In the tablet manufacturing process, efficiency and speed are key elements to production. The ability to manufacture high quality tablets rapidly depends largely on the quality and integrity of the tooling that is used in production - namely the integrity of the surfaces of tableting punches. The slightest imperfections in tableting punch cup surfaces can lead to production problems including sticking and picking.
What Causes Sticking and Picking?
Mechanical interlocking of formulation powders and slight surface imperfections in punch cup surfaces is responsible for the majority of sticking and picking that occurs in pharmaceutical tableting operations. Having a punch cup surface finish that is free of microscopic defects and resistant to degradation during operation will reduce this impact. For those sticking problems that are physiochemical in nature, precision coatings can also help block the chemical attraction forces that develop between the metallic punch cup surface and many active and excipient compounds.
How Does Sticking Impact Tablet Manufacturing and Production?
Roughened surfaces act to trap powders during compression. As sequential tablets are compressed, the cup face surfaces begin to film. As the film builds, the resultant sticking eventually becomes such an issue that production must be stopped to remove, clean, and polish the punch cup surfaces.
Can Tablet Manufacturers Eliminate Sticking?
Performance and precision coatings can be applied to tableting tooling to help reduce wear and corrosion on the cup faces of tableting punches, delaying or eliminating the onset of surface roughening during tablet production. However, the original surface smoothness of punch cup surfaces is also critical to the tablet manufacturing process. Certain coatings and coating processes can have a significant negative impact on the original surface finish. Therefore, it is important that manufacturers select a coating material and coating process that does not degrade the original finish of your cup face surface.
Conventional coating processes such as electroplating (chrome and nickel), and physical vapor deposition (PVD) inherently generate coatings with microscopic level rough surfaces. Cracks, pits and voids will form in coatings deposited by these processes. While small (some as small as a few microns), these surface defects can trap powders and lead to tablet sticking.
Other precision coating processes, such as the Ion Beam Enhanced Deposition (IBED) process, are able to precisely replicate the original surface finish of tableting tooling - while preserving the original surface finish and critical punch dimensions - and provide microscopic surface smoothness at a level that is unrivaled by conventional coating methods.
The IBED coating process can be used to apply a number of different precision coatings, producing results that are as smooth as the original punch face of tableting tooling. These coatings contain no surface defects, enabling tablet manufacturers to virtually eliminate mechanical powder entrapment and reducing physiochemical adhesion as a source of sticking problems, improving productivity and - most importantly - saving costs.
Dr. Deutchman is currently Chairman and Director of Research and Development at Beamalloy Technologies, LLC where he is directly involved with the research, development, and application of the Beamalloy patented IBED coating process. He is the author of numerous articles published in a variety of scientific and trade journals, holds numerous patents, and lectures widely on surface engineering.
