1:30 pm – 6:00 pm:
T12-Extrusion: Single Screw
(Moderator: Paul Andersen)-Room S320F
1:30 pm – 2:00 pm:
Extrusion Performance Analysis Protocol
David Kazmer, UMass Lowell
Instrumentation and analytical methods are presented for on-line, real-time analysis of performance in single screw extrusion processes. The methodology implements analytical models for heating and cooling power for each zone, screw torque, apparent viscosity, and specific energy. In additional, numerical methods are implemented to provide real-time estimate of the process variation. The protocol defines volumetric, adiabatic, theoretical, and robustness efficiency measures useful for extrusion process engineering and optimization. Validation data is provided for general-purpose and barrier screw designs.
2:00 pm – 2:30 pm:
Melting and Residence Time in the Single Screw Extrusion
Clemens Martin Grosskopf, Department of Plastics Technology, University of Applied Sciences, Darmstadt, Germany
The image analysis of the investigation of the melting process, as Maddock has already done in 1959, is further developed by means of modern image analysis. The experiments are carried out on the two most common screw types in the plastics industry: the general-purpose screw and barrier screw. Control of the residence time is essential for the production of high-quality products and is also important for biodegradable and other time-sensitive polymers. The results indicate that both the general- purpose screw and the barrier screw have significant stagnation zones and broad residence time distribution.
2:30 pm – 3:00 pm:
A Network-Analysis-Based Comparative Study of the Throughput Behavior in Double Wave Screw Geometries
Hans-Juergen Luger, Institute of Polymer Extrusion and Compounding
We present a systematic approach based on networks that uses tensor algebra and numerical methods to model and calculate selected double wave screw geometries in terms of pressure-throughput behavior. Due to the extreme diversity of their geometries, describing the flow behavior is difficult and rarely done in practice. Three-dimensional CFD methods (finite-element or finite-volume) are well capable of calculating the flow behavior in complicated geometries, but they require vast computational power, large quantities of memory, and consume considerable time to create a geometric model created by computer-aided design (CAD). Consequently, a modified 2.5-dimensional finite-volume method, termed Network Simulation Method (NSM) is preferable. The main goal of this study was to compare the results of the NSM with CFD. The results for isothermal melt-dominant flow correlated well. With recently developed pressure-/throughput models for two- and three-dimensional flow of shear-thinning fluids the accuracy of NSM could be further improved. This makes network analysis a valid and easy-to-use tool for screw calculations in practice.
3:00 pm – 3:30 pm:
Use of Pressure and Temperature Profile Inside an Extruder for Optimizing/Troubleshooting Extrusion Processes
John W.S. Lee, LS Cable & System
This paper introduces 5 different types of extrusion problems in production scale ranging from formulation issues to screw design problem. Each extrusion problem was analyzed and diagnosed by using a highly instrumented pilot-scale extruder, equipped with 14 pressure/temperature transducers along the axis of an extruder barrel. The case studies will demonstrate how pilot-scale extrusion results can be correlated with the production-scale extrusion problem, and how the measured pressure and temperature data can be used to optimize and troubleshoot production-scale extrusion problems.
3:30 pm – 4:00 pm:
Cost Analysis for Installing New and Optimized Screws for Single-Screw Extrusion Lines
Mark A. Spalding, The Dow Chemical Company
Optimization of an extrusion process for maximum rate and product quality can lead to substantial cost reductions. The value to the converter can be very large and thus the payback period can be very short. This paper discusses the economic evaluations of two commercial case studies.
4:00 pm – 4:30 pm:
A Simple System Analysis for the Small Extrusion Screw and Die
Jingyi Xu, Graham Engineering Corporation
A simple system analysis for the small screw and die in extrusion line is one of the keys to design the screw and optimize the machine performance. It explains several critical issues and features of plasticizing and extrusion performances in small extruder and die. This simplified model of small extruder will be used to analyze the size of the screw and specific die with different screw parameters as a system. The result is useful to design the small size screw, and to optimize the performance of the small extruders.
4:30 pm – 5:00 pm:
Examination of Power Consumption on Melt Spinning: Mono and Bi-Component Fibers
Javier Vera Sorroche, UMass Lowell
The power consumption of a melt spinning extrusion module with mono and bi-component capability was under consideration, especially when analyzing the effects of process settings and downstream equipment on the total power consumption of the extrusion line. Experiments were conducted to quantify in real-time the effects of barrel temperature profiles, godet roll temperatures and godet roll speeds on the total power consumption when the extrusion line was operated to produce both mono and bi-component fibers. Between the effective use of extrusion processing conditions and optimization of the downstream equipment, the results have shown that there is a significant opportunity to save energy for the total power consumption. In bi-component mode, the downstream equipment was found to cause the highest effect on the total energy consumption. In mono-component mode, an optimal combination between metering pump and extruder motor appeared to be crucial for the optimization of the melt spinning system. Specific energy consumption was more favorable when the metering pumps were operated at higher speeds.
5:00 pm – 5:30 pm:
Investigation on the Effects of the Processing Parameters on the Replication Quality of Micro-Structures in the Extrusion Embossing of Polycarbonate Films
Florian Petzinka, Institute of Plastics Processing
The application of micro-structures enables the integration of new functionalities on product surfaces. Though some applications have successfully been introduced on the market, widespread use of the full potential is depending on efficient and economical production processes. For plastics films the variothermal extrusion embossing process enables a quick and cost efficient replication of micro-structures on large areas. To achieve high quality replication, the process has to be finely tuned to the desired geometry. In this paper, the effects of the processing parameters on the replication quality inside previously established processing windows are investigated for two polycarbonate materials. The replication quality is evaluated for three different micro-structures. The experiments confirm strong interdependencies between the processing parameters, the material behavior and the geometric features of the micro-structures. These lead to partly contrary effects on the replication quality for different micro-structures and make the prediction of the optimal processing parameters for any given geometry very difficult.
5:30 pm – 6:00 pm:
Effective of Scale up on Thermal Homogeneity and Energy Efficiency in Single Screw Extrusion
Javier Vera Sorroche, UMass Lowell
Extrusion scale up is the procedure of replicating a plastic extrusion process in order to predict the performance of large production size extruders on the basis of geometrically similar small extruders. Extrusion processes are often developed on small extruders, so the effective scale up of these extrusion processes is very desirable as a means of increasing production rates. Although, studies on scale up procedures have been performed for several decades, no further studies have been undertaken to examine the influence of screw geometry on extrusion performance and energy consumption. In this work, in-process monitoring techniques incorporating thermocouple grid sensors and an energy meter have enabled real time examination of the extruder scale up by comparing the thermal and energy characteristics of a 38 mm diameter single screw extruder to that of a similar extruder with 63.5 mm screw diameter. Experiments, employing identical screw geometries, extruder set temperatures and range of screw speeds, were carried out on both machines with LDPE to quantify the effect of extruder scale on the measured throughputs, melt temperature homogeneity, die pressure and energy consumption.