Med-Tech Innovation Micro moulding
Pioneering Micro Moulding TECHNOLOGY
Enric Sirera of Ultrasion describes novel ultrasonics-based micro moulding technology that provides a cost-effective alternative to traditional micro injection manufacturing and opens up numerous areas of product innovation previously considered impossible.
A
s the demand for miniaturisation of parts and components has grown, a number of companies have invested in producing injection moulding machines specifi cally for
the production of micro parts. Micro injection moulding as a production technology has been welcomed by industry as a means to achieve volume manufacture of micro plastic parts at what has been considered until recently a relatively low cost. Whether micro or macro, injection moulding works using the same principles. Raw material in the form of plastic pellets is placed in a hopper, melted in a screw and barrel, and then injected into the mould.
The art of micro moulding It has long been recognised that various parameters alter the effectiveness of micro injection moulding, including the melt temperature of the material to be injected, the injection speed and pressure, and tool surface quality that can adversely affect fl ow characteristics. In addition, because the technology is scaled down
from macro injection moulding technologies, it exhibits many of the drawbacks of its larger cousin: it is highly energy ineffi cient (with the need for permanent heating
16 ¦ September/October 2014
of the screw and barrel using heater bands running continuously at 1.7 kW/h), and wasteful of material (melting much more material than is necessary for actual manufacture of parts), and it employs expensive tooling due to the high moulding pressures that are required. Material wastage is exacerbated in micro applications, in some instances less than 10% of material melted is actually used and the remainder needs to be purged from the machine and discarded. In medical applications where the cost of raw materials is often extremely high this wastage is of great signifi cance. Add to this the fact that as micro injection moulding machines are developed from a macro technology that is reduced in size to fit micro applications, it is disproportionately complicated and uses a number of peripherals to manufacture effectively. Thus, this seemingly cost-effective micro manufacturing technology does not look so cost-effective after all.
An alternative approach A new approach to micro moulding was recently commercialised by Barcelona-based company Ultrasion. This new technology harnesses ultrasonics in the micro
www.med-techinnovation.com
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