Sticking and picking are ubiquitous problems in tablet manufacturing and generally arise from either formulation or tablet design inadequacies. Sticking occurs when formulation granules stick to the face of the punch cup. Formulation sticking in the letters and characters of punch embossing is typically referred to as picking. Both result in tablet defects and lower production due to time spent troubleshooting.
Solutions to sticking and picking include changing the formulation, increasing compression force, and reworking the punch design. An alternative option is to have a coating applied to the punch, which will facilitate or enhance product release from the punch cup. A number of coatings are available, and deciding which to use depends on the unique characteristics of the formulation to be compressed.
Natoli offers a variety of coating types and process technologies to improve the surface characteristics of tooling and tooling performance. Continuous improvement efforts have driven Natoli to evaluate relevant coating parameters for the different coating types and process technologies such as coating thickness, hardness, adhesion, coefficient of friction, surface roughness, hydrophobicity, wear rate, and corrosion potential. Understanding how these parameters effect product release, wear resistance, and corrosion protection is of vital importance when selecting the appropriate coating for an application.
In our new infographic “Which Coating Solves Your Tableting Issues?”, we rank specialty punch coatings per our coating evaluations on how well they protect against corrosion, resist wear, and enhance product release. Nickel fluoropolymer, a coating in which nickel with a fluoropolymer is deposited by electroless electroplating on the punch, best enhances product release and reduces sticking and picking. However, nickel fluoropolymer is not ideal for all formulations; it can only be used with extremely soft formulations. Generally, chromium nitride or Natoli Ultracoat is the best coating for enhanced product release. Natoli Engineering currently offers hard chrome, Natoli Ultracoat, chromium nitride, titanium nitride, diamond-like carbon, nickel fluoropolymer, Teflon inserts, and boron carbide coatings.
Discuss these issues with your tooling vendor early in the process to help reduce production issues and additional costs and increase the quality of your tablets. Your tooling vendor should be able to explain the unique properties and advantages of the various steels and coatings available for your tooling.
For more information about how Natoli’s coatings can help solve your tableting issues, contact us today!