Weight Variation of Compressed Tablets. III

Fluidity of Granules. (Coefficient of Friction of Granules)

Abstract

In order to study the relationship between the fluidity of granules and weight deviation of tablets during tabletting, granules were coated with vaseline to obtain granules of different fluidity. Actual tests with such granules indicated that the fluidity of granules which affects weight deviation is chiefly static friction (Fig. 1), since greater its coefficient, the greater becomes the weight deviation (Fig. 3). The coefficient of static friction increases with the increasing amount of powder (incluing lubricant powder) in the granules (Fig. 4). From these results, it seems more advantageous to have the granules as small as possible and its limit seems to be 100 mesh (Fig. 5). The lubricant powder effects decrease of the coefficient of static friction of sticky granules but such ability differs with different grades (Fig. 6). It seems, from these results, that it would be significant to measure the static friction coefficient of granules in checking the granular quality of a lot in the plant.