Runner System Research Articles

A Strategy for Problem Solving of Filling Imbalance in Geometrically Balanced Injection Molds.

Simulation and experimental studies were performed on filling imbalance in geometrically balanced injection molds. An original strategy for problem solving was developed to optimize the imbalance phenomenon. The phenomenon was studied both by simulation and experimentation using several different runner systems at various thermo-rheological material parameters and process operating conditions. Three optimization procedures were applied, Response Surface Methodology (RSM), Taguchi method, and Artificial Neural Networks (ANN). Operating process parameters: the injection rate, melt temperature, and mold temperature, as well as the geometry of the runner system were optimized. The imbalance of mold filling as well as the process parameters: the injection pressure, injection time, and molding temperature were optimization criteria. It was concluded that all the optimization procedures improved filling imbalance. However, the Artificial Neural Networks approach seems to be the most efficient optimization procedure, and the Brain Construction Algorithm (BSM) is proposed for problem solving of the imbalance phenomenon.

Numerical and Experimental Analysis on Runner and Gate Positioning for Magnesium Alloy Die-Casted Test Piece

High Pressure Die Casting (HPDC) is a manufacturing process producing complex and precise products by injecting molten material into mold cavity at top speed and pressure. The quality of product is highly related with mold cavity design. Casting defects due to inappropriate mold design will affect mechanical properties, surface quality and product life cycle. Optimization of runner system is essential to manufacture complex and precision product design with minimal defects. The combination of runner and gating system is investigated in this paper. This paper investigated the effect of runner and gating optimization in reducing the gas porosity inside casting by evaluating the fluid and thermal distribution behavior in experimental and Computational Fluid Dynamic (CFD). The gas porosity generated in the molten magnesium alloy is due to the turbulent flow and the inconsistency of the fluid flow to push the gas bubble away from the main casting. This paper includes an X-ray of a sample product that shows correlation between gas porosity and CFD results. Results show that localize porosity gathered at the bottom of the main casting. Based on localized porosity position, runner and gating system is modified and numerical simulation is carried out for analysis. An inspection instrument step-type test piece is taken as an investigation sample to illustrate the technique of design modifications and improvements. Process parameters considered in this paper are injection speed, injection pressure, melt temperature and mold temperature. This paper proposed new runner designs that can generate balanced velocity and temperature distribution inside mold cavity, improving the solidification process aimed for reducing casting defects.

Design optimization of gate system on high pressure die casting of AlSi13Fe alloy by means of finite element simulations

The diecasting modern industries are moving towards the proof-of-concept methods based on finite element simulation (FEM), abandoning the traditional trial-and-error. Aluminum DC is a very complex process because the mold filling problems. In the new design production system approach, the FEM simulations play an important role, virtually recreating the entire casting phases. In this research, simulations were carried out using a commercial software to optimize the gates and runner’s design of a thin panel component in G-AlSi13Fe aluminum alloy actually realized in AA3004 sheet metal formed. Filling analysis was used to define the gate’s size, its correct positioning and the runner system design.

Modelling of transverse shrinkage of injection-moulded parts using experimental methods and fuzzy logic theory

The method of building a mathematical model of fuzzy structure and the set of its rules, on the basis of experimental results is presented. The developed method is illustrated on the example of modelling the relationship of the transverse shrinkage of HDPE injection-moulded part (moulding) versus the shape of the moulding and the conditions of the injection moulding process. The developed shrinkage model can be helpful at the design stage of the moulding geometry, as well as mould cavity and the runner system. Due to the fuzzy structure, the model can be easily modified and generalised into similar moulding injection processes. It is also a good starting point for the optimisation of the process, aimed at compensating the shrinkage value in the entire volume of the moulding by adjusting the pressure profile in the holding phase of moulding injection cycle.

Multi‐objective optimization of injection molding parameters, based on the Gkriging‐NSGA‐vague method

ABSTRACTPlastic production quality, manufacturing cost, and molding efficiency are three important indices for a new product development. In addition to injection molding process parameters (IMPP), runner system also has an important role in the injection molding process. In this study, the plastic production quality, manufacturing costs, and molding efficiency are considered as the optimized objectives. The design parameters include runner diameters and IMPP. The improved Kriging surrogate model (Gkriging), nondominated sorting genetic algorithm (NSGA‐II), and multicriteria fuzzy decision‐making approach (vague sets) are combined, and the Gkriging‐NSGA‐vague scheme is proposed to optimize the runner diameters and the IMPP. Firstly, the Gkriging model is established to map the correlation between design parameters and optimized objectives. Based on the Gkriging model, the NSGA‐II is combined with predictive models to obtain the Pareto‐optimal solutions. Then, the optimal Pareto‐optimal solution is obtained by the vague approach. A multicavity mold with two different plastic parts is utilized as the design case. The optimization results indicate that the Gkriging‐NSGA‐vague method is a powerful method for solving the multi‐objective optimization problems. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48659.

Influence of Gates on Quality Parameters for a Joystick Handler

The paper presents an analysis of a molding process and the structure of the mold for a joystick handler. At the simulation of the molding process are analyzed multiple variants changing the number and position of the gates, the runner system, and the number of the pockets. Several combinations of technological parameters are taking into account in establishing the set of variables, which gives the best quality for the part. With the aid of Autodesk Inventor and Moldflow software, a complete set of quality parameters are predicted.

Degating of AlSi10Cu2Fe High-Pressure Die Casting Component Using Resonance Vibration Technique

The high-pressure die casting process is meant for high volume production rate mainly used in the automotive industry. An efficient method to separate the die-cast components from the main sprue and runner system is crucial to improving the productivity of the manufacturing processes. Conventionally casting components are often separated with the use of a grinding wheel machine, trimming machine or pneumatic hammer. Often these techniques require customized machine design in trimming the cast part as each die casting gate design might be different from one another, especially when there is a change in production cast model. This may incur higher set-up cost and additional configuration time. It is unfavourable in the manufacturing production line that handles small batch high variation of casting model in the small/medium casting industry. Thus, this paper introduced an alternative degating technique with the use of a shaker machine to match the resonance of the casting component natural frequency to separate the die-cast component from the casting tree. The proposed method can overcome the drawback of the conventional method by eliminating the additional configuration time required when there is a change in different casting part design. Die casting parts employed in this study were constructed by AlSi10Cu2Fe aluminium alloy. Experimental modal analysis was performed to verify the natural frequency calculated through finite element analysis. The correlated finite element model was then employed for harmonic response analysis to compute the frequency response of input excitation location against output stress response at the gate. The results from the analysis showed that the first natural frequency mode could induce a bending mode at the gate and created the highest stress concentration at the location. Next, an experiment was carried out by exciting the first natural frequency to the casting part using a shaker machine. In the experiment, the die-cast components were able to break away within 0.31 s at its first natural frequency. This observation was found to be in agreement with the simulation results, whereby the degating time of 0.27 s was obtained. Therefore, the present study has shown that an efficient degating of casting components process can be achieved via introducing a correct mode of vibration excitation.

Simulation Studies on the Effect of Material Characteristics and Runners Layout Geometry on the Filling Imbalance in Geometrically Balanced Injection Molds.

Simulation studies were performed on filling imbalance in geometrically balanced injection molds. A special simulation procedure was applied to simulate properly the phenomenon, including inertia effects and 3D tetrahedron meshing as well as meshing of the nozzle. The phenomenon was investigated by simulation using several different runner systems at various thermo-rheological material parameters and process operating conditions. It has been observed that the Cross-WLF parameters, index flow, critical shear stress (relaxation time), and zero viscosity, as well as thermal diffusivity and heat transfer coefficient strongly affect the filling imbalance. The effect is substantially dependent on the runners’ layout geometry, as well as on the operating conditions, flow rate, and shear rate. The standard layout geometry and the corrected layout with circled element induce positive imbalance which means that inner cavities fills out faster, and it is opposite for the corrected layouts with one/two overturn elements which cause negative imbalance. Generally, for the standard layout geometry and the corrected layout with circled element, an effect of the zero shear rate viscosity η0 is positive (imbalance increases with an increase of viscosity), and an effect of the power law index n and the relaxation time λ is negative (imbalance decreases with an increase of index n and relaxation time λ). An effect of the thermal diffusivity α and heat transfer coefficient h is negative while an effect of the shear rate is positive. For the corrected layouts with one/two overturn elements, the results of simulations indicate opposite relationships. A novel optimization approach solving the filling imbalance problem and a novel concept of global modeling of injection molding process are also discussed.

Influence of dynamic temperature control on the injection molding process of plastic components

Conventional injection molding (CIM) technology has been largely used to produce plastic parts, mainly on automotive industry, due to high production ratios, constricted dimensional tolerances production, and low labor costs. Nowadays, industry has been demanding for thinner and lighter molded parts production, with better mechanical properties. Low mold temperatures (≈60ºC) are used to decrease the cycle molding time and process final costs. However, the fast cooling of parts can easily result in surface defects, such as weld lines, sink marks, or warpage. To avoid such defects and eliminate the need for secondary operations (additional operating costs), a dynamic mold heating and cooling control technology known as Rapid Heating and Cooling Molding (RHCM) can be employed. Based on RHCM, this study compared the efficiency of using heating rods, water flow, and external infrared heating systems to investigate the effect of dynamic temperature control on the injection molding process. An experimental injection mold was manufactured and used for the studies under controlled conditions to produce standard tensile and flexure specimens. The effect of process parameters, geometry of the runner system, location of the injection point, and other relevant settings was considered. From this study, new insights were obtained regarding the industrial application of RHCM as well as the degree of efficiency of different design solutions for the RHCM process.

Effect of runner design on the externally solidified crystals in vacuum die-cast Mg-3.0Nd-0.3Zn-0.6Zr alloy

The microstructure and tensile properties of a vacuum-assist high-pressure die casting (HPDC) Mg-3.0Nd-0.3Zn-0.6 Zr alloy and the effect of runner design on the externally solidified crystals (ESCs) were investigated. The microstructure of the alloy mainly comprised ESCs (large primary α-Mg grains) formed in the chamber, small primary α-Mg grains crystalized in the cavity, divorced eutectic Mg12Nd and a small amount of Mg12(NdxZn1-x) or Mg12(NdxZnyZr1-x-y) phases in the region near the shrinkage. The average ESCs grain size decreased as the distance from the center increased remarkably. The employment of ESCs collector contributed to the depression of ESCs grain size, particularly in center region. On the contrary, the grain size of small primary α-Mg has overall slightly downward trend from center to skin region, and the size difference was small. The employment of an ESCs collector effectively decreased the number and size of the ESCs, and accordingly both strength and elongation of the alloy were improved. This specially design ESCs collector improve the runner system and optimize the mold design. The elongation of the alloy approached 10%.

Analysis of Concentric Flow Mark Occurrence Phenomena in Injection-molded Samples Produced with a Hot Runner System

Molded products using a hot runner can have peculiar defects such as flow marks, gate marks, flow imbalance, and the like, caused by melt staying in the manifold channel. These phenomena have been noted, but the systematic analysis of their generation mechanisms have not been adequately shown. In this study, we focused on the generation mechanism of concentric flow marks around the gate that were observed on the surface of molded products using acrylonitrile-butadiene-styrene resin (ABS) with a side-fed type hot runner mold. An analysis was conducted using a dynamic flowing visualization method developed by the authors and a two-color molding method. A correlation between these flow patterns and flow mark generation areas was then derived. A unique stagnant behavior of the flow front was observed in the filling process, and it was thought that this caused a change in the deformation of the rubber particles in the melt during the transcription process. Results indicate a glossy unevenness on the surface. The stagnant behavior of the flow front was presumed to be a phenomenon that occurs due to the reversal of the temperature distribution between the inner and the outer layers of the cavity when the low-temperature, high-viscosity resin stagnating around the valve pin of the hot runner begins flowing into the cavity.

Rheological studies on gas-laden and long glass fiber reinforced polypropylene through an inline high pressure capillary rheometer in the injection molding process

A new inline high pressure capillary rheometer (IHCR) for measurements of viscosity at high shear rates and a wide range of materials such as long glass fiber reinforced and gas laden polypropylene is described. With this IHCR, simultaneous production of molded parts and viscosity measurements are enabled directly in the injection mold. Rheological measurements were carried out with polypropylene (PP), long glass fiber reinforced polypropylene (PP-LGF) with nitrogen (N2) as blowing agent. For validating the IHCR data, an offline capillary rheometer was used for comparative measurement. In addition, a melt flow simulation with Moldflow was carried out on the IHCR system to examine the flow of neat PP melt through the hot runner system and generate further comparative data.

Experimental and theoretical study on filling imbalance in geometrically balanced injection molds

Experimental and theoretical studies were performed on filling imbalance in geometrically balanced injection molds. Balancing the melt flow between cavities was investigated using several different runner systems at various operating conditions. Experiments indicate that injection rate, mold, and melt temperatures substantially affect the filling imbalance. It is strongly dependent on runners layouts geometry, and it has never been eliminated completely. It is most difficult to remove for high injection rates and low melt temperatures. Standard element geometry and circled element geometry cause positive imbalance which means that inner cavities fills faster, and it is opposite for one/two overturn element geometries which induce negative imbalance. A special modeling procedure is required to simulate properly the imbalance. This includes inertia effects, geometrical modeling of the nozzle where the imbalance starts, 3D tetrahedron meshing with minimum 12 layers. Simulations were consistent with experiment, however, when the imbalance increased, the discrepancies between simulation and experiment also increased. It can be stated that filling imbalance problem is still unsolved. There are serious thermo‐rheological aspects to explain for better understanding this phenomenon. Trends in modeling of injection molding are presented and new concepts solving the problem are discussed including simulation/optimization approach and a novel concept of global modeling of injection molding process. POLYM. ENG. SCI., 59:233–245, 2019. © 2018 Society of Plastics Engineers

Computer aided engineering (CAE) simulation for the design optimization of gate system on high pressure die casting (HPDC) process

Abstract A most important progress in civilization was the introduction of mass production. HPDC molds are one of main technologies for mass production. Due to the high velocity of the liquid metal, aluminum die-casting is so complex where flow momentum is critical matter in the mold filling process. Actually in complex parts, it is almost impossible to calculate the exact mold filling performance with using experimental knowledge. Due to this condition in the design procedure, the simulation is becoming more important. Simulation can make a casting system optimal and also elevate the casting quality with less experiment. The most advantage of using simulation programs is the time and cost saving of the casting layout design. The condition selection of HPDC mainly relied on the experience and expertise of an individual worker in casting industries. Systematic knowledge accumulation of die casting process was an essential matter to get optimal process conditions. In present casting industries, product development paradigm is shifting from traditional trial-and-error to proof-of-concept based on CAE -enabled simulation. Due to the high velocity of the dynamic behavior of the casting system in working conditions, aluminum die casting is a very complex process in which flow momentum is a critical issue in the mold filling process. In the new production development paradigm, CAE simulation plays an important role because it models the entire casting process and reveals the dynamic behavior of the casting system. In this research, CAE simulation was performed by using the simulation software (AnyCasting) in order to optimize the gate and runner design of an automobile part (Oil Pan_BR2E) which is well known and complicated to achieve a good casting layout. Filling analysis was used to find out the size and location of the gate and proper runner system design. By the modification of the gate and runner system and the configuration of overflows, internal porosities caused by air entrapments were predicted and reduced remarkably. With the solidification analysis, internal porosities caused by the solidification shrinkage were also predicted.

Gate Location and Injection Analysis of a Spur Gear

Injection moulding process is one of the common processes to produce plastic parts from simple to complicated parts. This paper focuses on the injection process analysis of a 25 tooth spur gear. Three runner system are proposed for the gear and each system will be analysed using Autodesk Simulation Moldflow Advisor. The most suitable design will then be chosen based on the results obtained from the simulation. The design undergoes cooling quality, sink mark, fill + pack, and warp analysis. Based on these analyses, Design 1 gave the better results compared to Design 2 and 3. From there, Design 1 runner system is chosen for the injection moulding mould which will be fabricated later in the research.

The mould for production of plastic spout cap with internal thread by injection moulding

The main aim of this article is the mould design for production of plastic spout cap with inner thread by injection moulding technology. There are described the basic steps of whole design process with respect to fulfil all technology and functionality requirements. The application of hot runner system as well as hybrid ejection system based on rotary cores and stripper plate can be considered as the main innovative features of the designed mould. The mould flow analysis was carried out for the functionality demonstration.

Quantitative prediction of oxide inclusion defects inside the casting and on the walls during cast-filling processes

Oxide inclusions are a common defect in casting production, but their formation and evolution processes are difficult to directly observe experimentally. To accurately predict these, one should calculate the formation rate of the oxide inclusion as well as its wall adhesion. Here, we propose a formation rate model that is relevant to the volume fraction of liquid metal, the temperature, and the current oxide inclusion density. A boundary condition was developed to handle the adhesion and accumulation on the wall; thus, a quantitative indicator is available to directly obtain the content of the oxide inclusion defects on different parts. We used the open source computational fluid dynamics (CFD) software OpenFOAM to predict oxide inclusion defects inside the casting and on the walls during cast-filling processes. A representative aluminum alloy-casting technology was simulated to analyze the effects of different runner systems on the oxide inclusion distributions inside casting and on the wall. The simulation results largely coincide with experimental data from the literature. A practical copper alloy-casting technology was then calculated, and the simulation results of the oxide inclusion defects are consistent with the actual casting defect distribution. This confirms the utility of the model.

Development of Mould of Rheology Test Sample via CadMould 3D-F Simulation

This research was about the development of mould for rheology test sample via simulation. The development work concerned with stages of design, simulation, analysis, and fabrication of the mould to produce good quality samples. In the design stage, three mould concepts have been prepared via Solid Works software. The simulation of injection moulding was conducted by using CadMould 3D-F software. Then, in the analysis stage, the main factor that has been studied were the cavity system, runner system and the gating system. For each design, different type of systems were applied to compare different simulation result. Through the simulation software, it was rectified that the parameter such as the number of cavities, filling time, shear stress were the main factors to contribute good rheological properties of the sample. The final result shows that Design 2 was chosen as the suitable mould due to number of cavities and good results in the analysis, as compare to other mould design. Finally, Design 2 have been fabricated and undergo fitting test to see whether the dimension had been done correctly. Based on this research findings, it was proven that to develop a mould suitable for rheology sample, the mould design selection should be made based on the type of system in simulations.

Nozzle and Hot Runner Systems for Injection Moulding Machines for the Manufacturing of Moulded Thermoplastic Composite Parts with Skin-Core Structure (Sandwich Mouldings)

Injection moulding of thermoplastic melts is based on the source flow. This principle allows for the production of mouldings in skin-core structure: the core enclosed on all sides by skin material may consist of a different or modified thermoplastic material. Generally, this method is referred to as co-injection or also sandwich injection moulding.Known applications of this method include processing of recycled material in the core and new material for the surfaces, foaming (chemically and physically) of the core material, processing of filled core material, e.g. Glass fibres and unfilled material for the surfaces. Other combined methods, e.g. with gas and water injection, are possible.The report describes the nozzles and hot runners developed by A&E Produktionstechnik Co. for the application of this method. Sample mouldings, produced and developed by customers and research cooperation partners, demonstrate the potentials and limits of the procedure in regard to the combination of different thermoplastic melts in a moulded part.

A study on the displacement analysis in the injection moulding for the camera-phone

Smartphones are currently the most popular electronic devices with high volume production activities driven by high demand and requirements for rapid turnaround time. The changes of displacement were analysed according to a variable of the gate size and runner system. The radial type and gate with large size were shown that better results in displacement. While the design and production of lenses, the key component of a camera, still need to be improved, the current technology has run into its limit with regard to trends in size and weight reduction. In this study, an injection moulding analysis was performed on plastic lenses that are widely employed for smartphone cameras. Specifically, the displacement of lenses at the time of injection moulding was studied by varying the gate size and runner system.