The FT4 Powder Rheometer was developed to measure the flowability and processability aspects of powders. The main benefits were seen as the characterisation and classification of both the materials and the processing machinery so that the consistency and efficiency of powder processing could be improved. The background to this is described in Benefits and Opportunities and The Nature of Powders.
The FT4 operating principle and the methodology used, were developed as a new way of evaluating powder flow performance. The approach differs from all existing techniques because it sets out to establish a reproducible dynamic flow condition that more closely resembles the way that powders move during handling and processing. These reproducible flow conditions are used to evaluate how different powder samples compare in relation to factors such as moisture content, level of aeration, particle size range, or merely different batches of the same material.
In terms of a detailed specification, the key benefits are:
- Powder conditioning that allows tests to be repeated and compared (Conditioning of Powders)
- Automated testing and analysis - independent of the operator
- Quick and straightforward operation- tests completed in minutes
- Small volume of sample - down to 10ml
- Repeatability between instruments is high
- Ability to investigate flowability and robustness in relation to any of the key variables
- Dynamic flow modes to simulate gentle to aggressive flow patterns and flow rates
- High sensitivity to detect small rheological changes
- Capable of measuring the rheology of powders and complex semi-solids
- Able to measure the shear strength or cohesion of powders
Apart from the placement of the powder sample into the test vessel, the entire test procedure is automatic and independent of the operator. The system provides the following:
- prevention of unauthorised users
- library of testing programmes
- safety screen to prevent access during operation
- completely automated testing
- completion of the test programme in 1 to 10minutes depending on programme type
- secure binary files of all test data
- automated data analysis to derive the key flowability indices
The FT4 software includes a Data Analysis package that enables the measured test data to be quickly interpreted and summarised.
Data Analysis is a standalone application that can be installed on any computer, allowing analysis away from the laboratory, as and when required.
The Data Analysis package delivers:
- Graphical display of any combination of force, torque, air velocity or air pressure data captured by the FT4 during testing, as a function of time, height or test number
- Graphical display of all values derived or calculated from the raw data. These include:
- energy /test traverse
- energy /min, energy/sec
- torque energy
- force energy
- bulk density
- bulk stiffness
- shear data (see below)
- Rapid interpretation of test results. Data are displayed in a graphical format and can be printed directly or imported into other programmes
- Calculation of key indices such as stability index (SI), basic flowability energy (BFE) and flow rate index (FRI), in a matter of seconds using 'Automated Analysis'
- Rapid analysis of multiple files through the creation of macros. Selection of the appropriate macro and test files allows the application of predefined criteria to all files being analysed
- Independent analysis of raw data test files - generated in binary form (.prb) for efficiency and security - in packages such as Excel