scholarly journals Hybrid Process Chain for the Integration of Direct Ink Writing and Polymer Injection Molding

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 509 ◽  
Author(s):  
Dario Loaldi ◽  
Leonardo Piccolo ◽  
Eric Brown ◽  
Guido Tosello ◽  
Corey Shemelya ◽  
...  

The integration of additive manufacturing direct-writing technologies with injection molding provides a novel method to combine functional features into plastic products, and could enable mass-manufacturing of custom-molded plastic parts. In this work, direct-write technology is used to deposit conductive ink traces on the surface of an injection mold. After curing on the mold surface, the printed trace is transferred into the plastic part by exploiting the high temperature and pressure of a thermoplastic polymer melt flow. The transfer of the traces is controlled by interlocking with the polymer system, which creates strong plastic/ink interfacial bonding. The hybrid process chain uses designed mold/ink surface interactions to manufacture stable ink/polymer interfaces. Here, the process chain is proposed and validated through systematic interfacial analysis including feature fidelity, mechanical properties, adhesion, mold topography, surface energy, and hot polymer contact angle.

2017 ◽  
Vol 8 ◽  
pp. 746-753 ◽  
Author(s):  
D. Landgrebe ◽  
V. Kräusel ◽  
A. Rautenstrauch ◽  
B. Awiszus ◽  
J. Boll ◽  
...  

2018 ◽  
Vol 145 ◽  
pp. 02006
Author(s):  
Margarita Natova ◽  
Ivan Ivanov ◽  
Sabina Cherneva ◽  
Maria Datcheva ◽  
Roumen Iankov

During conventional polymer injection molding, flow- and weld lines can arise at the molded parts caused by disturbed polymer melt flow when it crosses different parts of the equipment. Such processed plastic goods have discrete zones of inhomogeneities of very small dimensions. In order to stabilize the melt flow and to equalize dimensions of such defective products, an approach for pulse injection molding is applied during production of polymer packagings. Testing methods used for evaluation of macromechanical performance of processed polymer products are not readily applicable to estimate the changes in visual surface obtained during pulse injecting. To overcome this testing inconvenience the performance of processed packagings is evaluated by nanoindentation. Using this method, a quantitative assessment of the polymer properties is obtained from different parts of technological products.


Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1423
Author(s):  
Eva Oliveira ◽  
João Paulo Silva ◽  
Jorge Laranjeira ◽  
Francisco Macedo ◽  
Senentxu Lanceros-Mendez ◽  
...  

This paper presents the development of metallic thermoresistive thin film, providing an innovative solution to dynamically control the temperature during the injection molding process of polymeric parts. The general idea was to tailor the signal response of the nitrogen- and oxygen-doped titanium-copper thin film (TiCu(N,O))-based transducers, in order to optimize their use in temperature sensor devices. The results reveal that the nitrogen or oxygen doping level has an evident effect on the thermoresistive response of TiCu(N,O) films. The temperature coefficient of resistance values reached 2.29 × 10−2 °C−1, which was almost six times higher than the traditional platinum-based sensors. In order to demonstrate the sensing capabilities of thin films, a proof-of-concept experiment was carried out, integrating the developed TiCu(N,O) films with the best response in an injection steel mold, connected to a data acquisition system. These novel sensor inserts proved to be sensitive to the temperature evolution during the injection process, directly in contact with the polymer melt in the mold, demonstrating their possible use in real operation devices where temperature profiles are a major parameter, such as the injection molding process of polymeric parts.


Author(s):  
M. Tutar ◽  
A. Karakus

In the present study a more complete numerical solution approach using parallel computing technology is provided for the three-dimensional modeling of mold insert polymer injection molding process by considering the effects of phase-change and compressibility for non-Newtonian fluid flow conditions. A volume of fluid (VOF) method coupled with a finite volume approach is used to simulate the mold-filling stage of the injection molding process. The variations in viscosity and density in the polymer melt flow are successfully resolved in the present VOF method to more accurately represent the rheological behavior of the polymer melt flow during the mold filling. A comprehensive high-resolution differencing scheme (compressive interface capturing scheme for arbitrary meshes or CICSAM) is successfully utilized to capture moving interfaces and the pressure-implicit with splitting operators pressure-velocity coupling algorithm is employed to enable a higher degree of approximate relation between corrections for pressure and velocity. The capabilities of the proposed numerical methodology in modeling real molding flow conditions are verified through quantitative and qualitative comparisons with other simulation programs and the data obtained from the experimental study conducted. The present numerical results are also compared with each other for a polypropylene female threaded adaptor pipe fitting model with a metallic insert for varying governing process conditions/parameters to assess the modeling constraints and enhancements of the present numerical procedure and the effects of these conditions to optimize the polymer melt flow for mold insert polymer injection molding process. The numerical results suggest that the present numerical solution approach can be used with a confidence for further studies of optimization of design of mold insert polymer injection molding processes.


Author(s):  
E. B. Brousseau ◽  
F. Krohs ◽  
E. Caillaud ◽  
S. Dimov ◽  
O. Gibaru ◽  
...  

The continuing trend for producing novel micro- and nanostructured devices and components in a broad range of materials is a major motivating factor driving the research in the micro- and nanomanufacturing sector toward developing innovative process chains. Some of such chains enable the serial production of micro- and nanostructured parts in polymer material by combining innovatively and optimizing simultaneously master making and replication technologies. For producing features at the nanoscale, the master making processes that are currently commonly employed rely on complex lithography-based pattern transfers and/or on beam-based direct write processes. Unfortunately, the required equipment to perform these techniques are often capital intensive and necessitate particular operating temperatures or vacuum conditions. At the same time, during the development phase of new or improved nanotechnology-enabled products, it is beneficial to produce rapidly polymer prototypes to test the functionality of components with nanoscale features. Thus, the technologies currently available for nanostructuring replication masters do not comply with the low cost requirements typically associated with the production of small batches of components for prototyping purposes. As a result, this could restrict the successful development of products with functional features at the nanoscale. In this research, a new process chain is presented for the fabrication of nanostructured components in polymer that relies on a simple and cost-effective master making technology. In particular, atomic force microscopy scratching is employed as an alternative technique for nanostructuring replication masters for microinjection molding. The conducted experimental study demonstrated the potential of this approach for small and medium series production of nanostructured devices in thermoplastic materials. In addition, the effects of different scratching parameters on the achievable surface roughness and depth of the patterned structures were analyzed by employing the design of experiments approach.


1994 ◽  
Vol 34 (8) ◽  
pp. 671-679 ◽  
Author(s):  
Anthony J. Bur ◽  
Francis W. Wang ◽  
Charles L. Thomas ◽  
Joseph L. Rose

2020 ◽  
Author(s):  
Zachary G. Davis ◽  
Aasim F. Hussain ◽  
Matthew B. Fisher

AbstractSeveral biofabrication methods are being investigated to produce scaffolds that can replicate the structure of the extracellular matrix. Direct-write, near-field electrospinning of polymer solutions and melts is one such method which combines fine fiber formation with computer-guided control. Research with such systems has focused primarily on synthetic polymers. To better understand the behavior of biopolymers used for direct-writing, this project investigated changes in fiber morphology, size, and variability caused by varying gelatin and acetic acid concentration, as well as, process parameters such as needle gauge and height, stage speed, and interfiber spacing. Increasing gelatin concentration at a constant acetic acid concentration improved fiber morphology from large, planar structures to small, linear fibers with a median of 2.3 µm. Further varying the acetic acid concentration at a constant gelatin concentration did not alter fiber morphology and diameter throughout the range tested. Varying needle gauge and height further improved the median fiber diameter to below 2 µm and variability of the first and third quartiles to within +/-1 µm of the median for the optimal solution combination of gelatin and acetic acid concentrations. Additional adjustment of stage speed did not impact the fiber morphology or diameter. Repeatable interfiber spacings down to 250 µm were shown to be capable with the system. In summary, this study illustrates the optimization of processing parameters for direct-writing of gelatin to produce fibers on the scale of collagen fibers. This system is thus capable of replicating the fibrous structure of musculoskeletal tissues with biologically relevant materials which will provide a durable platform for the analysis of single cell-fiber interactions to help better understand the impact scaffold materials and dimensions have on cell behavior.


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