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Optimisation of gate location with design constraints
Abstract
Historically, gating design relied heavily on the knowledge and experience of the mould designer. A number of automated gating design systems have been developed to overcome this difficulty. While it is important to consider design constraints in real applications, they are not considered in most of the aforementioned automated gating design systems. Moreover, considerable effort and expertise in both CAD and CAE operations are still required in these systems, especially when design constraints are considered. In this investigation, an automated routine is developed to handle design constraints in automated gating synthesis, taking advantages of functionality of both CAD and CAE systems. Standard deviation of filling time is used as the objective function during the gate optimisation process. Design constraints considered so far are no-gate constraints for three-plate moulded part and edge-gate constraints for two-plate moulded part.
... According to Chan et al. (2003) (Chan, Yan et al., 2003, one emergent area of research in the injection moulding field attempts to automatically generate the design of mould tool components. However, this approach has been considered feasible only for the automatic generation of particular mould components (Pandelidis and Zou, 1990;Lam and Jin, 2001;Lam, Britton et al., 2004;Lam, Zhai et al., 2004;Shen, Yu et al., 2004;Lee and Lin, 2006;Qiao, 2006). ...
... Considering the existing literature, it is possible to divide this area of research in two main topics: heatexchange system optimization (also described as cooling system optimization) (Lam, Zhai et al., 2004;Mehnen, Micheltisch et al., 2004;Li, Zhao et al., 2009) and feeding system optimization (also described as injection system optimization) (Pandelidis and Zou, 1990;Lam, Britton et al., 2004;Shen, Yu et al., 2004;Lee and Lin, 2006;Zhai and Xie, 2010). These parallel approaches are based on the authors' assumptions that production efficiency ( Park and Ahnb, 2004;; Changyu, ) and part's quality are mostly affected by the heat-exchange system design (Qiao, 2006;Li, Zhao et al., 2009), or by the contrary, by the feeding system design ( Lam and Jin, 2001). ...
The injection mold is a high precision tool responsible for the production of most plastic parts used everywhere. Its design is considered critically important for the quality of the product and efficient processing, as well as determinant for the economics of the entire injection molding process. However, typically, no formal engineering analysis is carried out during the mold design stage. In fact, traditionally, designers rely on their skills and intuition, following a set of general guidelines. This does not ensure that the final mold design is acceptable or the best option. At the same time, mold makers are now highly pressured to shorten both leading times and cost, as well as to accomplish higher levels of mold performance. For these reasons, it is imperative to adopt new methods and tools that allow for faster and higher integrated mold design. To that end, a new global approach, based on the integration of well-known quantitative techniques, such as Design for Six Sigma (DFSS), Structural Equation Modeling (SEM), Axiomatic Design (AD) and Multidisciplinary Design Optimization (MDO) is presented. Although some of these methods have been largely explored, individually or in combination with other methodologies, a quantitative integration of all aspects of design, in such a way that the whole process becomes logical and comprehensible, has not yet been considered. To that end, the DFSS methodology, through its IDOV roadmap, was adopted. It is based on the ICOV Yang and El-Haik proposal, establishing four stages for the design process: Identify, which aims to define customers' requirements/expectations; Design, where the creation of a product concept, and its system-level design, is performed; Optimization, in which all the detailed design, through product optimization, is handled; and finally, Validation, where all product design decisions are validated, in order to verify if the new designed entity indeed meets customer and other requirements. As a result, this approach tackles the design of an injection mold in a global and quantitative approach, starting with a full understanding of customer requirements and converting them into optimal mold solutions. In order to validate it, an integrated platform was developed, where all different analysis modules were inserted and optimized through an overseeing code system. The results attained highlight the great potential of the proposed framework to achieve mold design improvements, with consequent reduction of rework and time savings for the entire mold design process.
... Previous research works [1][2][3][4][5][6] on computer-aided gating design for injection moulding process provide good insight on determination of gating parameters and optimization of gating elements. Less attention was given by previous researches on determination of gating parameters for multicavity moulds. ...
Design of injection moulding dies (called moulds) is a time consuming and complex activity that requires domain knowledge and vast experience of the die-designer besides information about manufacturing resources, part geometry, number of cavities, etc. The gating design is of great importance for reducing lead time and cost of part produced and to achieve first-piece-right. The gating design encompasses several steps, involves complex computational work, and requires a number of iterations. In the present research work an attempt has been made to develop a computer-aided system, which facilitates gating design of an injection mould taking part CAD file as input. The gating parameters are calculated by taking part geometry, material and number of cavities as input. The proposed system is divided into three modules, namely Gate design, Runner design and Sprue design. To demonstrate the capabilities of proposed system, it was tried for a number of parts and the results for two industrial case study parts are presented. Proposed system is a step forward to design-manufacturing integration for injection moulding process.
... The optimal gate location is the position located gate with reducing or losing of the weld lines, shrinkage, and warpage in the final part. There are many researches on the gate location to find a best location in the mold design process such as using an optimal method of the design constraint control with an integrated tool of the computer aided design (CAD) and computer aided engineering (CAE) software to select the optimal gate location to satisfy requirement of the fill pattern and warpage [1], using a integrated method of simulated annealing and hill climbing to get the optimal gate location [2], using an automatical predict method to find the optimal gate location [3], using a genetic algorithm to find the optimal gate location in the liquid composite molding process to get the minimization of the filling pressere to achieve advantage of the uniform filling pattern [4], using a multi-objective evolutionary algorithm to optimize the gate location in liquid composite molding to minimize the filling time and prevent the resin lost [5], a solution of using modified hill-climbing algorithm to predict the optimal gate location for complicated parts [6], using a genetic algorithm to optimize gate location to minimize fill time and dry spot formation in the resin transfer molding process [7], using a branch and bound search method to find the optimal injection gate location to minimize the dry spot size and fill time [8], using an empirical search method to optimize gate location in injection molding [9] . ...
Cổng phun là vị trí dòng nhựa nóng chảy được phun trực tiếp vào lòng khuôn để tạo hình sản phẩm. Vị trí cổng phun có ảnh hưởng lớn đến khả năng điền đầy vật liệu trong lòng khuôn và chất lượng sản phẩm vì có liên quan việc đến định hướng dòng chảy trong lòng khuôn. Các khuyết tật không mong muốn có thể tạo ra trong quá trình ép phun liên quan đến việc lựa chọn vị trí cổng phun như: đường hàn, cong vênh, và hiện tượng co ngót. Do đó vị trí cổng phun là một trong những tiêu chí quan trọng nhất để điều khiển chất lượng của sản phẩm ép phun. Bài báo trình bày một phương pháp mô phỏng số hóa để tìm ra vị trí cổng phun tối ưu trong thiết kế khuôn ép nhựa để làm giảm các khuyết tật và nâng cao chất lượng sản phẩm trong quá trình ép phun các sản phẩm nhựa. Các khuyết tật trên sản phẩm nhựa được phân tích và giảm thiểu thông qua việc sử dụng công cụ mô phỏng số có sự trợ giúp của máy tính. Thông qua phương pháp này, vị trí cổng phun tối ưu được lựa chọn, các khuyết tật trên sản phẩm dễ dàng được phát hiện và kiểm soát, chất lượng sản phẩm ép phun được cải thiện.
... BBS performances were compared with existing ES and GAs showing its ability to achieve quality results with 90% less computations. A Hill Climbing algorithm was implemented taking into account constraints concerning prohibited positions for the gates; the routine was able to handle constraints that forbid the presence of gates in particular areas (no gate constraint) and on the border (edge gate constraint) [93]. ...
This study focuses on the development of a multi-objective optimisation methodology for the vacuum assisted resin transfer moulding composite processing route. Simulations of the cure and filling stages of the process have been implemented and the corresponding heat transfer and flow through porous media problems solved by means of finite element analysis. The simulations involved material sub-models to describe thermal properties, cure kinetics and viscosity evolution. A Genetic algorithm which constitutes the foundation for the development of the optimisation has been adapted, implemented and tested in terms of its effectiveness using four benchmark problems. Two methodologies suitable for multi-objective optimisation of the cure and filling stages have been
specified and successfully implemented. In the case of the curing stage the optimisation aims at finding a cure profile minimising both process time and temperature overshoot within the part. In the case of the filling stage the thermal profile during filling, gate locations and initial resin temperature are optimised to minimise filling time and final degree of cure at the end of the filling stage.
Investigations of the design landscape for both curing and filling stage have indicated the complex nature of the problems under investigation justifying the choice for using a Genetic algorithm. Application of the two methodologies showed that they are highly efficient in identifying appropriate process designs and significant improvements compared to standard conditions are feasible. In
the cure process an overshoot temperature reduction up to 75% in the case of thick component can be achieved whilst for a thin part a 60% reduction in process time can be accomplished. In the filling process a 42% filling time reduction and 14% reduction of degree of cure at the end of the filling can be achieved using the optimisation methodology. Stability analysis of the set of solutions for the curing stage has shown that different degrees of robustness are present among the individuals in the Pareto front. The optimisation methodology has also been integrated with an existing cost model that allowed consideration of process cost in the optimisation of the cure stage. The optimisation resulted in process designs that involve 500 € reduction in process cost. An inverse scheme has been developed based on the optimisation methodology aiming at combining simulation and monitoring of the filling stage for the identification of on-line permeability during an infusion. The methodology was tested using artificial data and it was demonstrated that the methodology is
able to handle levels of noise from the measurements up to 5 s per sensor without affecting the quality of the outcome.
... The resin in a heating cylinder is plasticized and injected into mold cavity through the nozzle and runner. The molten resin is then cooled and solidified, and the mold apparatus is opened so as to remove the molded product [1][2][3]. The injection molding machine was improved in terms of its structure and performance during recent decades [4,5]. ...
As a main component of injection molding machine, nozzle is used to prevent polymer melt from leaking during plasticizing and provide an access injecting polymer melt into the mold cavity during injecting process. The straight-through nozzles and shut off nozzles with hydraulic or pneumatic are adopted in the traditional injection molding machine. The paper reviews various patents on nozzles with new structures and optimized design in recent years. A spring-sliding valve type nozzle is introduced to solve melt leaking, nozzle blocking, and melt thermal decomposition. Moreover, this new type of shut off nozzle is more compacted and low-cost.
... Ali Gokce and Suresh G. Advani [6,7] proposed a cascaded optimization algorithm for simultaneous gate and vent location optimization in the presence of race tracking. Y.C. Lam, G.A. Britton and D.S. Liu [8] optimized the gate locations using the standard deviation of filling time as the objective function. Jiang Shunliang [9] proposed an approach to optimize the gate locations of RTM treating the trapping volume as penalty. ...
Vacuum infusion molding process(VIMP) is widely used for manufacturing the composite yacht hull, but the process parameters are designed by experience or lots of experiments. In this paper, the filling process of VIMP for composite yacht hull was deeply analyzed based on numerical simulation technology. Firstly, we simulated the filling process of yacht hull under different ply schemes, evaluated the manufacturability of the ply scheme based on the simulation results. Secondly, we determined the best runner layout pattern by simulating the filling process under four different runner layout patterns. Lastly, we studied the optimization method for gate locating of VIMP, established the mathematical model for optimizing the gate location and obtained the concrete form of the object function after a series of simulations, then obtained the optimal gate location result. The simulations also showed that it is inadvisable to reduce the filling time just by adding the gate quantity.
... Thus, the nozzle and the gate of mould are jointed tightly. Adding pressure behind the melted plastic to push it into a closed mould, it allows the melted plastic to solidify by cooling then opens the mould and let the ejection system push the part out [3][4][5]. Now, the single oil cylinder and the double oil cylinders both are the most common types in injection-shift devices of traditional injection molding machine [6][7][8]. The injectionshift structure is usually fixed on the stationary platen of clamping unit and the front platen of the injection seat. ...
The plasticizing and injection devices are among the main components of injection molding machines. The injection seat moves forward by injection-shift oil cylinders to joint the nozzle and the gate of mould tightly. The single oil cylinder and the double oil cylinders are adopted in the traditional injection molding machine. The paper reviews various patents of injection-shift structures through adopting new structures and new devices in recent years. A new type of the single injection-shift structure of injection molding machines is invented to solve high injection pressure, long-time holding pressure, the warpage of the nozzle and the joint fracture of shift piston rod for the traditional injection-shift device. The new type of the injection-shift structure is more compacted, reliable and especially suitable for multiple material injection molding. Moreover, when the length of injection-shift rod is shortened, the cost will be reduced.
... However, this approach has been considered feasible only for the automatic generation of particular mold components (Low 2003). Considering the existing literature, it is possible to divide this area of research into two main topics: heat-exchange system optimization (also described as cooling system optimization) (Mehnen et al. 2004;Lam et al. 2004b;Li et al. 2009) and feeding system optimization (also described as injection system optimization) (Pandelidis and Zou 1990;Lam et al. 2004a;Shen et al. 2004;Lee and Lin 2006;Mader 2003;Zhai and Xie 2010). These parallel approaches are based on the authors' assumptions that production efficiency and part quality (Park and Ahnb 2004;Ozcelik and Erzurumlu 2006;Changyu et al. 2007) are mostly affected by the heat-exchange system design (Qiao 2006;Li et al. 2009) or, on the contrary, by the feeding system design (Lam and Jin 2001). ...
The design of injection mold tools is a complex process for which market pressures demand ever-shorter development time and higher quality level. Thus, it is considered imperative to adopt new methods and tools to support the design process, in order to achieve a more effective mold design solution. Based on this assumption, a multidisciplinary framework was developed, centered on Design for Six Sigma methodology and reinforced with a set of highly valued techniques, namely: the European Customer Satisfaction, the Axiomatic Design and the Multidisciplinary Design Optimization. As a result, a platform was built to support the design of any mold tool without undercuts, which tackles the design of an injection mold as a fully integrated multidisciplinary optimization problem, oriented by customer preferences and their impositions. A set of specific analysis sub-modules is integrated through an overseeing optimization code system, responsible for the numerical simulation of the injection process. This platform was validated through the comparison with an existing mold, whose results attained highlight the great potential of the proposed framework to achieve mold design improvement. In particular, the value of mold solutions generated led to a global improvement on mold performance by 5 %.
... The key parameters of RTM tooling is to determine the position of gates and vents to ensure optimum impregnation of the preform. Several studies have aimed to define the optimal configuration, number and position of gates and vents tool [3][4][5]. These optimizations do not take into account the problem of coupling effects of manufacturing variability with the damage caused by drilling before the assembly phase. ...
A key challenge for the future is to reduce drastically the human impact on the environment. In the aeronautic field, this challenge aims at optimizing the design of the aircraft to decrease the global mass. This reduction leads to the optimization of every part constitutive of the plane. This operation is even more delicate when the used material is composite material. In this case, it is necessary to find a compromise between the strength, the mass and the manufacturing cost of the component. Due to these different kinds of design constraints it is necessary to assist engineer with decision support system to determine feasible solutions. In this paper, an approach is proposed based on the coupling of the different key characteristics of the design process and on the consideration of the failure risk of the component. The originality of this work is that the manufacturing deviations due to the RTM process are integrated in the simulation of the assembly process. Two kinds of deviations are identified: volume impregnation (injection phase of RTM process) and geometrical deviations (curing and cooling phases). The quantification of these deviations and the related failure risk calculation is based on finite element simulations (Pam RTM® and Samcef® softwares). The use of genetic algorithm allows to estimate the impact of the design choices and their consequences on the failure risk of the component. The main focus of the paper is the optimization of tool design. In the framework of decision support systems, the failure risk calculation is used for making the comparison of possible industrialization alternatives. It is proposed to apply this method on a particular part of the airplane structure: a spar unit made of carbon fiber∕epoxy composite.
... On the subject of optimal feeding subsystems, Lee and Lin (2006) used FEM, Taguchi's method and an abductive network to select the best parameters. Lam et al. (2004a) proposed an automated gate optimization routine and Shen et al. (2004) developed a modified hill-climbing algorithm in order to determine the best gate location. These examples highlight the fact that research in injection mold design optimization is underway, but generally involves only one particular aspect of the total design. ...
The design of injection molding systems for plastic parts relies heavily on experience and intuition. Recently, mold makers
have been compelled to shorten lead times, reduce costs and improve process performance due to global competition. This paper
presents a framework, based on a Multidisciplinary Design Optimization (MDO) methodology, which tackles the design of an injection
mold by integrating the structural, feeding, ejection and heat-exchange sub-systems to achieve significant improvements. To
validate it single objective optimization is presented leading to a 42% reduction in cycle time. We also perform multiple
objective optimization simultaneously minimizing cycle time, wasted material and pressure drop. Sensitivity analysis shows
a large impact of the sprue diameter (>1.5 normalized sensitivity) highlighting the importance of the feeding subsystem on
overall quality. The results show substantial improvements resulting in reduced rework and time savings for the entire mold
design process.
KeywordsInjection mold design-MDO-Global design-Cycle time
Injection molding (IM) is a versatile manufacturing process capable of rapid prototyping and mass-producing high-quality polymer parts. The present study mainly investigates the challenge of designing multiple molding gates on the complex arbitrary part surface in 3D. Currently, this problem is a challenge in mold design and engineering experience still plays an important role in designing the molding gates. To reduce the human intervention in the design process, the present study proposed a novel methodology with the following major steps: 1) using Poisson disk sampling (PDS) to preselect candidate gate locations automatically within the suitable gating region specified by designers; 2) using a space-filling initialization strategy and efficient global optimization to find the optimal gate locations. In the present setting, the molding gate design problem is formalized as a discrete optimization problem. The PDS is employed to construct the discrete solution space and EGO is used to efficiently search through a large solution space for the best design. To further promote optimization efficiency, a parallel implementation of EGO is also proposed. The effectiveness of the proposed methods is validated in two design cases. The results demonstrate the proposed EGO and Parallel EGO method is superior that the Genetic Algorithm (GA) and Surrogate Optimization (SO). Moreover, the proposed Parallel EGO converges faster than all other alternatives.
Engineering polymers have wide applications in automobile parts and its accessories are mostly produced by injection molding technique that gives good dimensional quality, durability, molding quality, and finishes. The challenging issue in injection molded products is to maintain the quality of the product in terms of dimensions, molding quality, finishes, etc. This depends on the part design, tool design, mold quality, injection molding process parameters, polymer material characteristics, etc. Experimental verification has been done with tool design, subsequently repeated number of analyses made through ‘Mold-flow Plastic Part Advisor’ to get optimized tool design considering all the injection molding process parameters. Finally, the mold is manufactured taking inputs from ‘Mold-flow Plastic Part Advisor’ and injection molded components were produced that improved the quality of the product, reduces cycle time. Thus reduces the cost of the product and the process.
تزریق پلاستیک یکی از موثر ترین فرآیندهای تولید انبوه قطعات پلاستیکی می باشد.مجموعه شیطانک کمربند ایمنی خودرو شامل سه قطعه ی پلاستیکی می باشد که وظیفه ی آن قفل کردن نوارکمربند است. قطعات این مجموعه عبارتند از1- پایه 2- بازو 3- کاسه 4- ساچمه) فلزی قفل شدن کمربند در اثر تغییر زاویه ی بازو نسببت ببه ویبعیت افقی به دلیل حرکت ساچمه در کاسه اتفاق می افتد ، لذا قطعات این مجموعه از نظر تلرانسی باید بسیار دقیق ساخته شوند و از هرگونه تغییر شکل نا خواسته در طی فرآیند تزربق جلوگیری شودقالب پایه ی مجموعه شیطانک دارای 4 حفره می باشبد ، یعنی در هر سیکل تزریق 4 قطعه تولید می شود. موقعیبت دریچه های تزریق در حفره های قالب پایه ی مجموعه شیطانک کمربند با توجه به شکل هندسی خاص و نامتقارن بودن آن باهم متفاوت است تغییر جانمایی حفره های قالب به دلیل احتیاج به کشویی میسر نیست. تفاوت در موقعیت های دریچه ی تزریق باعث ناهماهنگی در زمان پر شدن حفره ها می شود و این قضیه باعث ایجاد عیوبی مانند اعوجاب ،انقباض بیش از انتظار ، خطوط جوش و ... می شود . در این مقاله سعی براین است که بامدلینگ قطعه ی پایه ی مجموعه شیطانک کمربند درنرم افزار کتیا و باتحلیل فرایند تزریق پلاستیک آن با استفاده ازنرم افزار مولدفلو و انجام انالیز بالانس راهگاه بهترین ابعادمقاطع راهگاه را برای هماهنگ پرشدن حفره های قلب بدست اوریم همچنین حداقل اطلاعات مربوط به انتخاب دستگاه تزریق مناسب گزارش میشود.
The efficiency and accuracy of the gate optimal algorithm of injection molding could be improved by directly using the geometrical information of the fusion mesh. The objective function is defined by introducing the weighted flow length to achieve the balanced flow of the melt. To solve the objective function, the fusion mesh is translated to weighted graphic firstly under some hypotheses. And then the weighted flow length of very node could be got by using the shortest path algorithm. A new optimal methodology called as Generic-Hillclimbing (GH) was developed by combining Generic algorithm and Hillclimbing algorithm. Generic algorithm is employed to find the suboptimum gate location. Hillclimbing program used the suboptimum as the beginning point to search the optimum result. The examples which compare optimization results of the presented GH and Moldflow indicate that the presented methodology is highly efficient and accurate.
The injection molded parts warpage, represented by the geometric difference between the actual and the target part, is a permanent problem during the development of new injection molded parts. While most efforts to reduce the part warpage have resulted in optimization of the processing parameter and gate location, this study presents a method which aims to reduce the part warpage by optimization of its wall thickness distribution. This method is based on an evolutionary optimization algorithm, which interacts with the injection moulding simulation. The procedure is fully automatic and results in a STL-File for the optimized geometry of the cavity. The objective of the present study is to evaluate the efficiency of this method for a non-complex geometry.
The gating system design for a die-casting die is a non-trivial task that involves a number of steps and computations, in which many factors related to part design, material, and process need to be accounted. In case of a multi-cavity die-casting die, the non-triviality of the gating system design increases manifold. The main contribution of this article is to develop a computer-aided system for design of gating system for multi-cavity die-casting dies. The proposed system applies design knowledge and rules, accounting for various influencing factors to design gating system elements and generate their computer-aided design models in an efficient manner. To demonstrate the capabilities of the developed system, the results for an industrial case study part are presented. We expect that the proposed system would help reduce manufacturing cost and lead time, alongside bridging gaps between design and manufacturing of the die-casting process.
Reducing material waste is a major issue during new product development, especially for injection-molded parts, where the wall thickness has a strong influence on molding times and therefore on the manufacturing cost. Finding the minimum material amount for producing high-quality products is a difficult and time-consuming task using state-of-the-art computer-aided engineering CAE tools. In this study, a numerical procedure is presented to reduce the material amount required for injection-molded parts by optimizing their wall thickness distributions with respect to part quality and identifying an upper limit for the injection pressure. The closed-loop procedure consists of three main parts: (1) a mesh parameterization tool for manipulating the thickness distribution of the part, (2) a mold flow analysis for evaluating the producibility and part quality, and (3) a genetic algorithm for adjusting the design variables toward minimum material waste. The effectiveness of the procedure is demonstrated into two different industrial parts. Using the part volume as the main objective, reductions in material waste of approximately 25 to 30 % can be achieved via a slight improvement in part warpage compared to the initial design. Considering part warpage as an additional objective results in reductions in material waste of 12 to 17 %, these reductions in waste are accompanied by substantial improvements in part quality.
Warpage reduction is one of the important issues in plastic injection molding (PIM). In order to resolve this issue, there are mainly two ways to reduce warpage: One is to design the mold, and the other is to optimize the process parameters such as the mold temperature, the melt temperature, and so on. In this paper, the latter approach is employed. In particular, variable pressure profile approach is adopted for the warpage reduction. Besides the variable pressure profile, the melt temperature and the mold temperature are taken as the design variables. Also, short shot that the melt plastic is not filled into the cavity is one of the fatal defects in PIM. Unlike the literature, in this paper, the short shot is handled as the design constraint. PIM simulation is generally so costly and time consuming, and then the surrogate-based optimization technique is used. The radial basis function (RBF) network is used throughout sequential approximate optimization (SAO) procedure. Moldex3D is used for PIM simulation. In order to compare the effectiveness of the variable pressure profile, the traditional process parameter optimization considered in the literature is also carried out. Numerical results show that the variable pressure profile is one of the effective ways to warpage reduction compared to the traditional process parameter optimization.
The clamping mechanism is one of the important components of injection molding machine. The double-toggle clamping unit is applied in clamping mechanism widely. But, the existing double-toggle clamping unit is connected by cross head driven clamping mold oil cylinder. In the process of movement, especially in the open limit position or a front connecting rod close to the vertical position, the wear is very serious as it may easily cause fracture of tail platen. The paper reviews various patents of clamping unit of injection molding machine through adopting new structures in recent years. The new structure of the double-toggle clamping is presented in this paper. The new structure provided with four pull rod extending connecting lugs. Each connecting ear is provided with corresponding pull rod passes through the guide hole. The cross head can be in sliding the sleeve in the four pull rod. Compared with the traditional toggle clamping, the motion of mold platen is stable and the fracture phenomenon of tail platen can be solved. The tail platen manufacturability and reliability is improved reducing the manufacturing cost due to saving “A” frame of tail platen.
The warpage of injection-molded parts is an omnipresent problem in new product development. In this study, a method is developed to reduce the warpage by optimizing the wall thickness distribution of a part. This method is based on an iterative optimization procedure consisting of mold flow analysis, a mesh parameterization tool for geometry manipulation, and an optimization algorithm. Starting with the initial design for the mold cavity, the procedure optimizes the wall thickness distribution at user-defined area sections within prescribed tolerances. A unit-square parameterization technique is applied that uses mean-valued coordinates and a second-order polynomial thickness distribution. Three different optimization algorithms—an evolutionary algorithm, a surrogate-based response surface method, and a direct search method—are considered, and the optimization performances of these algorithms are evaluated for a warpage demonstrator and real industrial part. The results demonstrate the effectiveness of the developed procedure and plausibility of the optimized thickness distribution.
Although the layout of multicavity molds is a geometrically balanced design, when the melt flows into the runner, the shear-induced partial changes in material properties will result in intracavity imbalance. This study placed a rectangular flow restrictor within the tertiary runner of a precision optical lens mold to create melt turbulence through flow blocking. Due to polymer rheological characteristics, uniform melt temperature distribution in the runner channel could be obtained, making the temperature distribution inside the cavity more uniform, and reducing the thermal residual stress and warpage of injection molded parts. The optimal runner restrictor design is placing 5 mm away from the secondary runner centerline, making both the depth and the width of the block 3 mm. A relatively uniform melt temperature distribution with a maximum temperature difference of 1.1 °C can be achieved. Injection molds were fabricated according to the optimized restrictor design, and experimental verification was performed. The contour accuracy of a lens parallel to injection direction was improved from 10.44 to 5.03 μm. Therefore, this runner restrictor design can be applied to high-precision optical molds due to the ease of machining and the capability of improving the quality of optical lens.
Weld lines are one of the critical defects in injection molding production. They affect the strength of the plastic parts and are visually unpleasant. To address this problem, this paper proposes some strategies and methods for the formulation and implementation of an optimization procedure to minimize the defects of weld lines by minimizing their total length and by positioning them as further away as possible from, or restricting them from occurring at, the specified critical regions on the part surface. Several concepts are defined, such as the weld line relevant part qualities, types of critical regions, and constraints on the occurrence of the weld lines. Based on these, the optimization problem is modeled and a genetic algorithm (GA) based optimization procedure is proposed. The methodology can provide useful guidelines for injection molding designers in achieving the optimal part quality relevant to the weld lines. A case study is also conducted to demonstrate the effectiveness of the methodology.
This paper deals with the application of intelligent system for injection mold design. The molding system of the developed knowledge-based module for injection molds more detail is considered For this aim the known theoretical methods of gates and runners definition as well facts and rules were systematized using experts' knowledge. The calculation accuracy of gates and runners were tested by the developed knowledge-based method comparing it with practical data.
Injection moulding optimisation seeks to achieve the highest possible moulding quality under the specified constraints. To
this end, the factors (design variables) affecting the moulding quality should be adjusted, including those of process parameters,
mould design, part geometry, etc. Past work in this aspect is primarily focused on tuning the process parameters and mould
design (e.g., gate location, runner and cooling channel layout), with less attention on the part geometry, and none on them
all. To address this problem, this paper presents a PSO (particle swarm optimisation) algorithm for the optimisation of multi-class
design variables, such as the part thickness, process parameters (melt temperature, mould temperature, injection time) and
gate location. The optimisation is targeted at different aspects of moulding quality, including part warpage, weld lines,
air traps, and so on. In applying the PSO algorithm, the paper proposes a modified elite archiving method, which can expedite
the convergence speed, hence improving the efficiency of the algorithm. A computer program was developed that automates the
steps such as adjusting the part thickness, the injection moulding process parameters and the gate location, activating the
CAE software to simulate the injection moulding process, retrieving the simulation results, and evaluating the objective functions.
The whole procedure iterates a number of generations by following the search process of the algorithm. A case study was also
presented to illustrate as well as to test the proposed methodology, which was demonstrated as both effective and efficient.
A gate location is one of the most important design variables controlling the product quality of injection molding. In this
paper, the numerical simulation of injection mold filling process is combined with the design optimization method to find
the optimum gate location to achieve balanced flow. The objective function is expressed in terms of the difference between
the maximum and minimum times of boundary filling. The coordinates of gate are chosen as design variables, and a constraint
is employed to limit the clamp force lower than the reference value. The optimization problem is solved with the sequential
linear programming algorithm, and design sensitivities are evaluated via the finite difference approximation. Finally, numerical
examples are given to demonstrate the effect of proposed methods.
KeywordsInjection molding-Gate location-Optimal design-Flow balance
Family mould layout design (FMLD) is demanding and experience-dependent. It involves many sub-design tasks that determine
the cost and performance of a family mould in the early conceptual mould layout design phase. This paper conducts a comprehensive
literature review in the field of FMLD. The review ascertains that family mould cavity and runner layout design (FMCRLD) automation
and optimisation is the critical knowledge gap in FMLD, and it should be viewed as a complex combinatorial layout design optimisation
problem. The second part of this paper extends the review of the literature regarding possible computational techniques for
supporting FMCRLD automation and optimisation. The review discovers that the evolutionary design approach using genetic algorithms
reveals a new opportunity to automate and optimise such complex FMCRLD with an explorative and generative design process embodied
in a stochastic evolutionary search. However, implementation of this innovative approach is full of challenges. Further research
on this topic is urgently needed.
KeywordsFamily mould–Optimum cavity and runner layout design–Design automation–Evolutionary design
A multi-objective evolutionary algorithm is applied to the problem of optimal gate location in liquid composite moulding. The Non-dominated Sorting Genetic Algorithm-II (NSGA-II) is implemented and the efficiency of different variation operators is assessed on a benchmark problem, i.e., a mould of simple geometry. Following this, the algorithm is applied to a more complex mould geometry with the best variation operators. It is shown that the sole use of mutation proved better in the case of a complex part, whereas crossover proved helpful only for a simpler geometry.
One prominent characteristic of product design for injection-moulded parts is
that design and analysis (e.g. ¯ow simulation) go hand in hand to ensure that the design is manufacturable by the injection-moulding process. Despite the wide use of CAD and CAE systems, the two processes are still not integrated. There is no generic, uni®ed model that allows both design and analysis information to be speci®ed. In this paper, a feature-based CAD-CAE integration model is proposed to tackle the problem. The model comprises a hierarchy of CAD-CAE features such as part, wall, hole, rib, boss and treatment. The features are defined by their attributes and behaviours. With this model, information relating to both design
and analysis can be specified and modified. The specified information from the design process is used to activate relevant CAE analysis routines, thus supporting integration from the CAD to the CAE process. If any of the specified design constraints is not satisfied from the CAE results, the initial model can be modified and the CAE analysis executed again. Hence, the model also supports integration from the CAE to the CAD process. A design case illustrates the bidirectional integration process.
The task of design synthesis can be accomplished by human beings because of their ability to take into account the physics of the problem, past experience, and to evaluate a number of alternatives to determine the best compromise design. This paper illustrates a system that automates this procedure for injection mold design, and more specifically, gating design. The gating plan synthesis system described in this paper, automatically determines an initial gating configuration based on a features representation of the part and a knowledge-base that captures some of the design rules used in practice. A Feature Modeling Utility (FMU), a Topology and Geometry Utility System (TAGUS), and an automatic mesh generator, OCTREE, are used to identify and query features and to perform geometric reasoning about the part. The methodology used, implementation details, and examples of test cases are presented.
The placement of a gate in an injection mold is one of the most important variables of the total mold design. The quality of the molded part is greatly affected by the gate location, because it influences the manner in which the plastic flows into the mold cavity. Some defects, such as overpack and warpage, can be effectively controlled by the gate location. Therefore, product quality can be greatly improved by having an optimum gate location. In this investigation, a gate location optimization method was developed based on the minimization of the Standard Deviation of Flow Path Length (SDL) or Standard Deviation of Filling Time (SDT) during the mold filling process. The hill-climbing algorithm was implemented for flow path determination, which was subsequently utilized for gate location optimization. Both methods are applicable for parts of uniform thickness. However, SDT is superior for locating the optimum gate position than SDL for parts of non-uniform thickness. The applications of the methods are demonstrated on several numerical examples.
Manufacture of polymer composites using the process of liquid composite molding involves injection of a reactive resin into a closed mold with preplaced fibrous reinforcements. There are many studies that address the computer simulations for mold filling. The simulation programs provide the simulated mold filling results for a known gate location. However, they do not discuss the method for determination of the gate locations, which is one of the important issues in the total mold design. In this paper, a gate location optimization method was developed based on minimization of the mold filling pressure, uneven filling pattern, and temperature difference during the mold filling process. A genetic algorithm was used to search the optimal gate location. This method, in general, has a better chance to locate the near global optimum than the gradient based search method, especially in the problems with multiple variables and a large search space.
The objective is to develop a methodology that automatically predicts the “optimal” gate location(s) of injection molds based on injection-molding simulation. User-defined design evaluating criteria for three important parameters–-warpage, weld and meld lines in a constrained area, and Izod impact strength at the specific regions of the injection-molded part–-are introduced to determine the optimal gate location. Among the three parameters, the Izod impact strength is obtained using a previously trained neural network. The difficulty in predicting accurate values of engineering property like Izod impact strength is that they vary throughout a part with respect to the thermomechanical history. Upon evaluating each gate location, the trained neural network computation predicts, regardless of part geometry, Izod impact strength by a nonparameteric modeling of the complex relation with thermomechanical processing histories. The methodology comprises a two-stage process: (1) choosing the best among a set of gate locations generated based on a human designer's intuition, and (2) locally searching for the better gate location.
A prototype software system that automatically designs the gating and runner systems, which comprise the feed system, of injection molds is described. The system, called AMDS (Automated Mold Design System), integrates CAE, with iterative redesign and knowledge stored in a features representation of the part. Gating design involves the generation of the best gating configuration represented by number, location, and type of gates, and the determination of the best conditions under which plastic should enter through the gates. Runner design also involves the generation of a runner layout followed by the sizing of the runner segments. The design of both systems is iterative, whereby the design variables are changed, the new design analyzed, evaluated, and redesigned if necessary, until an acceptable design is obtained. The evaluation of the gating design is based on eighteen performance parameters, while the evaluation of the runner system is based on four performance parameters. The system has been tested on three-dimensional parts made up of planar rectangular wall features with holes as add-on features.
This paper addresses the determination of wall thicknesses and gating schemes in the preliminary design of injection- molded plastic parts. Today, most of the existing design guidelines come in the form of experience-based qualitative rules. If the designers already have a detailed geometry of the part, the numerical process simulation program provides another form of design aid. There exists a huge gap between these two types of design aids; the experience-based guidelines are often too vague, while the process simulation programs come too late to impact preliminary part design. To fill this gap, this paper develops physics-based guidelines that utilize dimensional analysis techniques. Experiments and simulation studies can deduce non-dimensional relationships between flow length, thickness, material, and process parameters. The guidelines will aid plastic component designers in determining wall-thickness, gating schemes, and in selecting the material in the preliminary stages of part design. This paper describes the formulation of the non-dimensional charts for fillability assessment, and explains the use of these charts in part design. We further outline an ongoing experimental program t o validate and refine our formulation.
The placement of a gate in an injection mold is one of the most important variables of the total mold design. The quality of the molded part is greatly affected by the gate location, because it influences the manner in which the plastic flows into the mold cavity. Some defects, such as weldline and overpack, can be effectively controlled only by the gate location. Therefore, the product quality can be greatly improved by determining the optimum gate location. In this paper, we develop a general methodology for gate location optimization. We first quantify quality in terms of flow simulation outputs. We can thus assess detrimental effects such as warpage and dimensional instability as a function of the independent variable, which is in this case the gate location. Next we develop methods to search for the optimum gate location. The search method introduced in this paper is a method that combines a deterministic hill climbing search with a stochastic annealing search method. The method is appropriately called simulated annealing and hill climbing (SANHIL). The criteria used for evaluation during the search process are a function of the flow simulation outputs. We demonstrate the success of the method for a complex industrial mold. The approach is applicable to any complex mold geometry and any plastic.
Cavity balancing is the process of altering the flow front within a cavity through thickness and design changes such that a desired fill pattern is achieved. This paper reports the preliminary research undertaken in developing an automated method for cavity balancing of two-dimensional cavities. The aim of the automated cavity balancing routine is to reduce product development time and to improve product quality. This will lower the level of prerequisite expert knowledge necessary for successful mold and part design. The automated cavity balancing routine has been developed using the concept of flow paths. The hill-climbing algorithm was employed on the cavity fill pattern for generation of the flow paths. Replacing the flow paths generated using the straight flow path assumption in previous work, this method was found to be more versatile and suitable to automation. No special considerations or routines were required to overcome the presence of inserts within the cavity. The method has been implemented in a computer program running as an external loop to the Moldflow software. The models analyzed demonstrate that the proposed method is viable and robust.
This paper describes a knowledge-based and object-oriented approach for the design of the feed system for plastic injection moulds. The gating system of a plastic injection mould plays a significant role in producing a quality part. Designing of this gating system entails a great amount of effort from an experienced designer and it is time-consuming. CADFEED (Computer-Aided Design of the FEED system of the plastic injection mould) is developed to accurately and efficiently design the type, location and size of a gating system of a plastic injection mould. This system provides an accurate and fast means of obtaining solutions based on the users' requirements, which are easily handled by the rating algorithm in the system. CADFEED generates acceptable solutions at a lower cost than most traditionally and commercially available analysis packages. This system can be used to verify designs proposed by the design engineers. It can also help novice engineers in the understanding of mould design. Another important feature of CADFEED is that it is a low cost system, which uses AutoCAD and an expert system shell on a personal computer. This feature makes CADFEED easily affordable by small-scale industries.
The integration of CAD, CAM and CAE is far from a commercial reality. Feature technology has been identified as a key element in bridging many of the integration gaps. This two-part paper emphasizes an integrated NMT-based environment that serves the needs of both geometry and feature-based applications. Part I describes a feature modeling utility that coexists with commercial CAD systems by providing external feature-based functionality and making it available to application programs. A non-manifold topologybased system, called TAGUS, is used to represent the model geometry and provide the foundation for features representation. The architecture of a feature-based analysis system is described and, finally, the automated design of the feed system for injection molds is presented as an example to illustrate the application of the feature modeling utility. A detailed description of this application is the focus of the companion paper (Part II).
The focus of this paper is on the application of the integrated non-manifold-topology-based CAE environment described in the companion paper (Part I). The need for both a geometry-based and a feature-based environment is illustrated through the application of the features modeling utility to automate the procedure for injection mold design and, more specifically, gating design. The gating plan synthesis system described in this paper automatically determines an initial gating configuration based on a features representation of the part and a knowledge-base that captures some of the design rules used in practice. The Features Modeling Utility (FMU), a Topology And Geometry Utility System (TAGUS) and an automatic mesh generator, OCTREE, are used to identify and query features and to perform geometric reasoning about the part. The methodology used, implementation details and examples of test cases are presented.
In the manufacturing industry, finding a suit-able location for the pin gate (the pin gate is the point from which liquid is poured or injected into a mold) is a difficult problem when viewed from the fluid dynamics of the molding process. However, experience has shown that a suitable pin gate location possesses several geometric characteristics. namely the distance from the pin gate to any point in the mold should be small and the number of turns on the path from a point in the mold to the pin gate should be small. We address the problem of computing locations that possess these geometric characteristics. Given a mold M (modeled by an n vertex simple polygon) we show how to compute the Euclidean center of M constrained to lie in the interior of A4 or on the boundary of A4 in O(n log n + k) time where k is the number of intersections between M and the furthest point Voronoi diagram of the vertices of M. We show how to compute the geodesic center of M constrained to the boundary in O(n log n) time and the geodesic center of M constrained to lie in a polygonal region in O(n(n + k)) time. Finally, we show how to compute the link center of A4 constrained to the boundary of M in O(n log n) time.Abstract: In the
Thesis (M.S.)--University of Maryland at College Park, 1989. Includes bibliographical references (leaves 84-87).
Thesis (Ph. D.)--Nanyang Technological University, School of Mechanical and Production Engineering, 2002.
In the manufacturing industry, finding a suitable location for the pin gate (the pin gate is the point from which liquid is poured or injected into a mold) is a difficult problem when viewed from the fluid dynamics of the molding process. However, experience has shown that a suitable pin gate location possesses several geometric characteristics, namely the distance from the pin gate to any point in the mold should be small and the number of turns on the path from a point in the mold to the pin gate should be small. We address the problem of computing locations that possess these geometric characteristics. Given a mold M (modeled by an n vertex simple polygon) we show how to compute the Euclidean center of M constrained to lie in the interior of M or on the boundary of M in O(n log n+k) time where k is the number of intersections between M and the furthest point Voronoi diagram of the vertices of M . We show how to compute the geodesic center of M constrained to the boundary in O(n log n) time and the geodesic center of M constrained to lie in a polygonal region in O(n(n + k)) time. Finally, we show how to compute the link center of M constrained to the boundary of M in O(n log n) time.
Design for Injection Molding: Using Dimensional Analysis to Assess Fillability
- D C Mehl
- K A Belter
- K Ishil
D. C. Mehl, K. A. Belter and K. Ishil, Design for Injection Molding: Using
Dimensional Analysis to Assess Fillability, Advances In Design Automation, 69(1), pp.
427-434, 1994.
Optimization of Gate Location for Plastic Injection Molding
- Y C Lam
- Lam
Optimization of Gate Location and Operational Molding Conditions for Injection Molding
- I Pandelidis
- Q Zou
- T J Lingard
I. Pandelidis, Q. Zou and T. J. Lingard, Optimization of Gate Location and
Operational Molding Conditions for Injection Molding, Proceedings of the Annual
Technical Conference of the Society of Plastics Engineers (ANTEC), Atlanta, Georgia,
April, pp 18-21, 1988.
Automatic Cavity Balancing in Plastic Injection Moulding
- L W Seow
L. W. Seow, Automatic Cavity Balancing in Plastic Injection Moulding, Master
thesis, Department of Mechanical Engineering, Monash University, Clayton, Victoria,
Australia, 1997.