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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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 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
The scope of this paper is to bring to a wide audience the technology developments in the area of polymer micro/nano molding. Successfully molded products are categorized according to area of their application, and include characteristic dimensions, tolerances, weights, and materials used for each application, except when precluded by confidentiality issues. In this paper, a survey of the accomplishments and research work done in the area of polymer micro/nano molding at several universities and research institutes, and possible new applications for micromolding are presented.
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.
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Society of Plastics Engineers
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