Injection Molding of Rubber Compounds: Experimentation and Simulation

1991 ◽  
Vol 64 (2) ◽  
pp. 296-324 ◽  
Author(s):  
J. S. Deng ◽  
A. I. Isayev
Keyword(s):  
Experimental Data ◽  
Injection Molding ◽  
Induction Time ◽  
Flow Simulation ◽  
Injection Molding Process ◽  
Model Parameters ◽  
Large Sample Size ◽  
Molding Process ◽  
Rubber Compounds ◽  
Pressure Development

Abstract Results of experimental and theoretical studies of injection molding of rubber compounds have been reported. Characterizations on the rheological properties and the vulcanization kinetics of rubber compounds were carried out by means of MPT and DSC, respectively. The models were employed to fit these experimental data. An attempt has been made in extending the proposed empirical kinetic model based on DSC data to similar curing data obtained by means of the MDR technique. The heat-transfer effect due to the large sample size used in MDR measurements has been found to have a small effect on the kinetic data. Due to the different principle of state-of-cure measurements in MDR and DSC, the model parameters of curing kinetics have been found to be different in these measurements. A two-dimensional flow simulation of generalized Newtonian fluids based on both finite-difference and finite-element methods has been performed. The pressure development at various positions along the flow path during the filling stage of the molds was obtained experimentally for various injection speeds. The predicted results on pressure development during cavity filling showed qualitative agreement with the experimental data. Possible reasons for the observed discrepancy in pressure traces are: neglect of local extra pressure losses (in the juncture sections), compressibility of rubber compounds, leakage (back-flow) of material during injection, and voids formation in the injection chamber. The study on the vulcanization behavior of rubber compounds during injection molding process has also been done. The proposed empirical kinetic and induction time models were able to satisfactorily predict the cure levels of molded rubber products. At the same time, the results predicted by employing nth order kinetics were found to be unsatisfactory. The contribution of nonisothermal induction time in calculating cure levels of the molded rubber products was found to be significant. The mechanical properties and anisotropy have been investigated for two rubber compounds. It is suggested that there exists a mold temperature at which the properties and cycle times are optimal, and the filler type shows a significant effect on the tensile modulus. The rubber moldings were found to be highly anisotropic in mechanical behaviors. The anisotropy could be reduced significantly at high injection speed due to the faster stress-relaxation process.

An Intelligent Optimization System for PIM Process

2019 ◽  
Vol 814 ◽  
pp. 203-210
Author(s):  
Wen Chin Chen ◽  
Tai Hao Chen ◽  
Ding Tsair Chang ◽  
Manh Hung Nguyen
Keyword(s):  
Experimental Data ◽  
Injection Molding ◽  
Taguchi Method ◽  
Injection Molding Process ◽  
Optimal Process ◽  
Molding Process ◽  
Training Time ◽  
Intelligent Optimization ◽  
Optimization System ◽  
Modified Pso

This study proposes an intelligent optimization system based on the Taguchi method, back-propagation neural network (BPNN), multilayer perceptron (MLP) and modified PSO-GA to find optimal process parameters in plastic injection molding (PIM). Firstly, the Taguchi method is used to determine the initial combination of parameter settings by calculating the signal-to-noise (S/N) ratios from the experimental data. Significant factors are determined using analysis of variance (ANOVA). The S/N ratio predictors (BPNNS/N) and quality predictors (BPNNQ) are constructed using BPNN with the experimental data. In addition, a modified PSO-GA algorithm in conjunction with MLP is used to find initial weights of BPNN and to reduce the training time of BPNN. In the first stage optimization, the S/N ratio predictors are coupled with GA to reduce the variations of the manufacturing process. In the second stage optimization, The combination of S/N ratio predictors and quality predictors with modified PSO-GA is empoyed to search for the optimal parameters. Finally, three confirmation experiments are performed to assess the effectiveness of these approaches. The experimental results show that the proposed system can create the best performance, and optimal process parameter settings which not only enhance the stability in the whole injection molding process but also effectively improve the PIM product quality. Furthermore, experiences of the novel hybrid optimization system can be transferred into the intelligent PIM machines for the coming up internet of things (IoT) and big data environment.

GRANULAR FLOW SIMULATION FOR METAL INJECTION MOLDING PROCESS

1993 ◽  
Vol 07 (09n10) ◽  
pp. 2047-2056 ◽  
Author(s):  
TAKASHI IWAI ◽  
TATSUHIKO AIZAWA ◽  
JUNJI KIHARA
Keyword(s):  
Injection Molding ◽  
Distinct Element ◽  
Constitutive Relations ◽  
Flow Simulation ◽  
Metal Injection Molding ◽  
Injection Molding Process ◽  
Molding Process ◽  
Polymer Medium ◽  
Powder Particles ◽  
Complex Fluid

Metal Injection Molding treats the complex fluid which consists of thermoplastic tic polymer medium and dense metallic powder suspensions to improve flowability and formability. To understand its fundamental mechanical behavior, it is important to consider powder structures and mechanics precisely. For the analysis of this process, a new granular model is proposed, which is based on the Distinct. Element Method. Each element in this method is constituted by combining a metal powder with a binder (polymer) shell surrounding it. Both elasticity and viscosity for powder particles and binders are only considered in this mixture model as the constitutive relations. Several numerical results have demonstrated the effectiveness and validity of our developed granular modeling to deal with the various phenomena appearing in MIM process.

scholarly journals An Assessment of Thermoset Injection Molding for Thin-Walled Conformal Encapsulation of Board-Level Electronic Packages

2019 ◽  
Vol 3 (1) ◽  
pp. 18 ◽  
Author(s):  
Romit Kulkarni ◽  
Peter Wappler ◽  
Mahdi Soltani ◽  
Mehmet Haybat ◽  
Thomas Guenther ◽  
...  
Keyword(s):  
Injection Molding ◽  
Manufacturing Industry ◽  
Mechanical Stability ◽  
Flow Simulation ◽  
Dust Particles ◽  
Injection Molding Process ◽  
Market Demand ◽  
Molding Process ◽  
Thin Walled ◽  
Board Level

An ever-growing market demand for board (second) level packages (e.g., embedded systems, system-on-a-chip, etc.) poses newer challenges for its manufacturing industry in terms of competitive pricing, higher reliability, and overall dimensions. Such packages are encapsulated for various reasons including thermal management, protection from environmental conditions and dust particles, and enhancing the mechanical stability. In the due course of reducing overall sizes and material saving, an encapsulation as thin as possible imposes its own significance. Such a thin-walled conformal encapsulation serves as an added advantage by reducing the thermo-mechanical stresses occurring due to thermal-cyclic loading, compared to block-sized or thicker encapsulations. This paper assesses the encapsulation process of a board-level package by means of thermoset injection molding. Various aspects reviewed in this paper include the conception of a demonstrator, investigation of the flow simulation of the injection molding process, execution of molding trials with different encapsulation thicknesses, and characterization of the packages. The process shows a high dependence on the substrate properties, injection molding process parameters, device mounting tolerances, and device geometry tolerances. Nevertheless, the thermoset injection molding process is suitable for the encapsulation of board-level packages limiting itself only with respect to the thickness of the encapsulation material, which depends on other external aforementioned factors.

scholarly journals Estimation of Injection Molding Process for a Thin Fresnel lens By Plastic Flow Simulation

2019 ◽  
Vol 8 (10) ◽  
pp. 3276-3282
Keyword(s):  
Injection Molding ◽  
Plastic Flow ◽  
Flow Analysis ◽  
Flow Simulation ◽  
Fresnel Lens ◽  
Injection Molding Process ◽  
Molding Process ◽  
Manufacturing Defects ◽  
Simulation Results ◽  
Plastic Parts

This paper is based on the plastic flow simulation of a thin Fresnel lens to estimate the injection molding process. Nowadays Fresnel lenses are made of transparent plastics materials instead of silica-based glass to reduce handling and processing cost. For mass manufacturing of plastic parts, the injection molding process is best suited. Thus in this study plastic flow analysis of a thin Fresnel lens is carried for the evaluation of injection molding process. Plastic flow analysis helps in estimating how molten plastic will flow during the process Plastic flow analysis is also very helpful in evaluating the manufacturing defects such as air traps and weld lines without real-time experimentation. The simulation results evaluate the values of the parameters such as fill time, filing pressure, pack pressure, etc. Also, the manufacturing defects observed by the simulation results are reasonable and met the design requirement.

Viscoelastic Simulation of Flow of Rubber Compounds

1989 ◽  
Vol 62 (5) ◽  
pp. 939-956 ◽  
Author(s):  
M. Sobhanie ◽  
A. I. Isayev
Keyword(s):  
Injection Molding ◽  
Control Volume ◽  
Numerical Technique ◽  
Circular Disk ◽  
Temperature Fields ◽  
Planar Geometry ◽  
Injection Molding Process ◽  
Normal Stresses ◽  
Molding Process ◽  
Rubber Compounds

Abstract A hybrid scheme has been developed for numerical simulation of a nonisothermal viscoelastic flow in an arbitrary planar geometry of uniform thickness during extrusion and injection molding. This formulation is based on the control-volume finite-element method for solution of the continuity and momentum equations and finite difference method for solution of the energy equation. Application of this numerical technique for simulation of an extrusion and injection molding process was performed in a slit die and a quarter of a circular disk cavity, respectively. Development of pressures, shear and normal stresses, velocities, and temperature fields were calculated during nonisothermal flow of the rubber compound. Furthermore, the relaxation of stresses was calculated after cessation of the flow. The location of the meltfront was predicted during the cavity filling process. The contribution of normal stresses was studied by comparing results following from the viscoelastic and inelastic simulations.

Processability Testing of Injection Molding Rubber Compounds

1984 ◽  
Vol 57 (4) ◽  
pp. 826-842 ◽  
Author(s):  
John A. Sezna ◽  
P. J. DiMauro
Keyword(s):  
Injection Molding ◽  
Injection Pressure ◽  
Mold Temperature ◽  
Injection Molding Process ◽  
Capillary Rheometer ◽  
Excellent Correlation ◽  
Molding Process ◽  
Rubber Compounds ◽  
Using Data ◽  
And Control

Abstract A simple model of the injection molding process has been constructed using data from a capillary rheometer (MPT) and the Oscillating Disk Rheometer (ODR). For an NR and an SBR compound, the model had an excellent correlation with injection molding trials. The model successfully predicted the effects of adjusting injection pressure, mold temperature, and barrel temperature on injection times and scorch conditions. Such a model enables an injection molder to predict the effect of adjusting molding conditions, optimize his process for a given mold and compound, and control processability of his compounds batch-to-batch.

Die Pressure Losses During Injection Molding of Rubber Mixes

2009 ◽  
Vol 82 (1) ◽  
pp. 62-93 ◽  
Author(s):  
A. Arrillaga ◽  
A. M. Zaldua ◽  
R. M. Atxurra ◽  
A. S. Farid ◽  
A. S. Farid
Keyword(s):  
Injection Molding ◽  
Pressure Control ◽  
Mold Temperature ◽  
Injection Molding Process ◽  
Process Conditions ◽  
Molding Process ◽  
Pressure Losses ◽  
Pressure Decay ◽  
Rubber Compounds ◽  
Ram Speed

Abstract In order to fill the mold in a rubber injection molding process, it is necessary to inject the material into the closed mold. Rubber is usually injected under ram speed control, but it can be also injected under pressure control. In the present study, we have recorded the signals of pressure at three points during the filling of a spiral shape part. The behaviors of two rubber compounds have been studied using a variety of combinations of process conditions (including mold temperature, mass temperature, ram speed and injection molding with and without pressure holding stage). In all conditions, the transducer located in proximity to the gate exhibits pressure decay at the last stage of mold filling. Initial CAE simulations have been carried out using Moldflow software to check the capability of this sort of software to calculate pressure decay during the filling stage.

Filling Behavior of Polymer Material into Sub-^|^mu;m Structure in Injection Molding Process

2013 ◽  
Vol 133 (4) ◽  
pp. 105-111
Author(s):  
Chisato Yoshimura ◽  
Hiroyuki Hosokawa ◽  
Koji Shimojima ◽  
Fumihiro Itoigawa
Keyword(s):  
Injection Molding ◽  
Polymer Material ◽  
Injection Molding Process ◽  
Molding Process
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