Flow instability of semicrystalline polymer melt during micro-injection molding

2014 ◽  
Vol 24 (8) ◽  
pp. 085015 ◽  
Author(s):  
Sun Kyoung Kim ◽  
Dae-Jin Kim ◽  
Jae Sung Jung ◽  
Younghak Cho
Keyword(s):  
Injection Molding ◽  
Flow Instability ◽  
Polymer Melt ◽  
Semicrystalline Polymer ◽  
Micro Injection Molding

An Investigation into the Influencing Factors for Polymer Melt at the Filling Stage in Micro Injection Molding

2013 ◽  
Vol 562-565 ◽  
pp. 1380-1386
Author(s):  
Jian Zhuang ◽  
Da Ming Wu ◽  
Ya Jun Zhang ◽  
Lin Wang ◽  
Xiong Wei Wang ◽  
...  
Keyword(s):  
Injection Molding ◽  
Influencing Factors ◽  
Polymer Melt ◽  
Theoretical Models ◽  
Injection Molding Process ◽  
Melt Flow ◽  
Molding Process ◽  
Micro Injection Molding ◽  
Filling Stage ◽  
Conventional Injection Molding

The flow behaviors for polymer melt at the filling stage in micro injection molding are different from those in conventional injection molding due to the miniaturization of plastic parts. This paper focuses on the study of the effects of three main influencing factors, including the microscale viscosity and wall slip, on melt filling flow in microscale neglected those in conventional injection molding process. The theoretical models and the interrelation of these factors in microscale channels were constructed by means of the model correction method. Then, the micro melt flow behaviors were investigated with comparisons of the available experimental data. The results indicate that the dimensions affect the shear rates and viscous dissipation, which in turn affects the apparent viscosity. Finally, the conclusion is that the melt flow behaviors in microchannels are different from those in macrochannels owing to these significant influencing factors.

Effects of Wall Slip on Filling Flow for Polymer Melt in Micro Injection Molding

2014 ◽  
Vol 609-610 ◽  
pp. 617-622 ◽  
Author(s):  
Jian Zhuang ◽  
Ya Jun Zhang ◽  
Da Ming Wu ◽  
Li Zhu Liu ◽  
Cheng Jun Sun ◽  
...  
Keyword(s):  
Injection Molding ◽  
Slip Velocity ◽  
Polymer Melt ◽  
Wall Slip ◽  
Diameter Ratio ◽  
Micro Injection Molding ◽  
Slip Mechanism ◽  
Inlet Flow Rate ◽  
Section Size ◽  
Slip Coefficients

Effect of wall slip on melt filling flow behaviors in micro injection molding are investigated based on analysis of wall slip mechanism for polymer melt flowing at filling stage. By means of comparisons, slip coefficients in different microchannels are confirmed. With finite element method, the relationship between slip velocity and inlet flow rate or length-diameter ratio is analyzed. The results indicate that the wall slip happen for polymeric melt in microchannels, and slip coefficients are related with the size characteristics of microchannels. Moreover, wall slip velocity has the size effect and increase with the decrease of the section size of microchannels, which cause melt velocity distribution to smooth. At the same time, slip velocity is proportional to length-diameter ratio of microchannel, namely when wall shear stress is uniform, the slip velocity rises with increasing length-diameter ratio of microchannel.

The Method of Improving Precision of Micro Injection Molding Machine Temperature Control

2013 ◽  
Vol 372 ◽  
pp. 354-359
Author(s):  
Sheng De Tang ◽  
Hong Xu ◽  
Da Ming Wu ◽  
Ya Jun Zhang
Keyword(s):  
Injection Molding ◽  
Temperature Control ◽  
Control Method ◽  
Polymer Melt ◽  
Molding Machine ◽  
Micro Injection Molding ◽  
Injection Molding Machine ◽  
Mathematical Algorithm ◽  
Accurate Temperature ◽  
Accurate Temperature Control

the temperature control accuracy of polymer melt is the main factor affecting quality precision of final products. In this paper, we study the method of improving the precision of temperature control based on control system of micro injection molding machine. In order to avoid big overshoot in the traditional PID control, we use gradual approximation control method based on gradual approximation mathematical algorithm to realize fast and accurate temperature control of the micro injection molding machine. Experiment results show that effective combination of the traditional PID and gradual approximation method can realize accurate temperature control of micro injection molding machine, and precision of temperature control can be improved up to±0.5°C.

Plastic Micro Features Produced by Microwelding Machine

2011 ◽  
Vol 328-330 ◽  
pp. 1453-1456
Author(s):  
Hang Liu ◽  
Yan Xu ◽  
Kei Leung Yung ◽  
C.L. Kang ◽  
W. Tian
Keyword(s):  
Stainless Steel ◽  
Injection Molding ◽  
Polymer Melt ◽  
Micro Injection Molding ◽  
Micro Features

The method of using microwelding machine to fabricate micro features on a stainless steel micro mould has been studied. The micro features obtained from molding using an ultrasonic microwelding machine have shown distinctive characteristics. The microflow behavior of polymer melt during the microwelding process is also studied. The micro molds of 0.2mm thick and through holes of 0.05mm and 0.2mm in diameters were used. Results show micro features can be produced using the microwelding machine with molding speed comparable to that of micro injection molding.

Flows in Microchannels and Cavities – Visco-Elasticity, Faradaic Charging and Surface Roughness Effects

2009 ◽  
Vol 74 ◽  
pp. 73-76
Author(s):  
Yee Cheong Lam
Keyword(s):  
Surface Roughness ◽  
Injection Molding ◽  
Flow Model ◽  
Flow Instability ◽  
Polymer Melt ◽  
Injection Molding Process ◽  
Elastic Instability ◽  
Molding Process ◽  
Roughness Effects ◽  
Plastic Injection

Two phenomena for flows in microchannels, namely visco-elastic instability and Faradaic charging effects, are discussed. Aqueous solutions, which do not exhibit elastic behaviors, will behave visco-elastically with the addition of a small amount of polymers. Visco-elastic flow instability which promote mixing has been observed in the flow of these visco-elastic solutions through a constriction in microchannels. In addition, we recently show experimentally the existance of Faradaic charging in AC-electrokinetic (ACEK) flow. Lastly, surface roughness effects in micro- plastic injection molding are highlighted. The micro-injection molding process involves the flow of polymer melt in micro-cavities. Our recent investigations demonstrate that the flow model for macro-cavities could be employed satisfactorily to simulate the flow in micro-cavities if roughness effects are considered in an appropriate manner.

Sign in / Sign up

Export Citation Format

Share Document