In This Issue -
February 2016 Newsletter
To celebrate the launch of a new instrument from Freeman Technology, we are dedicating this newsletter to our new Uniaxial Powder Tester (UPT). It is not just a new tester but a new commercial testing technique for those handling and processing powders. The UPT draws on our engineering expertise and unique experience of modern requirements for powder testing, and I’d like to thank everyone who has supported its development, from our collaborators at the University of Edinburgh to each member of the Freeman team. This newsletter provides some insight into the team involved, the new instrument, how it works, and how it will bring value to those working with powders.
The UPT meets industrial requirements for a powder tester that combines the speed and cost-efficiency of simpler equipment with the accuracy and relevance of more sophisticated instruments. So many powder processes remain sub-optimal for want of the insight that effective powder testing can deliver. Our hope for the UPT is that it will help engineers to achieve greater manufacturing efficiency by making powder testing more accessible and routine.
A primary point to understand about uniaxial testing is that it measures Unconfined Yield Strength (UYS) - a parameter that is already widely used to quantify and compare powder flow properties. UYS (σc) is usually derived indirectly by applying a mathematical model to yield locus data measured during biaxial shear cell testing. Uniaxial testing is a far simpler approach that measures UYS directly. This means:
And upfront equipment costs are far lower than for a typical biaxial shear cell tester.
A summary of shear cell, uniaxial and simple powder testing techniques
1. Techniques such as flow through an orifice, tapped density, angle of repose
2. Under consolidated conditions
“The simplicity of uniaxial testing has always held considerable industrial promise, but the practical implementation of the technique is not without its challenges,” observes Jin Ooi, Professor of Particulate Solid Mechanics, University of Edinburgh. ”The Freeman name is synonymous with powder testing and engineering excellence within that field, so Tim’s decision to commercialise a version of the Edinburgh Powder Tester (EPT) was both exciting and welcome. The result is a major step forward in powder testing - a completely new, easy-to-use instrument that makes it far easier to access the UYS data that so many of us are familiar with. We hope that the industrial community will rapidly recognise the UPT’s potential to make a real difference in powder handling practice.”
Dr Katrina Brockbank, Head of Laboratory - “In the lab we’re used to the samples changing, but not the equipment, so it has been a fascinating process providing feedback into an evolving design. A key focus has been proving robustness and reproducibility. The UPT may have far fewer capabilities than the FT4 but we want users to have that same faith in their data. So, we’ve undertaken lots of repeat testing with different hardware designs and many types of powder. Throughout we’ve been keenly aware that not everyone shares our passion for powder testing, so we’ve been making plenty of suggestions on how to make measurement easier.”
Rob Hopkins, Mechanical Design Engineer - “One of the analogies we use to explain uniaxial testing methodology is to say it’s like building a sandcastle and then measuring the force needed to flatten it! However, the powder column building technique is critical. The double-ended compression mechanism that came from the University of Edinburgh is one of the engineering features that underpins its performance.” To see it in action, go to our YouTube channel.
Ceri Workman, Systems / Software Engineer - “The UPT is all about making powder testing more accessible so we knew that the software interface had to be clean and simple. Software really shapes your experience of using an instrument. We wanted a supportive environment for non-expert users and so we have provided an intuitive, simple interface for control and data reporting.”
Giles Hughes, Production Manager - “One of the ways in which we safeguard the quality that Freeman is renowned for is by building in-house. The UPT is no different from the FT4 Powder Rheometer in this regard, though a simpler system. For us the main challenge has, therefore, been sourcing new components, optimising build sequence and ensuring quality and reliability.”
Image - Left to Right: Rob Hopkins, Dr Katrina Brockbank, Giles Hughes, Ceri Workman
The UPT will have its first major outing at Powtech on stand #4-547, which runs from 19 to 21 April 2016 in Nuremberg, Germany. http://www.powtech.de/en
...and subsequently at International Powder and Bulk on booth #2835 which takes place in Rosemont, USA, 3-5 May 2016.
Come and visit us at any of these events, or contact us, to find out more about the UPT and how it can help you.
Key to understanding how uniaxial testing could complement existing powder testing methods has been to scope the range of materials for which it could be used. Like conventional biaxial shear cell testing, uniaxial testing becomes more difficult with free-flowing powders where UYS values are low. However, extensive back-to-back tests reveal that the data measured by the two techniques is similar and that the UPT can be used for a very wide range of powders, including those with relatively low cohesivity, such as a spray dried lactose, as well as those that are more cohesive, such as limestone.
“We’re anticipating strong demand for the new instrument from customers who have reached the end of their patience with low cost methods that simply don’t deliver,” said Dr Katrina Brockbank, Head of Laboratory, Freeman Technology. “For example, we’re expecting a warm welcome from bulk solids handlers where methods such as angle of repose fail to solve process problems, but shear cell testing is viewed as too expensive and complex.” Emerging markets where the cost base is often too low to support sophisticated powder testing instrumentation are also expected to benefit from the new tester.