Capping or lamination is the horizontal separation of a tablet during manufacture. Capping happens when the upper or lower part of a tablet separates as the press ejects the tablet. Lamination is a horizontal separation that occurs at any other part of the tablet. Both capping and lamination are often the result of air entrapment in the formulation. It can be reduced by minimizing elastic deformation, via adjustment of the process or the formulation.
Capping and lamination can be minimized by reducing the elastic deformation relative to the tensile strength.
- Optimise formulation to reduce elastic recovery (e.g. reduce starch content)
- Reduce the amount of fines in the formulation
- Use proper tooling; damaged punches promote capping and worn die cavities can result in slip-stick behavior
- Reduce air entrapment by optimisation of pre-compression
- Reduce air entrapment by using tapered dies
- Reduce the tablet thickness by different shaped tablets
(e.g. change from deep concave punches to flat beveled)
- Decrease compression pressure
- Increase dwell time
- Optimise lubrication