An Analysis of the Casting Polymer Mold Wear Manufactured Using PolyJet Method Based on the Measurement of the Surface Topography

An important factor having an impact on the condition of machine parts is their surface topography. For instance, in the production of a molded element in casting or injection molding processes, the surface topography of the molding cavity has a significant impact on the surface condition of the product. An analysis of the wear of a mold made with the PolyJet technique was performed in this work, and we examined the surface topography using the stylus method after casting a wax model of the turbine blade. The surface topographies showed a gradual degradation of the mold cavity surface. After the manufacture of 40 castings, there was a significant deformation of the microstructure of the mold cavity. The maximum height value (Sz) parameter had the most dynamic change from 18.980 to 27.920 μm. Its growth dynamics are mainly influenced by maximum peak height (Sp) rather than the maximum pit height (Sv) parameter. In the case of the root mean square height (Sq) and arithmetic mean height (Sa), their gradual increases can be seen from 2.578 to 3.599 μm and from 2.038 to 2.746 μm. In the case of the value of the skewness (Ssk) parameter, a small positive skew was observed. As for the kurtosis (Sku) values, the distributions are clearly leptokurtic.

Tunable shape memory polymer mold for multiple microarray replications

Shape memory polymer-based microarray with tunable wettability is fabricated, which can be employed as a smart mold for microstructure replications.

Metal Injection Molding Process Parameters as A Function of Filling Performance of 3D Printed Polymer Mold

Metal injection molding (MIM) is a swift manufacturing process, which can produce complex and intricate parts with good repeatability and accuracy. However, to quickly address low-volume demands of customized MIM parts, manufacturing of mold could be a potential challenge. Typically, machined metal molds are used for MIM, but they are expensive and need more lead time. The machined metal mold becomes useless once the design is changed or requirement of MIM parts is met. Therefore, for MIM production of a low volume of highly customized parts, machined metal mold could be substituted by 3D printed polymer molds. However, knowledge of filling behavior of MIM feedstock in polymer mold is a grey area, which demands study to investigate the effects of injection parameters on mold filling. The present study investigates the effects of machine injection parameters on feedstock filling behavior in 3D printed polymer molds. An attempt has been made to determine the trend of feedstock filling in the polymer mold as a function of injection parameters. Further, the design of experiment (DOE) has been used to estimate the weight of injection parameters.

Fabrication of Metallic Nanodot Arrays Using Nano-Chemical Stamping Technique with a Polymer Stamp

The aim of this study is to develop metallic nanodot arrays with controlled morphology and alignment. To produce gold nanodot arrays with high throughput, the authors propose a new efficient fabrication process based on the templated thermal dewetting method, using a nano-chemical stamping technique with a polymer mold. This process comprises four steps: sputter etching on a quartz glass substrate, patterning of micrometer size by printing with acetone on the substrate by stamping with a polymer film stamp, deposition of a thin Au film on the substrate, and self-organization of the metal nanodot arrays by thermal dewetting. A new method, using a cyclo-olefin polymer film mold for chemical patterning by nano-chemical stamping, was examined. Since the acetone stamped on the substrate reduces the surface energy and affects the contact angle of the gold nanodots, the gold nanodots are distributed along the stamped pattern. It is found that the pattern stamped with acetone on the substrate works as a template for the thermal dewetting process. The nano-chemical stamping technique is useful in controlling the size and distribution of the nanodots.

Efficient Fabrication Process of Metal Nanodot Arrays Using Direct Nanoimprinting Method with a Polymer Mold

A new fabrication process of metal nanodot arrays using the thermal dewetting method was developed in this study. This process was comprised of three steps: thin Au film deposition on a quartz glass substrate, groove patterning by direct nanoimprinting, and self-organization of metal nanodot arrays by thermal dewetting. A new idea to utilize a polymer film mold for groove patterning by direct nanoimprinting was examined. The polymer film mold was prepared by hot-embossing groove patterns of a mother mold on a cyclo olefin polymer (COP) film. The mother mold was prepared from a silicon wafer. The polymer film mold was used for direct nanoimprinting on a metal film deposited on a quartz substrate. The experimental results revealed that the COP film mold can effectively form a micro groove pattern on the Au film despite the COP film mold being softer than the Au film. The micro groove on the Au film was also found to be effective in aligning the nanodots in lines. The micro groove patterning using the COP film mold was also confirmed to be useful in controlling the dot size and alignment during the thermal dewetting process.