The place we always start when solving defects is weight. Always minimize weigh fluctuations. Any variation in weight can and will affect capping.

Slow the press down just to see if the capping will improve. If it does this means that the slower speed provides ample dwell and air release time. This means we can make adjustments to punch penetration, and pre-compression which should allow us to increase the press speed. If slowing the speed down did not improve the capping, then the powders may need to be looked at; it probably isn’t the press. I understand that no one wants to say it’s the powder because they think formulation changes may lead to regulatory issues, and it is possible, but not always true.

Compression force: some granulations need a lot of dwell time and small change can mean the difference between success and failure. A robust formula is what is needed to perform at high speeds otherwise they are very temperamental, meaning any slight change in particle size, and moisture content could mean failure. Start by making a soft tablet with low force, and then make small adjustments to increase hardness. This assures that over-pressing is not the issue.

Michael Tousey
Technical Director/CEO
For more information on capping, visit the Techceuticals blog here