STFI Formation uses beta radiography to give you a complete formation spectrum for the evaluation of local grammage distribution.
Formation is important for the wet pressing and drying in the papermaking process, as well as for the end use properties of the paper. The beta radiation method is directly dependent on the mass of the material in contrast to optical formation which also depends on the light-absorption and light-scattering properties of the material.
The analysis gives you information about the occurrence of flocs of different sizes and it is also easy to discern periodic disturbances, e.g. wire marks, as these appear as "peaks" in the spectrum.
Beta formation is applicable to sheets with a maximum average grammage of about 90 g/m2. The maximum analysed area is 145 x 86 mm.
The formation analysis includes a one dimensional FFT and the results are presented with spectrum and formation numbers.
- A formation spectrum can roughly be said to show the total grammage variance of the paper divided into independent wavelength components from 0.25 to 32 mm, see figures below.
- The normalized formation numbers in wavelength intervals for small scale formation F(0.3 – 3 mm), large scale formation F(3 – 30 mm) and the combined range F(0.3 – 30 mm).
Additional features available:
- Oriented formation. Are the variations higher in a specific direction?
- The analysed area saved as actual grammage values (transformed from greyscale) in Matlab-format (or ASCII-format).
We carry out analysis commissions as well as trouble-shooting projects within the field of paper formation.