Abstract. The development of MEMS and Microsystems needs a reliable massproduction process to fabricate micro components with micro/nano scale features. In our study, we used the micro injection molding process to replicate micro/nano scale channels and ridges from a Bulk Metallic Glass (BMG) cavity insert. High density polyethylene (HDPE) was used as the molding material and Design of Experiment (DOE) was adopted to systematically and statistically investigate the relationship between machine parameters, real process conditions and replication quality. The peak cavity pressure and temperature were selected as process characteristic values to describe the real process conditions that material experienced during the filling process. The experiments revealed that the replication of ridges, including feature edge, profile and filling height, was sensitive to the flow direction; cavity pressure and temperature both increased with holding pressure and mold temperature; replication quality can be improved by increasing cavity pressure and temperature within a certain range. The replication quality of micro/nano features is tightly related to the thermomechanical history of material experienced during the molding process. In addition, the longevity and roughness of the BMG insert was also evaluated based on the number of injection molding cycles.
Human beings have witnessed unprecedented developments since the 1760s using precision tools and manufacturing methods that have led to ever-increasing precision, from millimeter to micrometer, to single nanometer, and to atomic levels. The modes of manufacturing have also advanced from craft-based manufacturing in the Stone, Bronze, and Iron Ages to precisioncontrollable manufacturing using automatic machinery. In the past 30 years, since the invention of the scanning tunneling microscope, humans have become capable of manipulating single atoms, laying the groundwork for the coming era of atomic and close-to-atomic scale manufacturing (ACSM). Close-to-atomic scale manufacturing includes all necessary steps to convert raw materials, components, or parts into products designed to meet the user's specifications. The processes involved in ACSM are not only atomically precise but also remove, add, or transform work material at the atomic and close-to-atomic scales. This review discusses the history of the development of ACSM and the current state-of-the-art processes to achieve atomically precise and/or atomic-scale manufacturing. Existing and future applications of ACSM in quantum computing, molecular circuitry, and the life and material sciences are also described. To further develop ACSM, it is critical to understand the underlying mechanisms of atomic-scale and atomically precise manufacturing; develop functional devices, materials, and processes for ACSM; and promote high throughput manufacturing.
A bstract: In-line process monitoring and rheological characterization can help to understand the behavior of polymer melt flows during manufacturing and to make injection molding a measurable process for manufacturing high quality parts. This work developed an in-line rheology measurement system using a slit die attached to a micro injection molding machine. A series of dog-bone mold inserts was used to form the slit die with thickness ranging from 600µm to 200µm. Two combined pressure and temperature sensors were embedded into the slit die to measure the pressure drop. Based on the slit flow model, it was found that the viscosity of Pebax melts depends on the slit thickness in the actual injection molding process. The competing effects of wall slip and non-isothermal conditions will determine the melt viscosity. The plastication induced thermo-mechanical history can also influence polymer viscosity, although it is neglected in conventional rheology measurements.
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