Seeking a global standard
Recent calls to combine legacy tooling standards and bring them in line with the internationally recognized ISO standard have
become much more widespread. In today's global pharmaceutical marketplace, where many solid-dose companies have manufacturing
plants around the world, there are numerous benefits to having only one standard for tablet tooling, including:
- Interchangeability between tablet presses of different manufacture both in plants and across locations worldwide
- Reduced tooling inventories, which can save costs
- Shorter lead times based on tooling-supplier rationalization
- Standardized procedures (e.g., procurement, operation, and maintenance)
- Standardized equipment and processes for validation and inspection
- Uniform quality and grade of tooling across all products and sites
- More international technical exchange for development and problem solving.
Given these benefits, it should come as little surprise that ISO 18084 is coming to be recognized as the right standard for
the tablet-tooling industry. In fact, there is evidence that the ISO standard is being increasingly adopted among global pharmaceutical
companies, for whom the benefits of rationalization are greatest.
In addition to the Eurostandard and ISO 18084, it should be noted that other tooling standards exist. For example, North America
almost exclusively uses the Tablet Specification Manual (TSM) (formerly IPT) standard.
While punch and die configurations are similar across all standards, there are several key differences. Figure 1 demonstates
variations in the profile of the head form, including head radius/angle, dwell flat, head thickness, head length, and under-head
Figure 1: Variations in the profile of the head form.
The ISO/Eurostandard "domed" head incorporates a radius that blends into the "dwell flat," which gives a smoother lead onto
compression rollers, reducing wear on both tooling and the tablet press. This feature also ensures sufficient dwell time for
optimized granule compaction and allows the tablet manufacturer to produce a quality product. Version 7 of the TSM also recommends
that all new punches adopt this domed head shape.
Variations found between the ISO/Eurostandard and TSM underhead cam angles (Figure 1) result in incompatibility of tooling
between European and TSM tablet presses, meaning that interchangeability is restricted and that tooling inventories increase.
Nominal punch length.
The nominal (overall) punch length is a reference length governed by the dimensions of the tablet-press turret (Figure 1 shows
the differences across the standards). This means that a Euro/ISO standard length punch cannot be used in a TSM tablet press
and vice versa. Standardization of overall punch length would ensure compatibility across all tablet presses and reduce the
cost of tooling inventory for tablet manufacturers.
Keying angles/turret rotation.
All shaped and multitipped upper punches need to be fitted with an antiturn key to ensure correct alignment ino the die. The
positioning of this key relative to the tablet shape is important on high-speed presses to optimize ejection and takeoff of
the tablet from the press. As a result of the different turret rotations, this positioning becomes a challenge. Most modern
tablet presses use a turret that rotates in an anticlockwise direction (e.g., IMA, Fette, Korsch and Kilian machines), while
others rotate clockwise (e.g., Cadmach and Manesty machines). In addition, there are wide variations in keying angles between
tablet-press manufacturers (see Figure 2).
Figure 2: Variations in keying angles between tablet press manufacturers.
These variations in angle and rotation cause problems with the correct presentation of the tablets to the takeoff plate and
in ejection, which can cause tablet breakage. To ensure the correct key position of shaped or multipunches, the set of tools
must be specially manufactured to suit the type of machine, which increases costs and potential inventory.
Currently, there is no move to create or agree on a universal position on keying angles/turret rotation. This will need to
be agreed upon and driven by major tablet-press manufacturers.