Feasibility study of thin microinjection molded components

Abstract

The trend toward the miniaturization of parts has created a strong demand for the manufacturing of precision‐molded miniature polymeric components, due to their high productivity and cost‐effectiveness. The objective of this study is the investigation of the filling behavior and dimensional accuracy of thin microinjection‐molded components using chemical blowing agents and wood fibers. In order to investigate the dimensional stability of the miniature molded parts, a micromold was designed and manufactured using a precision micromilling machine. The flow pattern of the thin molded components was experimentally investigated using different materials: pure linear low‐density polyethylene (LLDPE), foamed LLDPE, and wood fiber LLDPE composite. The results indicate that viscosity significantly affects the flow patterns. Filling behavior of the molded parts was also investigated using commercial flow software. Dimensional accuracy and shrinkage of the molded parts were measured using various gauges. Controlling the cell size, cell density, and distribution of foamed parts was especially difficult for thin micro components; however, the results showed that use of chemical blowing agents can improve the flow ability of the thin components in the microinjection molding process. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

In situ nano-fibrillation of microinjection molded poly(lactic acid)/poly(ε-caprolactone) blends and comparison with conventional injection molding

“…The current study on microinjection molding technology in literatures was mainly focused on mold structure optimization, [7][8][9] melt owing and lling behavior in the micro-ow channel, [10][11][12][13] process parameters, 14 apparent quality and microstructure of micropart, [15][16][17][18][19] etc. However, the investigations of the properties (especially mechanical performance) of microinjection molding products are relatively less involved, which is possibly related to the too small dimension of the microparts.…”

Microinjection molding of microsystem components: new aspects in improving performance

“…The presence of reinforcements often raises the melt viscosity, which in turn increases the flow resistance. This is especially true in the case for micro-channels having comparable dimensions with the fillers [27]. Unexpectedly, experimental evidence shows that conventional fillers are able to enter micro-channels as easily as they do a macro-cavity [158].…”

Replicability of Ultrasonic Molding for Processing Thin-Wall Polystyrene Plates with a Microchannel

“…Some reasons for this strong tendency include the reduced weight of the component, the increment of the complexity of 3D geometries, the trend toward miniaturization of parts, the increment of functionality of products, the high performance requirement of the materials, and the emergence of many new polymers with very different characteristics [1,2]. …”

“…In recent years, the use of polymer materials in industry has increased notably, with sectors such as micro-electromechanical systems (MEMS), aeronautics, and biomedicine slightly influenced by this trend. Some reasons for this strong tendency include the reduced weight of the component, the increment of the complexity of 3D geometries, the trend toward miniaturization of parts, the increment of functionality of products, the high performance requirement of the materials, and the emergence of many new polymers with very different characteristics [ 1 , 2 ].…”

“…The replication accuracy improved for higher mold temperature and thinner part thickness, because the pressure of the melt inside the mold increased and the polymer could reach further. Mahmoodi et al [ 2 ] investigated the filling behavior and dimensional accuracy of a thin part (6 × 6 mm square, 200 µm thick) using microinjection molding and adding chemical blowing agents and wood fibers. Injection pressure and mold temperature were modified in both experiments and the numerical model obtained consistent results.…”