Mold Filling Analysis in Vacuum Infusion Molding Process Based on a High-Permeable Medium

The objective of this paper is to understand the flow mechanism through visualization experiments and discuss theinfluence of process parameters on mold filling process. A 2D leakage flow model is developed to simulate the moldingprocess, and the simulation results show good agreement with experiments.

Vacuum Infusion Molding Process Part 1:VIMP Based on a High-Permeable Medium

The visualization experiments were carried out to investigate the permeability of the high permeable medium (HPM) and the roles of the peel ply and the HPM in the mold filling.The influence of process parameters on mold filling is discussed.Furthermore,the whole vacuum infusion molding process (VIMP) procedure is introduced in detail taking the manufacture of a model boat for example.

Research on the Forming Mechanism of Micro/Nano Features during the Cast Molding Process

Cast molding process has provided a reliable, simple and cost-effective way to fabricate micro structures since decades ago. In order to obtain structures with fine, dense and deep nano-size features by cast molding, it is necessary to study the forming mechanism in the process. In this paper, based on major steps of cast molding, filling models of liquid are established and solved; and the forming mechanism of liquid is revealed. Moreover, the scale effect between the liquid and the cavity on the filling velocity of liquid is studied.It is also interesting to find out that the wettability of liquid on the cavity may be changed from wetting to dewetting depends on the pressure difference. Finally, we experimentally verify some of our modeling results on the flowing and filling state of the liquid during the cast molding process.

Vacuum Infusion Molding Process (Part 2 VIMP Based on Grooves)

The optimal parameters for flow grooves and supply grooves were determined by a series of experiments,and the influences of various molding conditions on the mold filling process were analyzed.Furthermore,the whole VIMP procedure based on grooves was introduced in detail taking the manufacture of a sandwich panel as an example.

Recent advancements in optical microstructure fabrication through glass molding process

Optical microstructures are increasingly applied in several fields, such as optical systems, precision measurement, and microfluid chips. Microstructures include microgrooves, microprisms, and microlenses. This paper presents an overview of optical microstructure fabrication through glass molding and highlights the applications of optical microstructures in mold fabrication and glass molding. The glass-mold interface friction and adhesion are also discussed. Moreover, the latest advance- ments in glass molding technologies are detailed, including new mold materials and their fabrication methods, viscoelastic constitutive modeling of glass, and micro- structure molding process, as well as ultrasonic vibration- assisted molding technology.

Multi-objective process parameter optimization for energy saving in injection molding process

This paper deals with a multi-objective parameter optimization framework for energy saving in injection molding process.It combines an experimental design by Taguchi's method,a process analysis by analysis of variance(ANOVA),a process modeling algorithm by artificial neural network(ANN),and a multi-objective parameter optimization algorithm by genetic algorithm(GA)-based lexicographic method.Local and global Pareto analyses show the trade-off between product quality and energy consumption.The implementation of the proposed framework can reduce the energy consumption significantly in laboratory scale tests,and at the same time,the product quality can meet the pre-determined requirements.

High-temperature friction behavior of amorphous carbon coating in glass molding process

In the glass molding process,the sticking reaction and fatigue wear between the glass and mold hinder the service life and functional application of the mold at the elevated temperature.To improve the chemical inertness and anti-friction properties of the mold,an amorphous carbon coating was synthesized on the tungsten carbide-cobalt(WC–8Co)substrate by magnetron sputtering.The friction behavior between the glass and carbon coating has a significant influence on the functional protection and service life of the mold.Therefore,the glass ring compression tests were conducted to measure the friction coefficient and friction force of the contact interface between the glass and amorphous carbon coating at the high temperature.Meanwhile,the detailed characterization of the amorphous carbon coating was performed to study the microstructure evolution and surface topography of the amorphous carbon coating during glass molding process by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Ramon spectroscopy,and atomic force microscope(AFM).The results showed that the amorphous carbon coating exhibited excellent thermal stability,but weak shear friction strength.The friction coefficient between the glass and coating depended on the temperature.Besides,the service life of the coating was governed by the friction force of the contact interface,processing conditions,and composition diffusion.This work provides a better understanding of the application of carbon coatings in the glass molding.

Preparation Process,Pharmacological Activity and Molecular Mechanism of Valepotriate

In recent years,with the continuous development of the medicinal value of valepotriate and the great attention of scholars.The traditional extraction and purification process can no longer meet the current market standards and needs.The modern technology of valepotriate is of great significance to its application and development.This paper reviews the extraction and purification process,molding process and pharmacological activity of valepotriate,providing a theoretical basis for the research and application of valepotriate.

Rheological Behaviors and Processing Windows of Low Viscosity Epoxy Resin for VIMP

The chemorheological behaviors of a low viscosity epoxy resin system （Huntsman 1564/3486） for vacuum infusion moulding process （VIMP） were studied with viscosity experiments.The dual-Arrhenius rheological model and the engineering viscosity model were established and compared with the experimental data.The result showed that the viscosity in the earlier stage calculated by dual-Arrhenius model were smaller than the experimental data,while the data calculated by the engineering model were larger.Combining the two models together can predict the rheological behaviors of the resin system in a more credible manner.The processing windows of the resin system for VIMP were determined based on the two models.The optimum processing temperature is 30-45 ℃.

Preparation of the Preform of Pure Carbon Reaction Bonded Silicon Carbide by In-situ Consolidation Molding Method

A new kind of in-situ ceramic consolidation molding process was investigated on the basis of the characteristics of starch swelling in water and gelatinizing when heated. The SiC ceramic suspension containing about 50vol% solids loading and about 3wt% starch can be cast and molded into various complex-shape SiC ceramic parts in a water-thermostat. The dry shrinkage of the green body was less than 1.0% when the solid volume fraction of SiC suspension was up to 52.5%. The density and pore size were homogeneously distributed inside the biscuits. Soaked with melt silicon in a vacuum arc furnace, the biscuits were turn into SiC ceramic materials with homogeneous structure and high performances.

NUMERICAL SIMULATION OF CASTING'S MOLD FILLING PROCESS

Numerical simulation of casting＇s mold filling process is the main and the most important aspect of the foundry CAE technology. But it is time-consuming; it may take dozens of hours or several days. While with the development of computer hardware, numerical simulation of casting＇ s mold filling process has made rapid progress. The simulation results, therefore, have become more and more practical. This study tries to find some clues of the computational time of mold filling process. Firstly, this paper introduces mathematic model and the basic route of numerical simulation of casting＇s mold filling process. Then the computational time of mold filling process has been carefully studied, and some new and useful results have been gained from the study of the computational time. Finally, this paper has given some real applications of numerical simulation of casting＇s mold filling process.

Study on Numerical Simulation of Mold Filling and Heat Transfer in Die Casting Process

A 3-D mathematical model considering turbulence phenomena has been established based on a computational fluid dynamics technique, so called 3-D SOLA-VOF (Solution Algorithm-Volume of Fluid), to simulate the fluid flow of mold filling process of die casting. In addition, the mathematical model for simulating the heat transfer in die casting process has also been established. The computation program has been developed by the authors with the finite difference method (FDM) recently. As verification, the mold filling process of a S-shaped die casting has been simulated and the simulation results coincide with that of the benchmark test. Finally, as a practical application, the gating design of a motorcycle component was modified by the mold filling simulation and the dies design of another motorcycle component was optimized by the heat transfer simulation. All the optimized designs were verified by the production practice.

Characteristics and influence factors of mold filling process in permanent mold with a slot gating system

The main problems caused by improper gating are entrained aluminum oxide films and entrapped gas.In this study,the slot gating system is employed to improve mold filling behavior and therefore,to improve the quality of aluminum castings produced in permanent molds.An equipment as well as operation procedures for real-time X-ray radiography of molten aluminum flowing into permanent molds have been developed.Graphite molds transparent to X-rays are utilized which make it possible to observe the flow pattern through a number of vertically oriented gating systems.The investigation discovers that there are many influencing factors on the mold filling process.This paper focuses its research on some of the factors,such as the dimensions of the vertical riser and slot thickness,as well as roughness of the coating layer.The results indicate that molten metal can smoothly fill into casting cavity with a proper slot gating system.A bigger vertical riser,proper slot thickness and rougher coating can provide not only a better mold filling pattern,but also hot melt into the top of the cavity.A proper temperature gradient is obtainable,higher at the bottom and lower at the top of the casting cavity,which is in favor of feeding during casting solidification.

New numerical algorithm of gas-liquid two-phase flow considering characteristics of liquid metal during mold filling

A new program is developed for gas-liquid two-phase mold filling simulation in casting. The gas fluid, the superheated liquid metal and the liquid metal containing solid grains are assumed to be governed by Navier-Stokes equations and solved through Projection method. The Level set method is used to track the gas-liquid interface boundary. In order to demonstrate the correctness of this new program for simulation of gas-liquid two-phase mold filling in casting, a benchmark filling experiment is simulated （this benchmark test is designed by XU and the filling process is recorded by a 16-mm film camera）. The simulated results agree very well with the experimental results, showing that this new program can be used to properly predicate the gas-liquid two-phase mold filling simulation in casting.

Selective Laser Melting Molding of Individualized Femur Implant:Design,Process,Optimization

Efective Selective Laser Melting(SLM)molding methods for femur implant design and molding can improve femur implant surgerysucess rates and enhance patients quality of life.In this study,an individualized femur implant and individualized biological fixed-typefenur implant were designed using the parametric modeling method.The implants were then directly manufactured via SLM moldingtechnology as the forming process was carefuly analyzed.The results indicate that the proposed implant allows for favorable conjunctionof the reconstructed implant model with the surrounding bone tissues under the premise of a relatively small amount of bone-cutting.Theproposed implant also shows even pore distribution,good overall connectivity,relatively high bearing capacity,favorable overlappingbetween supports,and strong inter-pore connectivity.Only a small amount of powder adheres onto the surface and can be directly usedafter simple sand blasting and polishing.The comprehensive analyses of fenur implant modeling and molding methods given in this papermay provide a sound foundation for the design and direct manufacture of individualized femur implants in the future.

Flexural Properties of Grooved Perforation Sandwich Composites

Selecting H-60 PVC foam, four-axis E-glass non-woven fabric and vinyl resin, a type of innovative reinforced sandwich composite as grooved perforation sandwich （GPS） were fabricated by VIMP. The interfacial structure between the face and core of the sandwich is innovative because of the acuminate grooves in both sides of foam core and the holes perforated along core’s height. The fabrication results show that VIMP is a high-speed and cost-effective manufacturing method. The mechanical properties of the reinforced foam core were tested. The typical flexural failure modes of sandwich specimens were observed. The flexural stiffness and ultimate bearing capacity of sandwich were studied by ordinary sandwich beam theory and finite element method.

Shape design and performance test for small wind turbine blade

Based on the 1D-blade element momentum theory (BEM) with the improved tip loss correction introduced, a new aerodynamic model of wind turbine is developed. Using one high aerodynamic performance airfoil with 18% relative thickness, one small wind turbine blade is designed and the distribution of the chord and twist angle of the blade are determined. According to the shape parameters of the blade, a method to set up the 3D model is presented by investigating the coordinate position of each section of the blade. Based on the fiber reinforced polymer (FRP) molding technology, the manufacturing process of wind turbine blade is put forward. Using fiber reinforced polymer, the wind turbine blades are manufactured by the mold making and layer process. A test platform and method of wind turbine output power are carried out, the output powers at different speeds of the wind turbine are obtained and discussed. The comparison between the designed and one existing wind turbine rotor is completed to show the reliability and superiority of the design and test method presented in this paper.

Diagnosis parameters of mold filling pattern for optimization of a casting system

For optimal design of a gating system,the setting of diagnosis parameters is very important.In this study,the permanent mold casting process was selected because most of the other casting processes have more complicated factors that influence the mold filling pattern compared to the permanent mold casting process,such as the surface roughness of mold,gas generation from the mold wash and binder of sand mold,and the gas permeability through a sand mold,etc.Two diagnosis parameters(flow rate difference and arrival time difference) of molten metal flow pattern in the numerical simulation are suggested for design of an optimum casting system with a permanent mold.The results show that the arrival time difference can be used as one important diagnosis parameter of the complexity of the runner system and its usefulness has been verified via making aluminum parts using permanent mold casting(Fig.9).

Review of small aspheric glass lens molding technologies

Aspheric lens can eliminate spherical aberra- tions, coma, astigmatism, field distortions, and other adverse factors. This type of lens can also reduce the loss of light energy and obtain high-quality images and optical characteristics. The demand for aspheric lens has increased in recent years because of its advantageous use in the electronics industry, particularly for compact, portable devices and high-performance products. As an advanced manufacturing technology, the glass lens molding process has been recognized as a low-cost and high-efficiency manufacturing technology for machining small-diameter aspheric lens for industrial production. However, the residual stress and profile deviation of the glass lens are greatly affected by various key technologies for glass lens molding, including glass and mold-die material forming, mold-die machining, and lens molding. These key technical factors, which affect the quality of the glass lens molding process, are systematically discussed and reviewed to solve the existing technical bottlenecks and problems, as well as to predict the potential applicability of glass lens molding in the future.