The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
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Parison Formation in Blow Molding: Parison Dimension Prediction using Neural Network Model
The parison dimension distributions during the parison formation in extrusion blow molding were determined by analyzing video images of the parison. Two BP neural network models were developed based on the experimental data. The prediction of the parison diameter and thickness distributions can be made on line at any parison length or any parison drop time within a given range using the models.
Part Cooling in Blow Molding: Finite Element Solution
The part cooling stage of the extrusion blow molding process was simulated based on the ANSYS finite element software. The transient temperature profiles across the part thickness were predicted. The experiment results validated that the predictions are reasonable. Then the temperature dependent quiescent crystallinity development across the thickness was calculated using a Nakamura equation. The influence of the processing parameters, part thickness, and the thermal properties of plastics and mold materials can be analyzed.
The Residual Melt Layer Thickness as New Criterion for Ultrasonic Welding
Even today, setting up the process and finding the optimum parameter set for ultrasonic welding sometimes is a big problem. As the residual melt layer thickness is directly linked to the formation of the joint, a real improvement in setting up the process can be achieved by using it as determining criterion.
Characterization of Ultrasonic Plastic Welding Parameters in Lessening the Need for a Design of Experiment (DOE) Analysis
DOE is a powerful tool used in various process optimizations. In many cases, time and resources are overextended, making this tool unaffordable or impractical. With experimentation, it has been demonstrated that the time-consuming task of using DOE to determine the contribution of a parameter to a welded product, as well as the development of a model that predicts behavior, can be drastically reduced if the parameter characterizations presented in this paper are utilized.
Laser Marking for Automotive Interiors
Laser marking continues to gain acceptance as a preferred means for decorating parts found in automotive interiors. Beam steered laser technology presents a versatile and robust means for applying any design to a wide variety of materials. This paper will cover the fundamentals of laser technology including an overview of key parameters that a design engineer will find useful in supporting a reliable implementation on the production floor.
Automate or Perish: The Future of Pad Printing
Every day another company loses a pad printing application to a more efficient competitor. Many times a paradigm shift away from a vicious cycle of under-investment is necessary for companies to remain competitive.
Extrusion Simulation and Experimental Validation to Optimize Precision Die Design
A CFD-simulation is performed for an existing die and compared with the actual polymer flow and dimensions of the extrudate. Experimental validation of the simulation is used to improve new die design by integrating flow simulation through the 3-D die geometry and the free-surface flow with swelling after the die. Modified die-land-and-lip profile is optimized using the so-called inverse extrusion" simulation with an objective to improve accuracy of extrudate dimensions."
Effect of Elongational Viscosity on the Flow in a Spiral Die
Three-dimensional flow of a low-density polyethylene in a spiral die for blown-film extrusion is simulated. Effect of elongational viscosity on the flow in the spiral die is analyzed. Elongational viscosity is found to have significant effect on the velocity distribution at the die exit and on the pressure and temperature distributions in the die.
Automatic Balancing of Profile Extrusion Dies: Experimental Assessment
In this work a previously developed die design code is used to optimise the flow distribution of a profile extrusion, using two alternative strategies. The numerical predictions are compared with experimental data gathered during extrusion experiments, the results of which are used to assess the rheological code and the effectiveness of the optimisation algorithm and design strategies implemented.
Eliminating Surface Melt Fracture using PPA: The Role of PPA Domain Size
The investigation of the elimination of sharkskin using polymer processing aids (PPA) requires the consideration of factors such as: PPA domain size, operational shear rate and matrix/PPA viscosity ratio. In this work, the role of PPA droplet size in the elimination of surface melt fracture was investigated. The parameters monitored were the die entrance pressure, the PPA coating thickness and the extrudate appearance. We found a substantial enhancement in coating thickness and speed upon increasing the droplet size.
Modeling of Viscoelastic Coextrusion Flows in Multi-Manifold Flat Dies
A recently proposed modification of the viscoelastic Leonov model is employed as a stress calculator in FEM analysis with a full u-v-p-? numerical scheme of the coextrusion flow in multi-manifold flat dies with 30 and 90 degree entrance angles. It is shown that the predicted stresses, interface location and streamlines fields are in a good agreement with the measurements. It is also revealed that the extensional viscosity has to be used in the modeling of the coextrusion flow to confirm experimental data.
Elongational Flow in Multiple Screw Extruders
Flows of a low-density polyethylene in a co-rotating twin-screw extruder and in a twelve-screw ring extruder are compared. Effect of the shear as well as elongational viscosity of the low-density polyethylene is included in the simulation. Even though the velocity and pressure distributions in the two extruders have many similarities, because the intermeshing regions constitute a larger fraction of the ring extruder than that of the twin-screw extruder, the degree of elongation, and hence, the quality of mixing, is found to be better in the ring extruder.
Kinematics Model of Solids Conveying of LDPE
The kinematics model of solids conveying shows that the solids advance angle is a single empirical factor of solids flow in lieu of friction factors. Furthermore, solids advance angle can be linearly correlated with pressure for LDPE. The linear functions that approximate the solids angle are used with the kinematics model to calculate solids flow of LDPE. The calculations are compared to data to demonstrate the accuracy of the model.
Entropic Mixing Characterization in a Single Screw Extruder
The quality of distributive mixing is evaluated via an entropic measure of color homogeneity. We first illustrate this technique in a numerically built rectangular channel representing the unwounded channel of a single screw extruder. We also apply this method for assessing mixing quality of experimentally obtained samples when mixing a color concentrate in ABS resin in a single screw extruder. We discuss application of this technique in numerical simulations of processing equipment.
Melt Temperature Homogeneity in Single Screw Extrusion: Effect of Material Type and Screw Geometry
Thermocouple meshes have successfully been used to measure melt temperature across the material exiting from a 60mm single screw extruder. Temperature profiles are shown to be dependent on screw geometry, set wall temperatures, throughput and material type. Differences in average temperature profile and transient fluctuations have been determined.
Design and Validation of Self-Compensating Melt Regulator for Plastics Extrusion
A design for a self-adjusting melt pressure regulator is presented for use between an extruder and one or more dies. The regulator is derived from a low force valve design that enables the outlet pressure to be directly regulated by a provided force on a valve pin without need for pressure sensors or a closed loop control system. Analytical and experimental results indicate an excellent level of response and consistency given the simplicity of the design.
Experimental Observations of LDPE Melt Flow in Coextrusion Geometries
Flow visualisation studies are preformed to determine the effects of die geometry on interfacial instabilities in coextrusion flows of a LDPE melt. Slit coextrusion visualisation cells with 30° and 90° convergent stream angles are used in this study. Stream ratios leading to interfacial instability in the LDPE melt are quantified and compared for each geometry.
Experimental and Numerical Studies of Blown Film Cooling
Studies of blown film cooling were carried out to investigate interaction of cooling air flow and the heat transfer processes. Instabilities in the air flow were detected at several point in the cooling region which influences the local heat transfer.The results indicates the development of temperature fluctuation in the bubble which seem to be one of the main reasons for the formation of film thickness profile in extrusion direction.
The Effect of Extrusion Conditions and Material Properties on the Gas Permeation Properties of LDPE/LLDPE Silage Wrap Films
This work investigates the effect of extrusion processing conditions and co-monomer type on the gas permeation properties of LLDPE films containing polyisobutylene (PIB). The results show improved gas barrier properties with increasing polymer density and increase in film crystallinity and orientation as a result of extrusion processing conditions such as blow up ratios.
A Modeling of the Film Blowing Process by using Variational Principles
A simple equation with only four physical parameters for the description of the bubble shape (including HDPE wine-glass shape) has been derived from variational principles. The proposed equation was used in modeling of the film blowing process for a variety of process conditions and polymer melts, and a very good agreement between measured and simulated data was found.
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