scholarly journals Tie-Bar Elongation Based Filling-To-Packing Switchover Control and Prediction of Injection Molding Quality

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1168 ◽  
Author(s):  
Jian-Yu Chen ◽  
Chun-Ying Liu ◽  
Ming-Shyan Huang
Keyword(s):  
Injection Molding ◽  
Pressure Sensors ◽  
Clamping Force ◽  
Cavity Pressure ◽  
Testing Specimen ◽  
Injection Speed ◽  
Novel Approach ◽  
Pressure Profiles ◽  
Molded Parts ◽  
Short Shot

Filling-to-packing switchover (also called V/P switchover) is critical for assuring injection molding quality. An improper V/P switchover setting may result in various defects of injection-molded parts, such as excessive residual stress, flash, short shot, and warpage, etc. To enhance a consistent molding quality, recent V/P switchover approaches adopt cavity pressure profiles requiring sensors embedded in mold cavities, which is invasive to mold cavities and more expensive. Instead of using cavity pressure sensors, by working with the most popular screw position switchover control, this study hereby proposes a novel approach of tuning V/P switchover timing using a tie-bar elongation profile. In this investigation, a dumbbell testing specimen mold is applied to verify the feasibility of the method proposed. The results show that the mold filling and packing stages can be observed along the tie-bar elongation profile, detected by mounting strain gauges on the tie bars. Also, the characteristics of the cavity pressure are similar to those of the tie-bar elongation profile under a proper clamping force condition. Moreover, the varying process parameter settings which include injection speed, V/P switchover point, and holding pressure, can be reflected in these profiles. By extracting their characteristics, the application of the V/P switchover is proved to be realistic. This research conducted an experiment to verify the proposed V/P switchover decision method based on the tie-bar elongation profile. The result showed that the fluctuation of the part’s weight corresponding to a slight change of the barrel’s temperature from 210 °C to 215 °C can be successfully controlled with this method. Besides, the maximum clamping force increment extracted from the tie-bar elongation profile was found to be a good indicator for online monitoring of the reground material variation.

Influence of Injection Molding Parameters on the Consistency of Molding Process

2013 ◽  
Vol 446-447 ◽  
pp. 398-402
Author(s):  
S. Azmoudeh ◽  
H. Zamani ◽  
K. Shelesh-Nezhad
Keyword(s):  
Injection Molding ◽  
Signal To Noise Ratio ◽  
Injection Molding Process ◽  
Process Conditions ◽  
Cavity Pressure ◽  
Molding Process ◽  
Injection Speed ◽  
Taguchi Design Of Experiments ◽  
Pressure Profiles ◽  
Molded Parts

The existence of variations in the injection molding process conditions leads to the inconsistency of molded parts quality during the molding cycles. In this research, the variations of cavity pressure-time profiles integrals over the molding cycles were accounted as the molded parts quality variations. Thereafter, the correlations between injection molding process settings and the degree of consistency of molding process were investigated by applying cavity pressure measurement, Taguchi design of experiments approach and signal to noise ratio. The results derived from experiments indicated that an increase approximately as high as five times in the capability of injection molding may be achieved. Under the best setting condition, the cavity pressure profiles were relatively smooth and similar. Low screw rotational speed, high injection speed and short packing time led to the inconsistency elevation of injection molding.

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.

In-Mold Monitoring of Temperature and Cavity Pressure During the Injection Molding Process

2014 ◽  
Author(s):  
Catalin Fetecau ◽  
Felicia Stan ◽  
Laurentiu I. Sandu
Keyword(s):  
Injection Molding ◽  
Pressure Sensors ◽  
Temperature Sensors ◽  
Injection Molding Process ◽  
Cavity Pressure ◽  
Molding Process ◽  
Shear Rates ◽  
Wide Range ◽  
Simulation Results ◽  
Two Temperature

This paper focuses on the in-mold monitoring of temperature and cavity pressure. The melt contact temperature and the cavity pressure along the flow path were directly measured using two pressure sensors and two temperature sensors fitted into the cavity of a spiral mold. Three melt temperatures and dies of different heights (1.0, 1.5 and 2 mm) were used to achieve a wide range of practically relevant shear rates. In order to analyze the extent to which the numerical simulation can predict the behavior of the molten polymer during the injection molding process, molding experiments were simulated using the Moldflow software and the simulation results were compared with the experimental data under the same injection molding conditions.

Filling-to-Packing Switchover Mode Based on Cavity Pressure for Injection Molding

2012 ◽  
Vol 501 ◽  
pp. 168-173 ◽  
Author(s):  
Jian Wang
Keyword(s):  
Injection Molding ◽  
Crucial Role ◽  
Mold Temperature ◽  
The Other ◽  
Injection Time ◽  
Cavity Pressure ◽  
Part Quality ◽  
Molded Parts ◽  
Screw Position

Filling-to-packing switchover control during injection molding plays a crucial role in ensuring the quality of the molded parts. In this study, a filling-to-packing switchover mode based on cavity pressure was presented, and it was compared with other two switchover modes by injection time and screw position. The objective of this study was to validate the accuracy of the switchover mode based on cavity pressure, and examine its consistency. Weight of the molded parts served as the main measure to probe the process capabilities. In this study, the change in mold temperature was monitored; variation of mold temperature affecting the process was examined. The results of the verification experiments revealed that the switchover mode based on cavity pressure could yield a better part quality and consistent part weight compared with the other two traditional switchover modes. It was proved that the switchover mode by cavity pressure can be used to improve the precision of the injection molding. However, a suitable switchover pressure must be used for achieving such high process capability, and the position to get the pressure signal and mold temperature should also be considered.

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.

Warpage Characterization of Thin and Centrally-Gated Injection Molded Part by Applying Cavity Pressure Measurement

2013 ◽  
Vol 446-447 ◽  
pp. 1099-1103 ◽  
Author(s):  
H. Zamani ◽  
S. Azmoudeh ◽  
K. Shelesh-Nezhad
Keyword(s):  
Radial Flow ◽  
Mold Temperature ◽  
Cavity Pressure ◽  
Injection Speed ◽  
Molded Part ◽  
Pressure Time ◽  
Molded Parts ◽  
Injection Molded ◽  
Thin Disks

Two types of injection molded parts including parts with thin shell feature and parts molded with radial flow pattern are highly susceptible to the warpage. In this research, the warpage performance of a thin and centrally-gated disk was experimentally investigated. The melt pressure-time traces of two different locations inside the mold cavity were monitored by employing piezoelectric transducers. The results indicated that the pressure difference magnitude of melt at two locations along the radial flow path is related to the extent of molded part deformation. Moreover, it was pointed out that the high magnitude of warpage is because of two conflicting actions in the molded part comprising expansion as a result of viscoelastic recovery in the central region, and thermal contraction in the edge region of the thin disk. The molding variables encompassing injection speed, holding pressure, back pressure, mold temperature and screw rotational speed affected the thin disks deformation in order of significance.

Study on the End-Point Control of Holding Phase during Injection Molding

2009 ◽  
Vol 87-88 ◽  
pp. 222-227 ◽  
Author(s):  
Jian Wang ◽  
Peng Cheng Xie ◽  
Yu Mei Ding ◽  
Wei Min Yang
Keyword(s):  
Injection Molding ◽  
Mold Temperature ◽  
Control Methods ◽  
Cavity Pressure ◽  
Precise Control ◽  
End Point ◽  
Control Change ◽  
Molded Parts ◽  
Point Control ◽  
Product Weight

While the transfer from filling to packing is particularly crucial during injection molding, the transfers from packing to holding and holding to screw recovery also significantly affect part quality. In this study, the control of the transfer from holding to screw recovery, that is the control of the end-point of the holding phase, was examined. The holding end-point control by time, cavity pressure and cavity temperature were presented. The purpose of this study was to validate the feasibility of the control methods of holding end-point by cavity pressure and cavity temperature. The qualities of injection-molded parts, weight, will serve as measures to probe their process capabilities. Recently found to be a good indicator of product quality, both cavity pressure and temperature profiles are applied here to obtain more precise control. Change of mold temperature was specially considered. After the experimental verification is conducted, the results reveal that the innovative holding end-point control by cavity temperature yields a more uniform product weight with mold temperature. It proved that the holding end-point control by cavity temperature can be used to obtain the optimum holding time and accommodate the product weight to the change of mold temperature, which is the other holding control methods cannot obtain.

End-Point Control of Holding Phase Based on Cavity Pressure for Injection Molding

2011 ◽  
Vol 221 ◽  
pp. 333-337
Author(s):  
Jian Wang ◽  
Peng Cheng Xie ◽  
Wei Min Yang
Keyword(s):  
Injection Molding ◽  
Control Method ◽  
Holding Time ◽  
Control Mode ◽  
Cavity Pressure ◽  
End Point ◽  
Sensor Position ◽  
Molded Parts ◽  
Point Control

While the switchover from filling to packing is particularly crucial during injection molding, the transfers from holding to screw recovery also significantly affects the quality of molded parts. In this study, the end-point control of the holding phase based on cavity pressure was presented. It was compared with the traditional control method by holding time. The purpose of this study was to validate the feasibility of the end-point control of holding phase by cavity pressure, and to examine its consistency. The weight of the molded parts served as the main measure to probe the process’s capabilities. The results of the verification experiments revealed that the end-point control mode based on cavity pressure could yield better consistency of part weight than the traditional control method by holding time, however, the benefits were not significant. The trigger value of cavity pressure and sensor position should be considered for achieving such high process capabilities.

scholarly journals A Novel Multiscale Methodology for Simulating Droplet Morphology Evolution during Injection Molding of Polymer Blends

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 133
Author(s):  
Lin Deng ◽  
Suo Fan ◽  
Yun Zhang ◽  
Zhigao Huang ◽  
Shaofei Jiang ◽  
...  
Keyword(s):  
Injection Molding ◽  
Polymer Blends ◽  
Critical Role ◽  
Pressure Sensors ◽  
Underlying Mechanism ◽  
Mold Filling ◽  
Morphology Evolution ◽  
Filling Process ◽  
Molded Parts ◽  
Droplet Morphology

The morphology of polymer blends plays a critical role in determining the properties of the blends and performance of resulting injection-molded parts. However, it is currently impossible to predict the morphology evolution during injection molding and the final micro-structure of the molded parts, as the existing models for the morphology evolution of polymer blends are still limited to a few simple flow fields. To fill this gap, this paper proposed a novel model for droplet morphology evolution during the mold filling process of polymer blends by coupling the models on macro- and meso-scales. The proposed model was verified by the injection molding experiment of PP/POE blends. The predicted curve of mold cavity pressure during filling process agreed precisely with the data of the corresponding pressure sensors. On the other hand, the model successfully tracked the moving trajectory and simulated morphology evolution of the droplets during the mold-filling process. After mold-filling ended, the simulation results of the final morphology of the droplets were consistent with the observations of the scanning electron microscope (SEM) experiment. Moreover, this study revealed the underlying mechanism of the droplet morphology evolution through the force analysis on the droplet. It is validated that the present model is a qualified tool for simulating the morphology evolution of polymer blends during injection molding and predicting the final microstructure of the products.

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