rules for Single-screw Plasticating Extruders
- Internal Mixers
- Scale-up Effect in Internal Mixers
- Mixing and Extrusion of High Silica and all Silica-natural Rubber Compounds
- Screw Extrusion
- An Analytical Model of Partial and Thorough Melting in Single-screw Extruders
- Dimensionless Non-Newtonian Isothermal Simulation and Scale-up Considerations for Modular Intermeshing Corotating Twin Screw Extruders
- Erratum
- Die Extrusion
- Extrusion of Rubber Compounds and Highly Filled Thermoplastics through Coathanger Dies
- Pressure Oscillations during Capillary Extrusion of High Density Polyethylene
- Frequency Analysis of Pressure Fluctuations in a Single Screw Extruder
- Fibers and Films
- Orientation and Mechanical Property Development in the Melt Spinning of Fibers from Polyetherimide and Polyarylate
- Study on the Formation of β-Crystalline from Isotactic Polypropylene Fiber
- Biaxially-oriented Polyethylene Films by Compression of Injected Moldings
- Modelling of the Cooling of Semi-crystalline Polymers during their Processing
- Molding
- Non-isothermal Mold Filling and Curing Simulation in Thin Cavities with Preplaced Fiber Mats
- Predicting the Skin-Core Boundary Location in Injection Moldings
Articles in the same Issue
- Contents
- Contents
- Review Paper
- Existing Scale-up Rules for Single-screw Plasticating Extruders
- Internal Mixers
- Scale-up Effect in Internal Mixers
- Mixing and Extrusion of High Silica and all Silica-natural Rubber Compounds
- Screw Extrusion
- An Analytical Model of Partial and Thorough Melting in Single-screw Extruders
- Dimensionless Non-Newtonian Isothermal Simulation and Scale-up Considerations for Modular Intermeshing Corotating Twin Screw Extruders
- Erratum
- Die Extrusion
- Extrusion of Rubber Compounds and Highly Filled Thermoplastics through Coathanger Dies
- Pressure Oscillations during Capillary Extrusion of High Density Polyethylene
- Frequency Analysis of Pressure Fluctuations in a Single Screw Extruder
- Fibers and Films
- Orientation and Mechanical Property Development in the Melt Spinning of Fibers from Polyetherimide and Polyarylate
- Study on the Formation of β-Crystalline from Isotactic Polypropylene Fiber
- Biaxially-oriented Polyethylene Films by Compression of Injected Moldings
- Modelling of the Cooling of Semi-crystalline Polymers during their Processing
- Molding
- Non-isothermal Mold Filling and Curing Simulation in Thin Cavities with Preplaced Fiber Mats
- Predicting the Skin-Core Boundary Location in Injection Moldings
