scholarly journals Micro-Ultrasonic Viscosity Model Based on Ultrasonic-Assisted Vibration Micro-Injection for High-Flow Length Ratio Parts

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 522 ◽  
Author(s):  
Yan Lou ◽  
Jianjun Xiong
Keyword(s):  
Injection Molding ◽  
Ultrasound Velocity ◽  
High Flow ◽  
Ultrasonic Energy ◽  
Viscosity Model ◽  
Length Ratio ◽  
Model Based ◽  
Flow Length ◽  
Ultrasonic Assisted ◽  
Filling Capacity

A micro-ultrasonic (MU) viscosity model based on ultrasonic-assisted vibration micro-injection for high- flow length ratio polymer parts was established. This model considered the effects of ultrasonic energy and the characteristic microdimension. Ultrasonic energy parameters (such as the ultrasonic amplitude, frequency, and ultrasound velocity), the characteristic microdimension, and the molecular chain length (MCL) were introduced into the MU viscosity model. An ultrasonic micro-injection experimental platform was built on an injection molding machine. Polypropylene (PP) filling experiments were carried out using microgrooves with different flow length ratios (depth-to-width ratios of 3:1, 5:1, and 10:1). The validity and accuracy of the MU viscosity model were examined through a filling experiment with polypropylene (PP) microgroove injection molding and by a flow pressure difference experiment with polystyrene (PS). The results showed that the MU viscosity model was in better agreement with the experimental results compared to other models. The maximum error of the MU model was 4.9%. Ultrasound-assisted vibration had great effects on the filling capacity for microgrooves with high flow length ratios (depth-to-width ratios greater than 5:1). The filling capacity increased as the ultrasonic amplitude increased.

scholarly journals Study on External Gas-Assisted Mold Temperature Control with the Assistance of a Flow Focusing Device in the Injection Molding Process

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 965 ◽  
Author(s):  
Nguyen Truong Giang ◽  
Pham Son Minh ◽  
Tran Anh Son ◽  
Tran Minh The Uyen ◽  
Thanh-Hai Nguyen ◽  
...  
Keyword(s):  
Injection Molding ◽  
Temperature Control ◽  
Mold Temperature ◽  
Injection Molding Process ◽  
Melt Flow ◽  
Flow Focusing ◽  
Molding Process ◽  
Heating Efficiency ◽  
Flow Length ◽  
Insert Plate

In the injection molding field, the flow of plastic material is one of the most important issues, especially regarding the ability of melted plastic to fill the thin walls of products. To improve the melt flow length, a high mold temperature was applied with pre-heating of the cavity surface. In this paper, we present our research on the injection molding process with pre-heating by external gas-assisted mold temperature control. After this, we observed an improvement in the melt flow length into thin-walled products due to the high mold temperature during the filling step. In addition, to develop the heating efficiency, a flow focusing device (FFD) was applied and verified. The simulations and experiments were carried out within an air temperature of 400 °C and heating time of 20 s to investigate a flow focusing device to assist with external gas-assisted mold temperature control (Ex-GMTC), with the application of various FFD types for the temperature distribution of the insert plate. The heating process was applied for a simple insert model with dimensions of 50 mm × 50 mm × 2 mm, in order to verify the influence of the FFD geometry on the heating result. After that, Ex-GMTC with the assistance of FFD was carried out for a mold-reading process, and the FFD influence was estimated by the mold heating result and the improvement of the melt flow length using acrylonitrile butadiene styrene (ABS). The results show that the air sprue gap (h) significantly affects the temperature of the insert and an air sprue gap of 3 mm gives the best heating rate, with the highest temperature being 321.2 °C. Likewise, the actual results show that the height of the flow focusing device (V) also influences the temperature of the insert plate and that a 5 mm high FFD gives the best results with a maximum temperature of 332.3 °C. Moreover, the heating efficiency when using FFD is always higher than without FFD. After examining the effect of FFD, its application was considered, in order to improve the melt flow length in injection molding, which increased from 38.6 to 170 mm, while the balance of the melt filling was also clearly improved.

Estimation of Maximum Flow Length for CF-PEEK Overmolded Grid Structures Using the Finite Element Method

2021 ◽  
Author(s):  
Carlos Rodríguez-Mondéjar ◽  
Álvaro Rodríguez-Prieto ◽  
Ana María Camacho
Keyword(s):  
Aspect Ratio ◽  
Injection Molding ◽  
Cross Section ◽  
Maximum Flow ◽  
Thermoplastic Composites ◽  
Injection Molding Process ◽  
Geometrical Parameters ◽  
Molding Process ◽  
Support Tool ◽  
Flow Length

Abstract Injection overmolding process is a high versatile process that permits, when used in combination with fiber reinforced thermoplastic composites, the obtaining of high mechanical properties structures with complex geometries in short time cycles. The maximum flow length is a parameter that reflects the success of filling in a polymer injection molding process. Geometry of the part, rheological properties of the polymer and process parameters, such as injection pressure and temperature, are involved on the value of this parameter and therefore on the viability of a certain configuration. For injection molding manufacturing, the understanding of the relation between maximum flow length and main geometrical parameters of the molded part is fundamental to approach the product design, which is conditioned severely by processing capabilities. In this work, the maximum flow length is obtained for different geometries of an overmolded rectangular stiffener grid of carbon fiber filled polyether eter ketone (CF-PEEK) using the software Moldflow© Adviser© for calculations. Value of maximum flow length is provided as a function of cross section aspect ratio for gate diameters between 0.8 mm and 1.4 mm and cross section areas from 10 to 50 mm2. An exponential decrement of maximum flow length has been observed with the increment of aspect ratio of the cross section as well as a linear increment with the increment of cross section area. Gate diameter variation is slightly related with maximum flow length for the simulated values. These results provide a support tool for geometry sizing in overmolded rectangular grid parts at preliminary design stages.

scholarly journals Prediction of the maximum flow length of a thin injection molded part

2020 ◽  
Vol 40 (9) ◽  
pp. 783-795
Author(s):  
Sara Liparoti ◽  
Vito Speranza ◽  
Annarita De Meo ◽  
Felice De Santis ◽  
Roberto Pantani
Keyword(s):  
Injection Molding ◽  
Maximum Flow ◽  
Mold Temperature ◽  
Complete Characterization ◽  
Rheological Parameters ◽  
Injection Molding Process ◽  
Spiral Flow ◽  
Molding Process ◽  
Molded Part ◽  
Flow Length

AbstractOne of the most significant issues, when thin parts have to be obtained by injection molding (i.e. in micro-injection molding), is the determination of the conditions of pressure, mold temperature, and injection temperature to adopt to completely fill the cavity. Obviously, modern computational methods allow the simulation of the injection molding process for any material and any cavity geometry. However, this simulation requires a complete characterization of the material for what concerns the rheological and thermal parameters, and also a suitable criterion for solidification. These parameters are not always easily reachable. A simple test aimed at obtaining the required parameters is then highly advantageous. The so-called spiral flow test, consisting of measuring the length reached by a polymer in a long cavity under different molding conditions, is a method of this kind. In this work, with reference to an isotactic polypropylene, some spiral flow tests obtained with different mold temperatures and injection pressures are analyzed with a twofold goal: on one side, to obtain from a few simple tests the basic rheological parameters of the material; on the other side, to suggest a method for a quick prediction of the final flow length.

Viscosity model based on equations of state for hydrocarbon liquids and gases

1997 ◽  
Vol 139 (1-2) ◽  
pp. 405-421 ◽  
Author(s):  
X.-Q. Guo ◽  
L.-S. Wang ◽  
S.-X. Rong ◽  
T.-M. Guo
Keyword(s):  
Equations Of State ◽  
Viscosity Model ◽  
Model Based

A New Extensional Viscosity Model Based on the Cross Model for Polymer Fluids

2011 ◽  
Vol 415-417 ◽  
pp. 2105-2108
Author(s):  
Lei Zhong ◽  
Hai Hang Xu ◽  
Ji Zhao Liang ◽  
An Ping Liao
Keyword(s):  
Extensional Viscosity ◽  
Viscosity Model ◽  
Extension Rate ◽  
Experiment Data ◽  
Cross Model ◽  
Polymer Fluids ◽  
Model Based ◽  
Proposed Model ◽  
Measurement Results ◽  
The Cross

A new extensional viscosity model based on the Cross model is introduced. The proposed model can correctly describe the relation between extensional viscosity and extension rate. Effect of the four parameters in the new model is analyzed in detail. Compare the predictive curves to the measurement results reported in the references. It shows that the model calculation gives a good fit to the experiment data. This simple model has only a few parameters and is easy to use.

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