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
Validation of On-Line Molding Process Simulation
Plastics injection molding has been limited by the lack of observability and controllability, such that it has not been possible to know or control flow rates and pressures at multiple locations in a mold. Using cavity pressure transducers and faster than real time process simulation, the described system provides estimates of the flow rates, part weight, melt temperature, and apparent viscosity before the mold opens and the parts are ejected. Validation results for part weight are provided for a two-cavity family mold with a valve-gated hot runner system.
Derivation of Process Windows
Selection of set-points is of vital importance to the quality and economics of manufacturing processes. However, most recipes are developed from recursive trial and error interpreted via prior human experience. A new analytical procedure based on the Extensive Simplex Method is presented that derives the global process window for an arbitrary number of process parameters and quality specifications that requires minimal process experimentation. The methods are applied to an injection molded component with width, length, and flash specifications and shown to provide excellent results.
Concept Design of a Wireless Pressure, Temperature, and Flow Rate Sensor for Injection Molding
A new concept design for a self-energizing, wireless sensor is presented. The sensor extracts energy from the polymer melt and transmits discrete acoustic signals whose timing indicates a pressure change and whose frequency indicates the melt temperature. A receiving system outside the mold receives the transmitted signals and reconstructs the melt pressures and temperatures. It then utilizes mapping and simulation techniques to estimate the pressure, temperature, and flow rates in the entire mold in real time.
A Review of In-Mold Pressure and Temperature Instrumentation
A survey of commercially available and broadly used pressure and temperature sensors for injection molding is presented. The various pressure and temperature sensing means are reviewed along with the geometry and performance of common transducers. Usage and trade-offs in sensor design and selection is discussed.
Modeling of the Film Blowing Process for High Stalk Bubbles
A simple equation with only a few physical parameters for the description of the high stalk bubbles has been derived from variational principles. The proposed equation was used in modeling of the film blowing process and a very good agreement between measured and simulated data was found.
Investigation of Zig-Zag Type of Interfacial Instabilities in Coextrusion
Modified Leonov model has been used for the viscoelastic stress calculation in the flat multi-manifold coextrusion die used for LDPE film casting process. It has been shown that specific type of high stress area occurs around the interface at the end of the converging section. This total stress has been found to be nonmonotonic along the interface and related for the onset of zig-zag type of interfacial instabilities when the total stress achieved 200 kPa.
Effect of Impulse Heat Sealing Process Parameters on Bond Strength of Low Density Polyethylene Films
In this paper, process and film parameters affecting the peel strength of impulse heat sealed thermoplastic polymeric films are investigated. In particular, the roles of film thickness and duration/temperature of application of impulse heat sealing tool are investigated for low density polyethylene. The data obtained are particularly useful in flexible packaging and film sealed container applications.
Plastic Piece Stress Analysis Using Simulation Software
The objective of this work was to evaluate mechanical properties of a cellular phone. Evaluation was made employing two commercial simulation programs. Acting bonds and external forces to simulate the phone opening action were determined. Programs used were capable of modeling static loads for the stress analysis by finite element mesh creation. Maximum wall shear stress and residual stresses showed maximum values in the gate area, in smaller thickness sections.
Finite Element Analysis of Living Hinge Behavior
The study investigates the high deformation and resulting high strains occurring during the flex of living hinge designs by putting a finite element model through the full range of motion. It investigates the ability of this technique to predict feature alignment after fully closing by comparing to actual molded parts. It investigates the feasibility of obtaining accurate simulation results from a model that undergoes high element distortion and material model at very high strains.
Visualisation and Analysis of Polyolefin Multilayer Coextrusion Flows
Flow visualisation studies were preformed to determine process parameters initiating interfacial instability in the coextrusion of polyolefin melts. Slit coextrusion visualisation cells with 30° and 90° convergent streams were studied. Studies were performed using two different extruder arrangements. Stress fields, quantified using birefringence. Concomitant velocity and layer ratios leading to wave type interfacial instability in the polyolefin melts are presented.
Electrically Conductive Immiscible Polymer Blends as Sensors for Chemicals
Sensors produced as extruded filaments based on HIPS/ABS/CB and HIPS/LLPE/CB blends were exposed to ethanol, acetone, heptane and benzene. The solubility parameters of the liquid and the blend components are important in determining the sensing level. Sensors based on proper immiscible polymer blends exhibit reproducible and recoverable electrical resistance behavior upon exposure to liquid/ drying air cycles, selectively responding to different liquids or liquid mixtures of different ratios.
Influence of Die Design on Interfacial Instabilities in Coextrusion
Fully viscoelastic FEM together with flow visualization technique are employed to quantify the effect of the die design on the wave type of interfacial instabilities in coextrusion. It has been shown experimentally that the minor channel geometry has a strong impact on the wave type of interfacial instabilities and the results can be correlated through novel criteria called as Total Stress Difference (TSN), which takes in to account the bulk change of the total stress in normal as well as tangential direction with respect to the interface.
The Warpage of FCBGA by Synthesized Analysis
The FCBGA can have the advantages of flip chip and BGA to provide the needs of high-speed networking and telecommunications systems. This study tries to predict the accumulated warpage of FCBGA throughout the sequential packaging process. Since IC device is packaged by several kinds of materials with dissimilar properties, the methodology of death-and-birth is used to simulate the existence of components at each stage. The results show similar trend with the experimental verification.
Influence of Curing Systems and Irradiation on Woodflour Filled EPDM Compounds
Rheological and mechanical behavior of EPDM rubber filled with woodflour was studied based on blend ratio and curing systems. Irradiation was also studied as an alternative crosslinking method. Results indicate that woodflour accelerates rubber vulcanization. When comparing curing systems, final overall vulcanizates properties did not deteriorate with the efficient system. Concerning irradiation, an optimum dose of 110 kGy was found, since lower doses do not promote crosslinking and higher doses tend to decrease overall properties.
The Dynamic Rheological Behaviors of PP Melt during Pulsatile Extruding Processing
A novel dynamic capillary rheometer (DCR) was designed to investigate the viscoelastic characteristic of polypropylene melt. The pulsatile flow of polymer melt could be got by parallel superposition of oscillation on steady shear flow in this novel DCR. The vibration frequency-dependent behavior of the phase angle and the shear stress vs. shear rate loops can be determined during pulsatile extruding processing. With the increase of the vibration frequency, the elastic characteristic of PP melt becomes more apparent.
3D Numerical Simulation of Flip-Chip Underfill Encapsulation
The analysis of encapsulant flow during under-fill encapsulation would be discussed in this work. With solving the melt-front positions based on 3D Finite Volume Method, we get better predictions than 2.5D simulation. For the surface effects among encapsulant, bumps and substrate, the results illustrate that the variations of contact angle influence filling time greatly. Moreover, by applying approximated parameters of dynamic contact angle model, we can simulate the influence of different processing conditions on filling time predictions.
Molding of Polycarbonate / ABS Parts for Chrome Electroplating
Electroplating PC/ABS requires the plastic be conditioned through “etching” where metal is interlocked into the part. This only occurs when the part has a butadiene-rich surface. Not achieving this condition results in costly unrecoverable plated scrap. In this study, the injection molding process effect on plating scrap was studied where it was learned that the slower the injection rate provides less plating scrap, contrary to traditional molding efficiency.
Slender Bubbles: Inertial Effects and Stability
The influence of inertia on the deformation and breakup of a slender bubble embedded in a Newtonian liquid in an axisymmetric extensional flow has been theoretically studied. The steady-state problem is governed by two dimensionless parameters: The capillary number and the Reynolds number for the external flow. The calculated stationary deformation reveals the existence of multiple solutions. A stability analysis of these results is used to distinguish between stable and unstable solutions and to establish the break-up point.
Effect of Process Aids on Interfacial Instabilities in Coextrusion
New slip model based on ‘effective continuum methods’ for the description of slip was developed and used for investigation of process aids effect on the zigzag type of interfacial instabilities in coextrusion flow.
Design of PVC Pipes for Shock Resistance
One of the major difficulty in designing extruded structures consists in understanding and managing their driving parameters like: material structure;process characteristics;their system effects; which influence the shock resistance. Thus, it is proposed to identify these relationships within the context of redesigning the PVC pipes for sewer systems.
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