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This paper presents the multi-objective optimization in injection molding. The aim of this study is to determine the best alternative for the best moldability index and better alternatives which are close to the best alternative for an injected part in injection molding technology. Consideration of Taguchi and fuzzy analytic hierarchy process (FAHP) with technique for the order performance by its similarity to the ideal solution (TOPSIS) offers an efficient use approach to evaluate different objectives. Three common defects which reduce the final quality of the injected parts are short shot possibility, shrinkage rate and warpage. The selected material for injection is polypropylene. L18 orthogonal array of Taguchi is selected and for gaining accurate results, Finite Element Analysis (FEA) is applied. To validate the simulation result, the experiment is carried out for two circular flat plates with thickness of 1. mm. Finally, the highest moldability index is related to trial 2 for both simulation and experimental results. This study outcome shows instead of having one trial number which has the highest moldability index, there are 10 trial numbers with high moldability index between 0.6-1 for simulation results and 5 trial numbers with high moldability index between 0.6-1 for experimental results. It is clear, by using Taguchi with TOPSIS and FAHP if the best alternative is not possible to maintain, there are other alternatives which are very close to the best alternative with high moldability index. The main advantage of the proposed method is to increase the number of alternatives which in turn increases the moldability of the final product in injection molding. Refereed/Peer-reviewed

This paper presents the analysis of short shot possibility in injection molding. The aim of this research is to evaluate process and geometric parameters which increase the possibility of short shot in an injected part based on the proposed method. The analysis of short shot possibility was conducted via SolidWorks Plastics and Taguchi method for orthogonal array experiment of L18 to find the significant process and geometric parameters. Finite element method (FEM) is employed in SolidWorks Plastics for simulation. To validate the simulation result, an experimental study was conducted for two circular flat polypropylene of 1-mm thickness. Filling time, part cooling time, pressure holding time, and melt temperature were selected as process parameters, and gate type was selected as a geometric parameter. A new method of analysis for short shot defect is proposed herein to predict the possibility of short shot in injection molding before it occurs. The significance rate of each parameter in both experiments and simulation result was very close together which signifies the robustness of proposed method in evaluation of short shot possibility. Melt temperature was the most influential parameter with a contribution of 74.25 and 75.04%, and filling time with a contribution of 22 and 20.19% followed by gate type with a contribution of 3.69 and 3.93% for simulation and experimental results, respectively. Hence, based on response table of S/N ratio, the optimum levels of each parameter which leads to reduction in possibility of short shot are gate type at level 1, filling time at level 3, and melt temperature at level 3. Finally, melt temperature, filling time, and gate type considered as significant parameters which affect the possibility of short shot in injected parts. Refereed/Peer-reviewed

The reliability of the measurement system, accuracy, and precision are significant criteria at any measurement procedure. Strain gage sensors are one of the tools to measure the strain of structures in engineering applications. Different controllable and extraneous parameters will change the accuracy and precision of the strain gauges. As a result, it is valuable to investigate the most significant parameters and the percentage of their contributions affecting the strain measurement. This paper presents the multi-objective optimization in strain gauge measurements to determine the Reliability and Noise indices. The best set of parameters with a high-reliability index (which means low noise index) for strain measurement based on two significant objectives of accuracy and precision are evaluated. The significant parameters, their optimal levels and percentage of contributions are identified according to the Taguchi and Fuzzy Analytic Hierarchy Process (FAHP) with Technique for the Order Performance by its Similarity to the Ideal Solution (TOPSIS) methods. To obtain this evaluation, three levels (L1, L2, and L3) of temperature (P1), the length of wires (P2), and the point of applied force (P3) are considered. This configuration leads to L9 orthogonal array of Taguchi approach based on the number of parameters and their levels. The triangular membership function for the weightiness of accuracy and precision is used via AHP. By using the Taguchi method, the optimum set of parameters are identified as P1 at L1, P2 at L2, and P3 at L3 to have a higher reliability index compared to trial 8. By applying the optimum design of experiment, it is found that the reliability index is 95%. The results also show that the highest reliability index is related to trial 8 with 87.65% reliability. Finally, the combination of FAHP and TOPSIS with Taguchi method for multi-objective optimization is introduced and proposed as a practical and useful model to determine the best set of parameters with the highest reliability index in strain measurement. Refereed/Peer-reviewed

This paper presents a new cross sectional shape of runner system in the injection molding. The aim of the new geometry is to reduce the scrap and cycle time and also the easier ejection of runner system from mold tools. Short shot defect in the plastic part during the injection molding process is analyzed by Solid Works Plastic to validate the new proposed geometry. Runner system with elliptical cross section is proposed with different ratio for two circular flat plates with thickness of 1mm. Finite Element Method (FEM) is employed in Solid Works Plastic for simulation of injected part. Filling time, melt temperature, mold temperature, pressure holding time, and pure cooling time are chosen as input for the injection machine. The contribution of this study is the design of new geometry of cold runner system for reduction in scrap and cycle time and also easier ejection of runner system in injection molding. This study outcomes show no short shot defect with the new geometry. Also, it was shown the significant reduction in scarp and cooling time. 25% and 2.5% reduction in scrap and cooling time were achieved compared to round cross section, respectively. Reduction in contact surface of runner system with mold walls improved the easier ejection of runner system out of the cavity as well. Refereed/Peer-reviewed

Thesis (PhD(Mechanical and Manufacturing Engineering))--University of South Australia, 2017. Includes bibliographical references (pages [144]-152) The limitations associated with these studies are: (1) improving the quality of injected parts was mostly based on the process parameters (i.e. without consideration of geometric parameters); (2) only a limited number of optimization and statistical methods were combined together for the evaluation of process parameters. Based on these limitations, this research presents a new approach for improving the quality of injected parts, reducing scrap and also the optimization of injection molding process via four developments, namely a new cross section for runners which leads to 20%reduction in scrap rate and 2.5% reduction in cooling time, and easier ejection of runner from the cavity; a new cross section for gates which leads to less internal and external defects with 40% reduction in scrap rate ; determination of short shot defects before it happens and finding the significant parameters which affect the short shot possibility; and determination of moldability index in injection molding process which show a number of alternatives with high moldability index.

This paper presents a new cross sectional shape of the runner system in the mold design of the injection molding process. The aim of the new geometry is to reduce scrap, cycle time and ease the ejection of runner system from mold tools. An elliptical cross sectional shape of runner with different ratios was proposed for two circular flat plates with thickness 1 mm. Finite element method (FEM) is employed in Solid Works Plastic for simulation of the injected part. Short shot defect in the plastic part during the injection molding process is analyzed by Solid Works Plastic to validate the new proposed geometry. An experimental study of the injection molding process of polypropylene circular flat plates is conducted for the new geometry. The input machine parameters selected are filling time, melt temperature,mold temperature, pressure holding time, and pure cooling time. The research outcomes show no short shot defect associated with the new geometry and also significant 25 and 2.5 % reduction in scrap and cooling time respectively compared to round cross sections. Reduction in contact surface of the runner system with mold walls improved the ease of ejection of runner system out of the cavity as well. The contribution of this study is to design a new geometry of a cold runner system to reduce scrap, cycle time and also provide easy ejection of runner system in the injection molding. Refereed/Peer-reviewed

This paper presents a new geometry of an edge gate in the injection molding process called modified edge gate. The corners of current edge gate result in the turbulence of molten plastic into the cavity which leads to internal and external defects. The aim of the new geometry is to reduce the internal and external defects of injected part such as sink marks and short shot. The easier de-gating analysis for the new geometry to decrease the visible blemish of the injected part was proposed in this study. A modified edge gate was proposed for two circular flat plates with thickness 1 mm. Finite element method (FEM) was used along with SolidWorks plastic. Internal and external defects of the injected part were analyzed via SolidWorks plastic. To validate the new geometry, an experimental study was implemented for two polypropylene (PP) circular flat plates with modified edge gate to confirm the simulation results. The contribution of this research is to modify the geometry of current edge gate by removing the corners of rectangular edge gate which leads to the reduction of scrap. The new geometry presents easier degating of gate and less visible blemish of the injected part. A smooth flow of molten plastic into the cavities reduces the internal and external defects. The outcome of this study demonstrates filling of the cavities with no short shot. In addition, no sink marks were detected with modified edge gate. Finally, the modified edge gate has less visible blemish on the injected part in comparison with current edge gate. Refereed/Peer-reviewed

This paper presents an evaluation of a plastic defect in injection molding before it occurs in the process; it is known as the short shot defect. The evaluation of different parameters which affect the possibility of short shot defect is the aim of this paper. The analysis of short shot possibility is conducted via SolidWorks Plastics and Taguchi method to determine the most significant parameters. Finite Element Method (FEM) is employed to analyze two circular flat polypropylene plates of 1 mm thickness. Filling time, part cooling time, pressure holding time, melt temperature and gate type are chosen as process and geometric parameters, respectively. A methodology is presented herein to predict the possibility of the short-shot occurrence. The analysis determined melt temperature is the most influential parameter affecting the possibility of short shot defect with a contribution of 74.25%, and filling time with a contribution of 22%, followed by gate type with a contribution of 3.69%. It was also determined the optimum level of each parameter leading to a reduction in the possibility of short shot are gate type at level 1, filling time at level 3 and melt temperature at level 3. Finally, the most significant parameters affecting the possibility of short shot were determined to be melt temperature, filling time, and gate type.

Moulded parts contribute to more than 70% of components in products. However, common defects particularly in plastic injection moulding exist such as: warpage, shrinkage, sink marks, and weld lines. In this paper Taguchi experimental design methods are applied to reduce the warpage defect of thin plate Acrylonitrile Butadiene Styrene (ABS) and are demonstrated in two levels; namely, orthogonal arrays of Taguchi and the Analysis of Variance (ANOVA). Eight trials have been run in which the optimal parameters that can minimize the warpage defect in factorial experiment are obtained. The results obtained from ANOVA approach analysis with respect to those derived from MINITAB illustrate the most significant factors which may cause warpage in injection moulding process. Moreover, ANOVA approach in comparison with other approaches like S/N ratio is more accurate and with the interaction of factors it is possible to achieve higher and the better outcomes. Refereed/Peer-reviewed

Mould making is one important industry involved in our life, since moulded products contribute to more than %70 of components in products. However, there exist common defects in any moulding process particularly in plastic injection moulding such as: warpage, shrinkage, sink marks, and weld lines. Also, appropriate parameters settings were determined using Taguchi's experimental design method. Based on data measurement sensitivity, through trial and error method the optimum alpha rate; 0.8 was chosen. Furthermore, p rate for each parameter (A, S, and C) and their combinations (AB, AC, and Be) were identified. As a result A, B, AB, and AC were significant factors, while C and AC were insignificant. The results obtained from ANOV A approach analysis with respect to those derived from MINIT AB illustrate, in former, A and B are the most significant factors which may cause warpage in injection moulding process. Moreover, ANOV A approach in comparison with other approaches like SIN ratio is much more accurate, resulting from the alpha rate, and also the interaction of factors is possible to achieve the higher and the better outcomes. In this paper, two distinctive approaches of Taguchi method, to reduce the warpage defect of thin plate Acrylonitrile Butadiene Styrene (ABS), will be implemented in two levels; namely, orthogonal arrays of Taguchi and the Analysis of Variance (ANOVA). In order to improve this process, injection pressure (A), packing time (B) and cooling time(C) were identified as the most effective factors. Refereed/Peer-reviewed