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Cera Dynamics Ltd had relied for many years on a manual mixing system for
their research and quality control of specialist glass powders, but
embarked on a search for a process solution that would be more effective,
more consistent, quicker and simpler. The glass powders produced by Cera
Dynamics are tailored to customer need - primarily for dental fillers and
restorers, they vary from 0.5 to 10 microns average particle size. For
testing purposes the glass powder needs to be mixed with a high viscosity
acrylic resin monomer to check for high transparency and low
discolouration - but the manual process, while well understood, continued
to give problems of non-homogeneity and air inclusion, both of which
preclude colour checking of the glass.
The search for an improved system led Dr Philip Frampton to the industry
standard vacuum mix machine - excellent for 100 to 200g but not suitable
for 10g samples - also to a purely planetary mixer which was found to
enfold too much air - and ultimately to the new Thinky ARE-250 from
Intertronics, which incorporates both planetary mixing and centrifugal
degassing in one unit.
Tests with the Thinky equipment involved mixing 60% glass with 40%
acrylic by weight in viscosities varying from “thick honey to stiff
bubble gum,” according to Dr Frampton. Empirical investigation supported
by advice from the Intertronics engineers rapidly determined suitable
program parameters based on viscosity and these samples were then pressed
and cured into standard £2 coin sized discs for comparison with
established colour standards.
Dr Frampton explained “Cera Dynamics are one of probably only 4 or 5
companies in the world operating at the top level in this technology and
we were looking to improve the mixing stage as a first step to overall
improvement of our glass grinding process. Intertronic’s expertise and
supply of the Thinky mixer has allowed us to achieve that initial goal in
a single operation - so now we have a reliable quality control process we
can move to purchase of a spectro-photometer. This will enable us to
refine our operation further toward development of an even cleaner and
finer grinding process.”
The Thinky ARE-250 Mixer allows for the process of mixing and bubble
removal to be carried out simultaneously. It mixes, disperses and
degasses materials in seconds to minutes, in a sealed or lid-less
container such as a jar, beaker, syringe barrel, or cartridge. The non-
contact mixing principle makes it possible for formulation of compounds
from very small amounts such as 0.5ml to production quantities of 310g.
The ARE-250 may be used to formulate and mix adhesives, sealants,
moulding compounds, lubricants, slurries, coatings, inks, paints,
abrasives, bio chemicals, cements, medical compounds, cosmetics/personal
care materials, detergents, conductive pastes, dental materials, foods,
construction materials or any other materials which are hard-to-mix, hard-
to-degass, or hard-to-wet.
The Thinky ARE-250 Mixer works by revolving and rotating the container in
a planetary manner at various speeds with both overall and planetary
rotational speeds independently pre-programmable. Centrifugal force
presses the material outwards to the inner wall of the container. Other
forces cause the material to move downwards in a spiralling direction
along the slope of container wall. The material then moves back to the
centre of the container and up to the top. As a result, material
circulation from top to the bottom generates kneading effects, forcing
trapped air out of the material.
This ensures no cross-contamination between batches, no damage to
material from rollers, mixing blades or propellers and no unit cleaning
between batches, as well as allowing re-mixing of separated materials to
prolong shelf life. Consequently, process cycles may be reduced, lowering
costs and improving yield rates. The whole non-contact programmable
approach greatly improves consistency of quality and improves formulation
irrespective of operator skill levels. Further information regarding
Intertronics’ products can be found at www.intertronics.co.uk
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