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centrifugal type force onto the materials, for mixer with an integral vacuum to achieve more
dedicated air removal. This is normally followed by thorough degassing. Mixing under vacuum will
another period of mixing mode to recombine the ensure that there is no air entrapment, even of very
materials evenly. small bubbles. Highly viscous materials are more
Planetary centrifugal mixers can bring numerous readily degassed under vacuum. Users of specialist
benefits to manufacturers. Because the process optical materials or potting compounds for very high
does not have to use dedicated containers and is voltage applications cannot accept micro-bubbles in
non-contact (there are no mechanical stirrers in the their critical projects. The use of a vacuum mixer
materials), cleaning requirements are much reduced will often preclude the need for a separate vacuum
and the risk of cross-contamination is minimal. degassing process.
Precise and repeatable control of the process
makes it possible to improve formulation quality, Case in point
eliminate human error and reduce variations that One example of a company using a vacuum mixer is
occur due to operator skill. It is effective in LED manufacturer Plessey Semiconductors, which
controlling shear, so as not to damage your transitioned from manufacturing development to full
materials — unlike the use of rollers, mixing blades production by employing automated mixing and
or propellers. dispensing technologies. The company opted for a
Thinky ARV-310 LED benchtop mixer to remove air
Choose your type while homogenously mixing heavy fillers into
The combined mixing and degassing modes of the liquids, including phosphor.
standard Thinky mixers, which operate under Mixing is required for a broad range of
ambient pressure, will usually mix materials so that applications and materials, but each one requires a
there is no visible sign of bubbles. carefully considered approach. By working with an
In applications where even micro-bubbles experienced adhesives supplier, you can select the
(perhaps on the order of 100μm diameter) cannot most appropriate equipment for your process.
be tolerated, manufacturers may want to consider a www.intertronics.co.uk

May 2020 • INDUSTRIAL TECHNOLOGY EXTRA! • p19