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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PTFE Paste Extrusion: Effect of Physical Properties of Lubricants
Preforming and the physical properties of the lubricants play a crucial role on PTFE paste extrusion. Since the most significant effects on liquid migration are due to viscosity and the wettability, the lubricants were characterized in terms of both flow and surface properties. These two properties were altered independently to study their relative effects on PTFE paste processing. Based on this study, it was concluded that preform quality and the extrusion pressure increase with increase of viscosity and improvement in the wettability characteristics of the lubricant.
The Determination of the Best" Viscosity Model for Shear Thinning Fluids from Capillary Rheology Experiments"
This paper describes an algorithm used to determine a single viscosity correlation from capillary rheometer experiments. One can choose any one of seven commonly used models for shear thinning fluids. The program then determines the constants in the chosen model which best describes all of the experimental data in a statistical (i.e., least sum of squares) sense. By comparing the results from several different models, one can determine in a matter of minutes the model, which best describes the measured rheology data.
High Performance Polyethylene Resins for the Thin Wall Injection Molding Market
A new single-site catalyst and process technology has been used to produce resins for thin wall injection molding lid applications. The performance of the single-site resins is compared with conventional Ziegler-Natta resins. The single-site polyethylenes provide superior processability with less mold deposit and organoleptic concerns. Additionally, these resins possess equivalent or better stiffness and toughness versus competitor products along with an unusually high level of clarity in the final parts.
Effect of Cyclic Cooling on Power Consumption of the Injection Moulding Process
The performance of a cyclic mold cooling system has been investigated with particular emphasis on process power consumption. A highly instrumented proportional-hydraulic injection molding machine was used to produce tensile test specimens from HDPE. Mold temperature was monitored at high frequency during each cycle, as was nozzle melt pressure, temperature and power consumption. Reduced cycle times were achieved with cyclic cooling and savings in power consumption of up to 23% were recorded over conventional methods.
A Novel Microcellular Co-Injection Molding Process
This paper presents the development of a novel microcellular co-injection molding process that combines aesthetic and processing advantages of injection molding with the benefits and property attributes of microcellular plastics (MCPs). While eliminating the swirling patterns seen on surface of microcellular plastic parts, this process is capable of producing lightweight parts with lower energy requirements, better dimensional stability, reduced sink marks, and desirable microcellular structure with fine cells and high cell density.
Real-Time, Non-Intrusive and Non-Destructive Ultrasonic Monitoring of Injection and Co-Injection Molding Processes
Integrated ultrasonic sensors directly coated onto mold inserts of a molding machine together with rugged ultrasonic system are used for real- time, non- intrusive and non- destructive monitoring of injection and co- injection molding processes. Monitoring of flow front arrival, flow speed, filling completion, solidification, part detachment and thickness of skin and core inside the mold has been demonstrated.
In-Line Activation with Atmospheric-Plasma Makes a Strong Bond in Multi-Component Injection Moulding
In-line-activation of polymer surfaces by atmospheric-pressure plasma-treatment directly in the injection mould enables positive-joint composites to be made from polymer combinations that were hitherto unable to adhere to each other, significantly improves adhesion of compatible combinations and can be easily integrated into the process chain. The paper presents the technology, its advantages, and shows results for new compatible material-combinations.
Co-Injection Molding in Metal Injection Molding
Metal Injection Molding (MIM) is a process to manufacture metal parts, combining powder metallurgy with plastic injection molding. With MIM process, it is possible to produce highly functional composite metal structures by insert molding, co-injection or double injection molding. In this study, co-injection molding was applied to manufacture composite component of dissimilar metals. The effect of injection speed on flow behavior of dissimilar metal powder was experimentally investigated.
Localized Material Effects Associated with Flow Control during Multi-Cavity Injection Molding Processes
This paper describes a numerical simulation based study of a new injection molding concept focused on locally controlling the filling of multi-cavity molds in real time. The concept is applicable to all runner system types and involves the utilization of controllable mechanical valves. Several types of valve designs in cold runners were modeled and the effects of various control scenarios on localized material conditions throughout the mold are presented.
Optimization of Injection Molding Process Parameters by the Combining ANN/GA method
The process conditions in injection molding have important influence on the part quality, so how to get the optimum process parameters is the key to improving the part quality. In this paper, a combining ANN/GA method is proposed to optimize the process parameters so as to improve the part quality. Application of the method in an industrial part indicates it is an effective tool for the process optimization of injection molding.
Velocity Analysis in Recovery Process for Reciprocating-Screw of Injection Molding
A reciprocating-screw of injection molding not only rotates like extrusion screw but also moves axially during recovery process. A velocity analysis establishes a relationship among melt velocity to barrel, melt velocity to screw, and screw velocity to barrel in axial direction. As the application of this velocity analysis a liquid agent dosing is discussed in this paper.
Performance of a Distributive Melt-Mixing Screw with an Advanced Mixing Tip
The DM2 high-performance screw combined with an Eagle mixer on the tip can be used in injection molding processes to decrease cycle times, reduce scrap rates, and provide high levels of mixing for coloring natural resins using color concentrates. The screw combination works by increasing the melting capacity and eliminating solid polymer particles from the discharge. The performance of this screw combination is presented along with the performance of a conventional screw.
Approximate Maximum Flow Length Ratio of Plastic Parts
In this paper, an efficient algorithm is proposed for calculating the approximate maximum flow length ratio of parts. The method mainly uses approximate shortest path algorithm on a weighted triangle mesh model to calculate flow length ratio of part. Although the algorithm is an approximation, it has high approximation accuracy and is numerically robust. An applications of this algorithm is discussed.
Use of In-Line Viscosity Control Method to Stabilise Part Quality during Regrind Variation
In the injection molding process, variation of material viscosity through a change in the material behaviour and environment may lead to production problems such as poor process control and defective parts. To correct these problems, an in-line viscosity control method has been developed for use in the production environment. The method utilises melt temperature to control the material's viscosity, ensuring that its response remains consistent. The method and the quality improvements obtained are presented in this paper.
Minimizing Warpage of Injection Molded Part by Systematical Simulation Analysis
A systematic simulation approach was used for minimizing warpage of an injection molded part. An example was given to illustrate the approach. The complete simulation analysis was able to reproduce the existing warpage for the sample part. Then it was used to optimize the process conditions, modify the runner system design, and check the cooling line layout design for minimizing the part warp. The analysis final results showed very good filling balance, lower injection pressure, fairly uniform cooling and lower warpage for the part.
Prediction of Core Shift Effects Using Mold Filling Simulation
Uneven distribution of melt flow around a core pin during injection molding can result in core shift. In turn core shift affects the melt flow pattern as it changes the boundary conditions of the flow. Prediction of core shift is important because it causes variations in wall thickness of thin-walled parts.In the article we present algorithms and results of mold filling simulations that take into account the core shift effects.
Visualization and Analytical Simulation of a Viscous Fluid Flow in a Screw Channel
Injected1 long fibre reinforced thermoplastics are widespread in automotive industry, but plastication and fibre breakage occurring are not well-known. We performed original 3D flow visualisation in a transparent screw-barrel unit.Analytical simulations from simplified flow models in screw channels, on metering zone (molten polymer), were used. Particle trajectories obtained by both approaches are compared.
Numerical Simulation of the Filling Stage in the Micro-Injection Molding Process
In this work, a three-dimensional finite element flow analysis code is used to simulate the micro-injection molding problems. Non-Newtonian, non-isothermal flow solutions are obtained by solving the momentum, mass and energy equations. The interface between the polymer and the air is tracked by solving an additional transport equation. Solutions are shown for a mold containing two rectangular cavities, the parts presenting thin ribs of 150?m thickness. The numerical solutions are compared with experimental results.
Increasing Quality by Online Control of the Cavity Pressure
An online cavity pressure controller for injection molding has been developed. During the filling phase a constant gradient of the cavity pressure is realized, in the holding pressure phase the cavity pressure is calculated with a pvT-optimization. Controlling the cavity pressure results in higher quality and constant molded part properties.
Ejection of Tubular Polypropylene Mouldings: The Influence of Processing and the Molecular Weight
Polypropylene is used for the production of deep moldings of tubular shape. Predicting the required ejection force is a design issue for this type of moldings.Two polypropylenes of different molecular weights (melt flow indices) were used for producing tubular moldings in an instrumented mould. Experimental data on force and shrinkage was gathered and related for varying processing conditions.
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