Effect of micro tensile sample’s cross section shape on the strength of weld line in micro injection molding process

2009 ◽  
Vol 15 (7) ◽  
pp. 1031-1037 ◽  
Author(s):  
Lei Xie ◽  
Gerhard Ziegmann ◽  
Marcus Hlavac ◽  
Ronald Wittmer
2016 ◽  
Vol 4 (2) ◽  
Author(s):  
Seong Ying Choi ◽  
Nan Zhang ◽  
J. P. Toner ◽  
G. Dunne ◽  
Michael D. Gilchrist

Vacuum venting is a method proposed to improve feature replication in microparts that are fabricated using micro-injection molding (MIM). A qualitative and quantitative study has been carried out to investigate the effect of vacuum venting on the nano/microfeature replication in MIM. Anodized aluminum oxide (AAO) containing nanofeatures and a bulk metallic glass (BMG) tool mold containing microfeatures were used as mold inserts. The effect of vacuum pressure at constant vacuum time, and of vacuum time at constant vacuum pressure on the replication of these features is investigated. It is found that vacuum venting qualitatively enhances the nanoscale feature definition as well as increases the area of feature replication. In the quantitative study, higher aspect ratio (AR) features can be replicated more effectively using vacuum venting. Increasing both vacuum pressure and vacuum time are found to improve the depth of replication, with the vacuum pressure having more influence. Feature orientation and final sample shape could affect the absolute depth of replication of a particular feature within the sample.


Author(s):  
Carlos Rodríguez-Mondéjar ◽  
Álvaro Rodríguez-Prieto ◽  
Ana María Camacho

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.


2010 ◽  
Vol 156-157 ◽  
pp. 1141-1145
Author(s):  
Ben Ma ◽  
Hai Qing Li ◽  
Xu Deng ◽  
Min Li

Expandable cased-hole liners is to solve the sealing problem of level six multilateral wells. It is a trigeminal expandable tube which is usually prefabricated on the ground and re-expanded when placed in the proper position. In this paper, the trigeminal expandable tubular compression molding process of the pre-forming stage is mainly studied. In this compression process, both sides of the branch pipe should be compressed to a certain shape in order to successfully enter the main borehole; meanwhile, we want to make sure that failures such as rupture do not occur in the subsequent expansion process. According to the theory about sheet metal bending forming process, three different shapes of the mold are designed to control the cross-section shape of the compressed trigeminal expandable tube so that it meets the application requirements. Rack-shaped cross-section is finally selected as a reference of the best through simulation of compression process and comparative analysis of simulation results. At last, field tests show that this cross-section shape is compatible with the theoretical and simulation results.


Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 614 ◽  
Author(s):  
Dario Loaldi ◽  
Francesco Regi ◽  
Federico Baruffi ◽  
Matteo Calaon ◽  
Danilo Quagliotti ◽  
...  

The increasing demand for micro-injection molding process technology and the corresponding micro-molded products have materialized in the need for models and simulation capabilities for the establishment of a digital twin of the manufacturing process. The opportunities enabled by the correct process simulation include the possibility of forecasting the part quality and finding optimal process conditions for a given product. The present work displays further use of micro-injection molding process simulation for the prediction of feature dimensions and its optimization and microfeature replication behavior due to geometrical boundary effects. The current work focused on the micro-injection molding of three-dimensional microparts and of single components featuring microstructures. First, two virtual a studies were performed to predict the outer diameter of a micro-ring within an accuracy of 10 µm and the flash formation on a micro-component with mass a 0.1 mg. In the second part of the study, the influence of microstructure orientation on the filling time of a microcavity design section was investigated for a component featuring micro grooves with a 15 µm nominal height. Multiscale meshing was employed to model the replication of microfeatures in a range of 17–346 µm in a Fresnel lens product, allowing the prediction of the replication behavior of a microfeature at 91% accuracy. The simulations were performed using 3D modeling and generalized Navier–Stokes equations using a single multi-scale simulation approach. The current work shows the current potential and limitations in the use of micro-injection molding process simulations for the optimization of micro 3D-part and microstructured components.


Author(s):  
Vincenzo Bellantone ◽  
Fulvio Lavecchia ◽  
Rossella Surace ◽  
Onofrio Spadavecchia ◽  
Francesco Modica ◽  
...  

Abstract Micro applications, especially in biomedical and optical sectors, require the fabrication of thin polymeric parts which can be commonly realized by micro injection molding process. However, this process is characterized by a relevant constraint regarding the tooling. Indeed, the design and manufacturing of molds could be a very time-consuming step and so, a significant limitation for the rapid development of new products. Moreover, if the design displays challenging micro-features, their realization could involve the use of more than one mold for the fabrication of a single thin part. Therefore, a proper integration of different manufacturing micro technologies may represent an advantageous method to realise such polymeric thin micro features. In this work, a micro-manufacturing process chain including stereolithography, micro milling and micro injection molding is reported. The mold for the micro injection molding process was fabricated by means of stereolithography and micro milling, which allowed to produce low-cost reconfigurable modular mold, composed by an insert support and a removable insert. The assessment of the proposed process chain was carried out by evaluating the dimensions and the surface finishing and texturing of the milled mold cavities and molded components. Finally, a brief economic analysis compares three process chains for fabricating the micro mold showing that proposed one reduces manufacturing cost of almost 61% with the same production time.


2013 ◽  
Vol 562-565 ◽  
pp. 1380-1386
Author(s):  
Jian Zhuang ◽  
Da Ming Wu ◽  
Ya Jun Zhang ◽  
Lin Wang ◽  
Xiong Wei Wang ◽  
...  

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.


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