Potentials and limitations of thermography as an in-line tool for determining ribbon solid fraction

Abstract

The solid fraction of ribbons is one of the key quality attributes during roll compaction/dry granulation, as it predominantly determines the solid fraction and the size distribution of granules. Thus, the development of an in-line measuring technique for monitoring the solid fraction of ribbons during production is highly desirable. Infrared thermography was recently described to be a potential approach, but was so far only tested for MCC. In this study, the applicability of this technique was tested for a number of fillers with different physical characteristics and mixtures with glidants and lubricants. For each material, ribbons were produced and the in-line determined ribbon temperature correlated with the off-line determined ribbon solid fraction. This data was used as a calibration to predict the solid fraction in subsequent studies with varying process parameters. The results show that the technique is applicable for a range of materials, but limited for materials that tend to excessive sticking on the rolls. When magnesium stearate was used, the temperature was increased drastically. This phenomenon could be attributed to additional heat development within the tamping unit. It is concluded that this technique has promising potentials for a range of materials.