scholarly journals Welding lines formation in holes obtained by low pressure injection molding of ceramic parts

Cerâmica ◽  
2018 ◽  
Vol 64 (369) ◽  
pp. 97-103 ◽  
Author(s):  
C. A. Costa ◽  
A. F. Michels ◽  
M. E. Kipper
Keyword(s):  
Injection Molding ◽  
Injection Pressure ◽  
Mold Temperature ◽  
Low Pressure ◽  
Process Conditions ◽  
Injection Mold ◽  
Extraction Temperature ◽  
Post Injection ◽  
Injection Process ◽  
Pressure Injection

Abstract This work presents a study to evaluate the process of producing internal holes in ceramic disks produced by low pressure injection molding (LPIM) process. Two process conditions defined as pre-injection and post-injection were used to test the proposition. In the first one the pin cores that produce the holes were positioned in the cavity before the injection of the feedstock; and in the second one, the pin cores were positioned in the cavity, just after the feeding phase of the injection mold. An experimental injection mold designed and manufactured to test both processes was developed to produce ceramic disk with Ø 50 x 2 mm with four holes of Ø 5 mm, equally and radially distributed through the disk. The feedstock was composed of 86 wt% alumina (Al2O3) and 14 wt% organic vehicle based on paraffin wax. Heating and cooling systems controlled by a data acquisition system were included in the mold. The results showed that there were no welding lines with the post-injection process, proving to be an option for creating holes in the ceramic parts produced by LPIM. It was observed that best results were obtained at 58 °C mold temperature. The pins extraction temperature was about 45 °C, and the injection pressure was 170 kPa.

Effect of Processing Conditions on the Shrinkage and Warpage of Glass Fiber Reinforced PP Using Microcellular Injection Molding

2012 ◽  
Vol 501 ◽  
pp. 294-299 ◽  
Author(s):  
Zhi Bian ◽  
Peng Cheng Xie ◽  
Yu Mei Ding ◽  
Wei Min Yang
Keyword(s):  
Injection Molding ◽  
Glass Fiber ◽  
Injection Pressure ◽  
Mold Temperature ◽  
Process Conditions ◽  
Fiber Reinforced ◽  
Injection Speed ◽  
Glass Fiber Reinforced ◽  
Microcellular Injection Molding ◽  
Molded Parts

This study was aimed at understanding how the process conditions affected the dimensional stability of glass fiber reinforced PP by microcellular injection molding. A design of experiments (DOE) was performed and plane test specimens were produced for the shrinkage and warpage analysis. Injection molding trials were performed by systematically adjusting six process parameters (i.e., Injection speed, Injection pressure, Shot temperature, SCF level, Mold temperature, and Cooling time). By analyzing the statistically significant main and two-factor interaction effects, the results showed that the supercritical fluid (SCF) level and the injection speed affected the shrinkage and warpage of microcellular injection molded parts the most.

Fabrication of Supports for Solid Oxide Fuel Cells by Powder Injection Molding

2011 ◽  
Author(s):  
Ali Keshavarz Panahi ◽  
Hadi Miyanaji ◽  
Moein Taheri ◽  
Milad Janbakhsh
Keyword(s):  
Injection Molding ◽  
Weld Line ◽  
Injection Pressure ◽  
Mold Temperature ◽  
Injection Rate ◽  
Powder Injection ◽  
Pressure Injection ◽  
Packing Pressure ◽  
Molded Parts ◽  
Short Shot

In this paper the processing steps for producing SOFC (Solid Oxide Fuel Cell) supports by means of PIM (Powder Injection Molding) technique were investigated. Injection molding parameters in this study were divided into pressure-related (injection pressure and packing pressure), temperature-related (nozzle temperature and mold temperature), and time-related (injection rate and holding time) parameters. Keeping the other parameters (pressure-related, temperature-related and time-related parameters) constant at an optimized value, the effects of each of the molding parameters above were investigated. The results show that the short shot, warpage, weld line and void are the most common defects in molded parts. According to the results the short shot could be seen in low values of injection pressure, injection rate, nozzle and mold temperature. Also, warpage could be seen in high values of mold temperature, injection and packing pressure. Poor weld line was another defect that could be seen in low values of injection pressure, injection rate, nozzle and mold temperature. Also the void was one of the most common defects that could be seen in high values of injection rate and nozzle temperatures. Finally, using optimized molding parameters, the molded parts underwent debinding and sintering processes. Based on the results of thermal shock tests and the porosity measurements of the sintered parts, these molded parts possessed relatively desirable characteristics.

Multiple Performance Optimization for the Best Injection Molding Process of Ti-6Al-4V Green Compact

2010 ◽  
Vol 44-47 ◽  
pp. 2707-2711 ◽  
Author(s):  
Norhamidi Muhamad ◽  
Nor Hafiez Mohamad Nor ◽  
Sufizar Ahmad ◽  
Mohd Halim Irwan Ibrahim ◽  
Mohd Ruzi Harun
Keyword(s):  
Injection Molding ◽  
Confidence Level ◽  
Performance Optimization ◽  
Injection Pressure ◽  
Mold Temperature ◽  
Powder Injection ◽  
Injection Molding Process ◽  
Pressure Injection ◽  
Injection Temperature ◽  
Grey Relational

The L27 (313) Taguchi orthogonal array is used in the experiment while the injection pressure, injection temperature, powder loading, mold temperature, holding pressure and injection speed are optimized in this study. A grey relational grade (GRG) obtained from the grey relational analysis (GRA) is used to solve the titanium alloy powder injection molding operations with the multiple performance characteristics such as strength and density. From the analysis of variance (ANOVA), the injection temperature has the highest contribution at confidence level 90% to the quality of green part followed by powder loading. The others factor such as mold temperature, holding pressure, injection pressure and injection rate and all the interactions are not significant even though it give contribution during injection molding but the confidence level are less than 90%.

Optimization of Process Parameters for Injection Molding Based on Taguchi Technique

2012 ◽  
Vol 538-541 ◽  
pp. 1170-1174
Author(s):  
Shi Jun Fu
Keyword(s):  
Injection Molding ◽  
Process Parameters ◽  
Orthogonal Design ◽  
Mold Temperature ◽  
Optimum Process ◽  
Process Conditions ◽  
Injection Time ◽  
Melt Temperature ◽  
Injection Process ◽  
Packing Pressure

In this paper, Taguchi and CAE technique are combined to study the influence of process conditions on the warpage of injection molding parts through twice orthogonal design experiments, and the injection process parameters are optimized according to the warpage. For the parameters selected, melt temperature and packing pressure have effects on the warpage of injection molding parts are highly significant, injection time is significant, other parameters have little effects. Within the range of experiments, the warpage decreased with the rise of the melt temperature and packing pressure. At last, the optimum process parameters of injection are that the mold temperature is 60°C, packing time is 10s, melt temperature is240°C, packing pressure is 115MPa and injection time is 0.4s.

Low-pressure injection molding processing of a 316-L stainless steel feedstock

2002 ◽  
Vol 52 (4-5) ◽  
pp. 360-365 ◽  
Author(s):  
M Rei ◽  
E.C Milke ◽  
R.M Gomes ◽  
L Schaeffer ◽  
J.P Souza
Keyword(s):  
Stainless Steel ◽  
Injection Molding ◽  
Low Pressure ◽  
Pressure Injection ◽  
316 L Stainless Steel

scholarly journals Post-Processing Time Dependence of Shrinkage and Mechanical Properties of Injection-Molded Polypropylene

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 22
Author(s):  
Artur Kościuszko ◽  
Dawid Marciniak ◽  
Dariusz Sykutera
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Injection Molding ◽  
Accelerated Aging ◽  
Mold Temperature ◽  
Degree Of Crystallinity ◽  
Injection Mold ◽  
Secondary Crystallization ◽  
Scanning Calorimetry ◽  
Injection Molded

Dimensions of the injection-molded semi-crystalline materials (polymeric products) decrease with the time that elapses from their formation. The post-molding shrinkage is an effect of secondary crystallization; the increase in the degree of polymer crystallinity leads to an increase in stiffness and decrease in impact strength of the polymer material. The aim of this study was to assess the changes in the values of post-molding shrinkage of polypropylene produced by injection molding at two different temperatures of the mold (20 °C and 80 °C), and conditioned for 504 h at 23 °C. Subsequently, the samples were annealed for 24 h at 140 °C in order to conduct their accelerated aging. The results of shrinkage tests were related to the changes of mechanical properties that accompany the secondary crystallization. The degree of crystallinity of the conditioned samples was determined by means of density measurements and differential scanning calorimetry. It was found that the changes in the length of the moldings that took place after removal from the injection mold were accompanied by an increase of 20% in the modulus of elasticity, regardless of the conditions under which the samples were made. The differences in the shrinkage and mechanical properties of the samples resulting from mold temperature, as determined by tensile test, were removed by annealing. However, the samples made at two different injection mold temperature values still significantly differed in impact strength, the values of which were clearly higher for the annealed samples compared to the results determined for the samples immediately after the injection molding.

scholarly journals Optimization of Process Parameters for Vertical-Faced Polypropylene Bottle Injection Molding

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Youmin Wang ◽  
Zhichao Yan ◽  
Xuejun Shan
Keyword(s):  
Injection Molding ◽  
Process Parameters ◽  
Dwell Time ◽  
Optimization Problem ◽  
Injection Pressure ◽  
Mold Temperature ◽  
Orthogonal Test ◽  
Injection Molding Process ◽  
Injection Time ◽  
Melt Temperature

In order to obtain the optimal combination of process parameters for vertical-faced polypropylene bottle injection molding, with UG, the model of the bottle was drawn, and then, one module and sixteen-cavity injection molding system was established and analyzed using Moldflow. For filling and maintaining pressure during the process of infusion bottle injection molding, the orthogonal test table L25 (56) using CAE was designed for injection molding of the bottle, with six parameters such as melt temperature, mold temperature, injection pressure, injection time, dwell pressure, and dwell time as orthogonal test factors. By finding the best combination of process parameters, the orthogonal experiment was completed, the results were analyzed by range analysis, and the order of influence of each process parameter on each direction of optimization was obtained. The prediction dates of the infusion bottle were gained under various parameters, a comprehensive quality evaluation index of the bottle was formulated, and the multiobjective optimization problem of injection molding process was transformed into a single-objective optimization problem by the integrated weighted score method. The bottle parameters were optimized by analyzing the range date of the weighted scoring method, and the best parameter combination such as melt temperature 200°C, mold temperature 80°C, injection pressure 40 MPa, injection time 2.1 S, dwell pressure 40 MPa, and dwell time 40 S was gained.

A New Dewaxing Method and its Effect on the Properties of Low-Pressure Injection Molded Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 1012-1016
Author(s):  
Yin Wu ◽  
Wen Jie Si ◽  
He Zhuo Miao
Keyword(s):  
Carbon Dioxide ◽  
Injection Molding ◽  
Bending Strength ◽  
Low Pressure ◽  
Supercritical Extraction ◽  
Paraffin Wax ◽  
Organic Additives ◽  
Extraction Condition ◽  
Pressure Injection ◽  
Injection Molded

A new dewaxing method for low-pressure injection molded ceramics is presented. Supercritical extraction with carbon dioxide was used to remove paraffin wax from the ceramic green parts. The composition of organic additives for low-pressure injection molding feedstock and the extraction condition for the green parts were investigated. Moreover, the properties of sintered ceramic samples dewaxed by supercritical carbon dioxide were compared with those by thermal dewaxing. The results show that the new binder system containing 50wt% paraffin wax, 35% bee wax and 15% stearic acid fulfills the requirements of both low-pressure injection molding feedstocks and supercritical dewaxing, where the feedstock has high fluidity, low viscosity and quick solidification. The efficient extraction condition for supercritical dewaxing from the green parts is at 30MPa pressure and 45°C. Under this condition, defect free ceramic green parts can be obtained. Dewaxing methods have significant influence on the properties of sintered parts. The mechanical properties of the sintered sample can be improved by supercritical dewaxing. With this method, the bending strength of sintered samples (σ = 331.6 MPa) is higher than that obtained by thermal treatment (σ = 312.3MPa). The sintered samples dewaxed by supercritical CO2 have shown the property of higher density and less distortion compared to the thermal dewaxing method. Moreover, with supercritical extraction the dewaxing time can be reduced to about one tenth of the time required by thermal dewaxing.

Coated Composite Crosstie Mold Structure Design Used for Experiment with Inventor, Moldflow and Ansys

2013 ◽  
Vol 561 ◽  
pp. 196-200
Author(s):  
Yu Guang Gong ◽  
Zhi Wen Zong ◽  
Ying Yu ◽  
Bai Yuan Lv
Keyword(s):  
Simulation Analysis ◽  
Displacement Vector ◽  
Processing Parameters ◽  
Structure Design ◽  
Mold Cavity ◽  
Von Mises Stress ◽  
Process Conditions ◽  
Injection Mold ◽  
Injection Process ◽  
Von Mises

Coated crosstie products and counter mold components are created in 3-D model using Inventor software, preparing for CAE analysis. By using Moldflow software , to determine products gate location, filling, packing, cooling, push-out processing, as well as the injection process conditions optimization of simulation analysis to find possible defects, modify and optimize the design, determine the best processing parameters and conditions. Binding using Ansys11.0 software to analyze rail sleeper mold cavity deformation, structure stress, get distribution of property of von Mises stress and displacement vector sum, in the mold cavity on the contact surface. By changing the cavity wall thickness, and other factors to improve the force which it is subjected, providing references to structure optimization of injection mold design. It has been proven that in collaborative application of these three softwares, the design of the injection mold is a very efficient and easy.

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