Tablet Lubrication

How to tell if lubrication has been optimised for your formulation

Are you encountering sticking and picking problems in production?

Tablet lubrication problems are a major cause of lost production as they result in tablet defects and often entail reducing machine operating speeds. Optimising lubrication can be complex as the lubricant type, amount and blending time must be optimised to give a well lubricated tablet without over-lubrication which reduces tablet hardness. Lubrication is best studied through the tablet ejection and detachment processes. High ejection or detachment values indicate that the formulation is at risk of sticking/picking. Measuring these values on full scale tablet presses is difficult so these measurements are not carried out routinely in production. The Gamlen Powder Compaction Analyzers have been designed to simplify these measurements so that they can be brought into standard use in development and QC. These tests are easy to carry out and quickly highlight lubrication concerns.

Ejection Stress

Ejection force is the force required the push the tablet out of the die. Ejection stress is calculated from ejection force to account for the punch and die geometries (Stress = Force/Area). It is a measure of how well lubricated the formulation is. Poor lubrication results in tablet defects such as picking, sticking and capping.

Ejection stress is automatically calculated on the D- and R-series instruments. The Gamlen Dashboard software generates ejection force profiles with minimal user input. It also highlights data that is indicative of lubrication problems.

Detachment Stress

Also known as take-off force, the detachment force is the force needed to detach the tablet from the base of the die or the lower punch tip. Detachment stress is calculated from detachment force to account for the punch and die geometries (Stress = Force/Area).  Like ejection stress, it is related to lubrication with high detachment stress values indicating that the formulation is poorly lubricated and at risk of tablet defects.

The D-series compaction analysers feature a unique, integrated detachment force measurement system. When combined with the Gamlen Dashboard software, detachment force profiles are generated automatically which identifies tablets at high risk of sticking/picking. When using The R500 compaction analyser detachment force can be measured using a seperate hand-held force meter (supplied separately).