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Reinventing micro- and nanomoulding: recent advances in micro- and nanomoulding techniques are expanding the possibilities in polymer processing. New materials and ever more demanding end uses have prompted a structured rethink of many of the traditional "rules" and led to novel processing and measurement developments that are crucial for successful industrial exploitation of micromoulding.

Article Excerpt
Micromoulding defined

Microinjection moulding (micromoulding) is not directly comparable with conventional injection moulding. The product dimensions can be extremely small (weights of approximately 1 milligram are typical), and the thermal and flow conditions within a micromoulding process are significantly different from the conventional injection moulding process, from which the technology was derived. Product surface areas are large compared with product volumes. This results in rapid heat loss from the molten material as the cavity fills and requires high injection speeds to avoid premature solidification and incomplete products. This high-speed injection can also cause stresses and strain rates in the material that are orders of magnitude higher than those found in conventional injection moulding and result in unusual material integrity and morphology. These factors mean that the operating window is small and process variations, temperature fluctuations, material inconsistency and ingress of impurities can result in substandard products that will not function in the manner for which they were designed. These factors pose interesting challenges for process measurement and control, which are required to create a successful manufacturing system.

The first large-scale production of micromouldings began in the late 1980s. A number of subsequent enabling technologies provided the processing and measurement facilities that are essential for this specialised area of production. The processing requirements have led to the development of a number of dedicated moulding machines. Some are described below and have adopted different approaches:

* A servo electric micromoulding machine from Battenfeld (www. battenfeld.co.uk) has a three-stage...

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