A Mechanistic Approach To Model the Compression Cycle of Different Toolings Based on Compression Roller Interactions

The aim of the current work was to model and understand the mechanical interactions of tooling heads with compression rollers during tableting. Binary direct compression blends of Prosolv® SMCC with 0.5% w/w magnesium stearate and ternary blends with 30% w/w acetaminophen were used. Tablet compression was performed using an instrumented Riva Piccola press with 10 mm round flat face D- and B-type TSM domed punches. Five punches were used for the study with varying dimensions of head flats. Strain rate studies were carried out at 12.5, 25, 50, and 75 revolutions of turret per minute (RPM) and a compaction profile was performed at compression pressures of 50, 100, 150, and 200 MPa. Tablet weight, thickness, and tensile strength were evaluated. Compression raw data was used to model the punch interactions. A MATLAB program was created to model the head profiles based on their dimensions, punch tip separation, vertical velocity, and pitch circle diameter of the press. Tablets compressed with no head flats were the weakest and showed less strain rate sensitivity. Tensile strengths increased linearly with the head flat dimensions. Also, difference in loading times due to roll movement during compression was evaluated. Capping was observed in tablets compressed at 75 RPM from the ternary blend containing 30% acetaminophen. However, punches with zero head flat showed no capping at these speeds. Also, B-type tooling showed relatively less capping tendency. This work shows that dwell time effect on tablet properties is based on the punch head flat region and the punch head interactions with the rollers.