SPE Library

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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Conference Proceedings

Optimization of Injection Molding Process Parameters by the Combining ANN/GA method

Changyu Shen, Lixia Wang, Qian Li, Jingbo Chen, May 2004

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

Jingyi Xu, May 2004

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

Mark A. Spalding, Jeffery A. Kuhman, Dave Larson, Jon Kuhman, H. Lee Prettyman, May 2004

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

Shen Changyu, Yu Xiaorong, Chen Jingbo, Li Qian, May 2004

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

P. Brincat, A. Bakharev, R. Speight, P. Kennedy, May 2004

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

Shijun Ni, May 2004

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

Alexander Bakharev, Zhiliang Fan, Franco Costa, Sejin Han, Xiaoshi Jin, Peter Kennedy, May 2004

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

M. Moguedet, J. Balcaen, Y. Béreaux, J.Y. Charmeau, X. Raoul, May 2004

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

Florin Ilinca, Jean-François Hétu, Abdessalem Derdouri, May 2004

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

E.h. Walter Michaeli, Juan Gruber, May 2004

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

A.J. Pontes, A.S. Pouzada, May 2004

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.

The Effects of Runner Diameter on Packing of a Plastic Part with Injection Molding

Peter C. Knepper, May 2004

This paper presents a study on the effects of runner diameter on packing. Previous studies have focused on gate effects. Injection molding simulations can often indicate that very small runners are adequate for filling, but can freeze off before the part is fully packed out. This study tests various cold runner sizes and materials in order to try and minimize the size of the runner for a given material.

The PVT Effect on Final Sintered MIM Components

Cody D. Greene, Donald F. Heaney, May 2004

Accurately predicting the linear shrinkage of metal injection molded (MIM) components for tool scale-up is commonly done by a combination of estimating shrinkage based on solids loading and prototyping. Extending published techniques from the plastic industry, pressure-volume-temperature (PVT) data and processing parameters are utilized to determine the post molding shrinkage and its effect on final sintered component dimensions. A relationship between injection molding process parameters and sintered component dimensions is presented.

Mechanical Properties of Ultra High Speed Injection Molded Parts

Hiroaki Okumura, Machiko Mizoguchi, Susumu Takashima, Satoko Baba, Shigeyuki Nagata, Hiroyuki Hamada, May 2004

The first attempt of sandwich injection molding with ultra-high speed equipment was described by using Polypropylene as the matrix material. The injection speed of core material was 1000mm/sec. The difference of core progressive behavior between low and high injection speed was recognized. Also the thickness of skin material decreased with increase of core flow length and finally it reached 150?m. The difference of mechanical properties was not significant.

Micromoulding: Process Evaluation

B. Whiteside, M.T. Martyn, P.D. Coates, May 2004

A data acquisition suite capable of monitoring a number of process dynamics at high sampling rates has been installed onto a commercial micromoulding machine. Data was collected during moulding of products of mass 25mg - 0.3mg over a range of process conditions. Results of high shear rate rheology and evaluation of possible material degredation are presented. An investigation into the repeatability of the process has been performed and the paper discusses which process parameter is most suitable as an indicator of moulding conditions which can be used in a process monitoring capacity.

Micro Molding of Polymer Cantilevers for Sensor Applications

J. Zhao, V. Samper, K. Ramesh, G. Chen, J.M.S. Yong, May 2004

In recent years there has been considerable interest in the micro molding process as the trend slanting towards miniaturization. In the present paper micro molding process studies have been carried out on the micro molding of polymer cantilevers for sensor and actuator applications. Microgrinding, EDM, and micro-EDM methods have been used for fabrication of micro cantilever tools. The effects of micro mold surface roughness and process conditions on part quality have also been studied.

Development of a Micro/Nano Injection Molding Testbed

Sung K. Lee, Charles L. Thomas, May 2004

In this work, an injection molding test bed is being developed that is designed specifically for molding micro-scale parts with nano-scale features. The device is designed to mold with sub-milliliter sample sizes and to produce arbitrarily large injection velocities and injection pressures. Initial experiments have produced 125 micron thick, 5000 micron diameter center gated disks with a nanometer scale sinusoidal surface texture. This surface texture will be used to measure shrinkage and warpage on the micro-scale using Micro-Moire.

Assessing Vibration-Assisted Injection Molding through Fatigue Lifetime Studies

Ryan M. Hydro, Raymond A. Pearson, John P. Coulter, David C. Angstadt, Rajesh Gomatam, May 2004

An investigation into fatigue lifetime behavior of polycarbonate and polystyrene materials processed by both conventional and vibration-assisted injection molding (VAIM) is underway. The goal of this investigation is to determine whether the vibration-assisted process improves the fatigue behavior. In addition to characterizing fatigue behavior, the micromechanical deformation mechanicals controlling fatigue behavior will be elucidated.

Use of Infrared Thermal Imaging to Study Mold & Part Cooling

John Bozzelli, John Lafeber, May 2004

Infrared thermal imaging has been successfully applied to numerous applications involving electrical, mechanical and building maintenance. Application studies involving plastics have been mostly successful yet our industry does not use Infrared Thermal Imaging. It has not caught on in the plastics industry. This paper presents a series of practical applications involving plastic and mold cooling troubleshooting and analysis. Infrared Thermal Imaging has evolved into a viable method for fast, accurate and economical mold and part cooling studies

Saving Time by Foam Injection Molding

E.h. Walter Michaeli, Sasan Habibi-Naini, May 2004

Foam injection molding (FIM) offers many advantages. One of them is a high potential for cooling time reduction compared to standard injection molding. This paper deals with a thorough investigation on the potential of cooling time reduction by FIM. Results will be presented and discussed in depth.