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.

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.

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.

scholarly journals Online Rheometry Investigation of Flow/Slip Behavior of Powder Injection Molding Feedstocks

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 432 ◽  
Author(s):  
Daniel Sanetrnik ◽  
Berenika Hausnerova ◽  
Vladimir Pata
Keyword(s):  
Surface Roughness ◽  
Injection Molding ◽  
Slip Velocity ◽  
Wall Slip ◽  
Powder Injection Molding ◽  
Water Soluble ◽  
Powder Injection ◽  
Powder Particle Size ◽  
Slip Effect ◽  
Rectangular Slit

Wall slip in the flow of powder injection molding (PIM) compounds can be the cause of unrealistically low viscosity values, and can lead to a failure of flow simulation approaches. Regardless of its importance, it has been considered only scarcely in the rheological models applied to PIM materials. In this paper, an online extrusion rheometer equipped with rectangular slit dies was used to evaluate the slip velocity of commercial as well as in-house-prepared PIM feedstocks based on metallic and ceramic powders at close-to-processing conditions. The tested slit dies varied in their dimensions and surface roughness. The wall-slip effect was quantified using the Mooney analysis of slip velocities. The smaller gap height (1 mm) supported the wall-slip effect. It was shown that both the binder composition and the powder characteristic affect slip velocity. Slip velocity can be reduced by tailoring a powder particle size distribution towards smaller particle fractions. The thickness of the polymer layer formed at the channel wall is higher for water-soluble feedstocks, while in the case of the catalytic polyacetal feedstocks the effect of surface roughness was manifested through lower viscosity at smooth surfaces.

Wall Slip of Linear Polymer Melts During Ultrasonic-assisted Micro-injection Molding

2018 ◽  
Vol 59 (S1) ◽  
pp. E7-E13 ◽  
Author(s):  
Shan Gao ◽  
Zhongjun Qiu ◽  
Junhao Ouyang ◽  
Yujun Yang
Keyword(s):  
Injection Molding ◽  
Polymer Melts ◽  
Wall Slip ◽  
Linear Polymer ◽  
Micro Injection Molding ◽  
Ultrasonic Assisted
Sign in / Sign up

Export Citation Format

Share Document