Page 19 - Industrial Technology July 2021

DESIGN ENGINEERING

functionalities. Some are pure mixing models, some Precision mixing contains costs
perform both mixing and removal of visible bubbles and
some can both mix and degas to a high level under an
integral vacuum — and removing micro-bubbles down to pre-pilot mixing plant is using wireless watery, cheap and ineffective; overly high viscosity and
100 microns diameter. Opting for a machine with more TorqSense transducers for ultra-accurate it is unpleasant and greasy.
functionalities than you need will increase upfront costs. viscosity measurement of high-value “There is an optimum point where the product feels
Assessing both the volume and frequency of the Acompounds. The plant is used to prepare small luxurious and high quality, which is what needs to be
mixing process are important in determining firstly which batches of compounds from shampoo and detergent to identified for each formulation. In the past this was done
mixer to invest in and which consumables you will need. cosmetics, therapeutic and medical preparations. Some manually, so was completely subjective and
A machine capable of mixing larger volumes will be more of the ingredients in the compounds are very expensive, unquantifiable: TorqSense has changed this to a precise
expensive, so it may be more cost effective to mix so product developers are loath to make large batches and scientific procedure.”
materials in smaller batch sizes. For example, if you are early in the formulation process. TorqSense is a wireless sensor, which is not
mixing 500g of material, splitting it into five batches that Instead, they start with 850 millilitre samples for the physically connected to the mixer shaft by slip rings.
fit into a smaller machine might offer better ROI. early stages of each project, then once the recipe is well- Instead, it monitors the torque via radio waves. A shaft
Weighing up all the indirect costs from the process, proven, move on to pilot-scale work where the samples deforms very slightly when it rotates, the amount of
labour and quality factors against the cost of the mixer are measured in thousands of litres. The final deformation being proportional to the
can help to determine the payback period and the ROI of stage is, of course, full-scale torque. TorqSense measures the
the equipment. Like all mixing processes, a THINKY production where volumes may deformation so that it
Mixer will require some ongoing expenditure in mixing be truly enormous. can calculate
containers. There is a trade-off of disposable versus The TorqSense transducers torque. To do this
reusable containers, remembering to were supplied by Sensor Tech- two tiny piezo-
factor in cleaning time for the latter. nology of Banbury, whose Mark electric combs are
For critical processes, the risk of Ingham explains the glued to the surface of the
cross contamination may mean design of the pre- shaft at right angles to one
you are required to use single use pilot plant: “It can another; shaft deformation
containers. The ultimate solution take three hours or will expand one comb
would be to mix in the final more to make a and compress the other.
packaging container, which is a single sample, each The radio frequency
feasible option if required. produced with precision accuracy – and signal emitted by the TorqSense
Mixer choice will depend on development programmes need a great is reflected back by the combs, with its
volume and features, that is to say many samples. Clearly this cannot be done frequency changed in proportion to the combs’
integral vacuum. A good supplier will manually. Automating the basic mixing process is in deformation.
have the ability to address your mixing principle straightforward; for this the plant has four “The procedure to set up the TorqSense is very
challenge by doing laboratory evaluations workstations based on paddle mixers, each of which is simple, says Mark. “Solution’s using other technologies
and demonstrations with you. Their previous monitored by a TorqSense.” would probably take several hours to set up. With a
experience will help you develop the best TorqSense constantly assesses the level of torque in regime of up to 30 tests per day, TorqSense is the only
combination of mixing parameters for an a driven shaft. Often, this is used to measure the power real solution for this plant.”
optimal outcome. being provided by the drive motor. However, in this case Other TorqSense attributes that have been made full
The return on investment it is the opposite – TorqSense is used to calculate the use of are its enormous overload capacity, which enables
calculations will include time drag being exerted on the paddle and shaft by the liquid it to cope with robust and demanding test cycles, and its
savings (both in mixing and in being mixed. digital output. The output is fed straight into a computer
process preparation and clean-up), “The mixing process changes the viscosity of the program that compares viscosity measurements with the
and mixed quality including liquid, which is what causes the drag,” says Mark. “In ingredient ratios and calculates changes to the recipes
consistency and bubble-free. the first instance the TorqSenses are looking for the for optimised results. Mark sums up: “This plant is in
Sometimes, the combination of mix viscosity to stabilise to a steady value that won’t change effect a totally automated laboratory that can develop
ratios, viscosities, liquids, pastes and any further no matter how much more mixing is done. perfect formulations in a closed loop calculation. It has
solids cannot be mixed successfully “Then they measure that very accurately. The changed pre-pilot tests from time-consuming trial
any other way. viscosity is what gives the final commercial product its and error to precision materials science.”
MORE INFORMATION: www.intertronics.co.uk sense of quality: a low viscosity and the product feels MORE INFORMATION: www.sensors.co.uk

Technical innovation for mixing and agitation

ord Drivesystems has developed a powerful compact design enables operation under ultimate external lowers maintenance costs. Not only is the oil level and
combination for use in mixing and agitation loads. For agitation applications, a combination with the thus the required oil volume lower, but thanks to fewer
processes: The MAXXDRIVE industrial gear SAFOMI IEC adapter is recommended, in which an oil attached components the installation space is also
Nunits with the new SAFOMI-IEC adapter is expansion chamber is directly integrated. reduced.
specifically developed for mixers to improve operational SAFOMI is available for MAXXDRIVE parallel gear For the further reduction of wearing parts and attached
reliability and reduce the need for the replacement of units in the sizes 7 to 11 covers maximum output torques components, Nord recommends a combination of
wearing parts. In combination with the NORDAC FLEX SK from 25 to 75kNm. SAFOMI impresses with its compact MAXXDRIVE industrial gear unit, SAFOMI-IEC adapter, a
200E frequency inverter for the power range up to 22kW, and simple design and integrated oil equalization volume, drive motor and NORDAC FLEX SK 200E. The frequency
a flexible unit with low maintenance is offered. which means that there is no need for oil tanks and hoses inverter can be flexibly installed and features a high output
MAXXDRIVE industrial gear units, an integral part of or the shaft sealing ring between the gear unit and the IEC range as well as a wide choice of optional functions and
the Nord portfolio for ten years, offer high output torques cylinder, which is prone to leakage and wear. Using the accessories. It can be directly mounted on the motor
from 15 to 282kNm and ensure smooth operation even SAFOMI-IEC adapter instead of the standard IEC adapter without control cabinet.
under demanding conditions. The FEM-optimised and on the agitator drive increases operational reliability and MORE INFORMATION: www.nord.com

July 2021 • INDUSTRIAL TECHNOLOGY 19