Contrary to the appearances, the tablet compression process is a very sophisticated, complicated and demanding process, just to mention substantial static and dynamic forces run on punches and dies. Compression tooling turns out to be then one of the most important and delicate elements of this process because its quality decides about produced tablets weight, hardness and appearance.  Certainly, equally important are the conditions and the practice of using the tooling in the correct way.

Performance of the compression tooling during the tablet compaction process depends on its right design which results in its ability to overcome the numerous process problems as capping, picking and sticking, to name only the most common, but also to ensure the maximum tooling lifetime. Most of these problems could be avoided or at least limited already on the stage of the tablet design but for the most of the applications we need to cope with existing tablets and established formulations. In such a case, no substantial modifications of tablet design are permissible. The changes involve mainly embossing parameters as stroke angle, width and depths or slight corrections of the concave radiuses.

From this point of view, the only available way to influence the process and solve the problems remains tooling design including the right choice of the construction material and enhancing the tooling performance by the correct heat treatment, applying coatings or special modifications as rotating heads etc.

Tailoring tooling to the application is then one of the most important factors to make the compression process as much effective as possible. Therefore, the clear and precise requirements specification by the process owner is a crucial success factor.

Essential information needed for the correct tooling design could be divided in five main groups:

1. Information about the tablet – usually tablet drawing or samples;

2. Information about the tablet press – machine producer, machine model, number of stations and tooling standard (TSM or Euronorm);

3. Information about the tooling – tooling configuration (B or D with specification of the die size in case of B tooling – B, BB, BBB or BBS), material of construction and coating (if should be follow by the tooling supplier), specific requirements for surface roughness, dimensional tolerances and tip/die bore clearance (if vary from common standard values), key angle (in case of shape or multitip tooling), dust groove standard (if needed), tooling marking (if different from tooling supplier standard), any other specific tooling modifications and the requested number of tooling including spares;

4. Information about the compressed product – product properties (sticky, abrasive, corrosive), compression problems if occurred in the past (capping, picking, black spots etc.), compression force needed (if it is known from previous experience);

5. General information – any specific documentation needed (if vary from standard measuring reports, material and coating certificates, delivery documentation).

Most of the compression tooling suppliers are assisting their customers with RFQ forms which assures the gathering of complete information needed for a fast and smooth and cost-effective quotation, ordering, producing and tooling delivery process.

Artur Jakubiak
Development Director at Adamus S.A.