The term “capping” in tablet manufacturing refers to a tablet failure break across the horizontal plane and occurs immediately after compression during the breaking force or friability test.
Capping is a common defect that should be identified in the development stage, but it’s common to realise the problem during manufacturing. There are many factors that can contribute to the cause of capping, such as powder blend characteristics, material deformation properties, and the mechanical configuration of the tablet press and tooling.
Capping issues should be addressed at the development stage. The study of powder permeability can give the formulation scientist early insight to a capping issue.
Powder permeability is a fundamental property affecting the tableting process. Entrapped air in the powder blend reduces the inter-particulate bonding as well as the final tablet tensile strength, which leads to tablet failures, such as capping. High permeability indicates less air entrapment during the tableting process and fewer tablet defects. These experiments can be conducted on a lab scale Powder Rheometer, such as the FT4 from Freeman Technology.
Click here to read 'Resolving Capping Issues in Tablet Manufacture' from Natoli Engineering.