Simulation of Polymer Melt Injection Molding Filling Flow Based on an Improved SPH Method with Modified Low‐Dissipation Riemann Solver

Abstract A novel melt manipulation “RheoDrop” concept for hot runner injection molding is presented. In this concept, a controlled rotational shear is applied to a polymer melt in the hot drop to reduce its viscosity without raising the temperature. This is achieved by providing a transient rotational motion to the valve pin in the hot drop. This strategy is developed to mitigate issues associated with cold slug formation during injection molding in hot runner systems. The cold slug formation is particularly relevant for injection molding of engineering plastics such as liquid crystal polymers (LCPs) for medical and electronic applications. Analytical and experimental investigations were performed to validate the concept. The efficacy of the concept is assessed analytically utilizing a combination of two software modules, autodesk, moldflow and ansys fluent. The results confirmed that the concept was able to produce enough shear to reduce the dynamic viscosity between injection molding cycles. A prototype RheoDrop system was designed and developed and retrofitted in a four drop hot runner system mold to experimentally validate the concept. Preliminary experiments were performed utilizing acrylonitrile butadiene styrene, and parts were successfully fabricated at temperatures that are too low for traditional molding in a hot runner system.

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Evaluation of a Piezoelectric Energy Extraction Device for Cavity Pressure Sensing in Injection Molding

Dynamic Systems and Control, Volumes 1 and 2 ◽

10.1115/imece2003-42675 ◽

2003 ◽

Cited By ~ 1

Author(s):

Charles B. Theurer ◽

Li Zhang ◽

David Kazmer ◽

Robert X. Gao

Keyword(s):

Injection Molding ◽

Mechanical Strain ◽

Piezoelectric Element ◽

Polymer Melt ◽

High Energy ◽

Injection Molding Process ◽

Molding Process ◽

Transient Model ◽

Piezoelectric Energy ◽

Wide Range

This paper presents the design, analysis, and validation of a self-energized piezoelectric pressure sensor that extracts energy from the pressure differential of the polymer melt during the injection molding process. To enable a self-energized sensor design, an analytical study has been conducted to establish a quantitative relationship between the polymer melt pressure and the energy that can be extracted through a piezoelectric converter. Temperature and pressure are monitored during an injection molding cycle and the performance of the piezoelectric element is evaluated with respect to a mechanically static, electrically transient model. In addition to corroboration of the proposed model, valuable statistical information about the working temperature in the prototype sensor will prove very useful in the package design of molding cavity sensors. A linear model examining the energy conversion mechanism due to interactions between the mechanical strain and the electric field developed within the piezoelectric device is established. This model is compared to the functional prototype design to evaluate the relevance of the assumptions and accuracy. The presented design enables a new generation of self-energized sensors that can be employed for the condition monitoring of a wide range of high-energy manufacturing processes.

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Product Strength and Orientation Manipulation via Vibration-Assisted Injection Molding

Materials: Processing, Characterization and Modeling of Novel Nano-Engineered and Surface Engineered Materials ◽

10.1115/imece2002-33928 ◽

2002 ◽

Cited By ~ 1

Author(s):

David C. Angstadt ◽

John P. Coulter

Keyword(s):

Thermal Conductivity ◽

Tensile Strength ◽

Injection Molding ◽

Molecular Orientation ◽

Polymer Melt ◽

Polymer Processing ◽

Shear Yielding ◽

Processing Methods ◽

Improve Product

This investigation focuses on determining why polystyrene ASTM specimens exhibit an increase in tensile strength when processed by vibration assisted injection molding (VAIM) while polycarbonate parts do not. VAIM is one of several polymer processing methods that attempt to improve product properties via manipulation of the polymer melt. Observation of birefringence patterns in VAIM processed polystyrene samples show a significant impact on molecular orientation. The same studies were conducted on opaque polycarbonate and were unable to determine the degree of molecular orientation via birefringence measurement. It was theorized that VAIM did not produce significant orientation due to its higher thermal conductivity and stiffer backbone. It has been determined by this investigation that VAIM processing does impart significant molecular orientation in polycarbonate specimens but still does not increase its UTS. It is proposed that increased molecular orientation induced by VAIM processing inhibits crazes from growing into cracks. VAIM therefore favors polymers that fail by crazing (e.g., polystyrene) rather than those that fail by shear yielding (e.g., polycarbonate).

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Strain Analysis on Weld Zone of Tailor Welded Blanks in the Case of Welded Seam Cracking

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.154-155.355 ◽

2010 ◽

Vol 154-155 ◽

pp. 355-358

Author(s):

Qiao Sheng Hu ◽

Feng Ni ◽

Jian Ping Lin

Keyword(s):

Injection Molding ◽

Control Volume ◽

Weld Zone ◽

Strain Analysis ◽

Polymer Melt ◽

Bulk Temperature ◽

Curved Pipe ◽

Tailor Welded Blanks ◽

Fluid Behavior ◽

Welded Seam

A simulation model for the filling of a tubular cavity during water assisted injection molding is proposed. The polymer melt and water are assumed to be incompressible and to follow a Hele-Shaw fluid behavior. The finite element/finite difference/control volume methods are adopted for numerical simulation of the melt front, pressure at injection location variation, water thickness fraction and bulk temperature about a curved pipe, the simulation results have good agreement with the results presented in the former experiment. In comparison with the simulation result of gas-assisted injection molding, water assisted injection molding can give parts with thinner and more uniform walls and more rapid cooling.

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