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The Benefits of Tablet Tooling Standardization
Tooling standardization in the tablet-manufacturing industry is a topic that has concerned tableting professionals for decades. I Holland, authors of the 1992 Eurostandard, the most widely adopted tooling standard globally, has been striving for some time to promote a consensus in this area.
Why was a standard needed?
Conception of the Eurostandard began in the 1970s when conversion from Imperial measurements (inches) to metric measurements (millimeters) first began to take effect, creating a recognized need to reduce variables in tooling specifications/standards set by original equipment manufacturers (OEMs).
As European tablet-press manufacturers started to gain ground in the 1980s against UK press manufacturer Manesty's former market domination, German DIN standards began to be applied to tablet tooling. DIN standards were designed for general engineering components, limits, and fits, but the clearances created by this system are not always appropriate for tablet tooling.
The incongruity occurs because the powder compaction process is different compared with typical mechanical processes that benefit from contact lubrication using general engineering components. The DIN system did not address the issues a dedicated tooling standard could have addressed.
In 1990, I Holland invited prominent tablet-press and tooling manufacturers to come together to formulate a dedicated standard. Unfortunately, however, there was little received interest—possibly because of fears of losing competitive advantages. Despite this setback, the first edition of the Eurostandard was developed and published in 1992. By the time the second edition was released in 1996, the Eurostandard had been adopted as the accepted standard for the vast majority of tablet-tooling markets outside North America.
Simultaneously, during the mid1990s, a group of French pharmaceutical companies and tooling manufacturers contacted the International Organization for Standardization (ISO), to investigate the possibility of establishing a European standard for tablet tooling. This exercise culminated in the formation of the internationally acknowledged ISO 18084.2005 (E) for punches and dies.
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:
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.
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.
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.
Clearances and tolerances
Unlike typical mechanical processes, powder compaction inevitably results in granule coming between the lower punch tip and die bore, resulting in resistance. Consideration should be given to the clearance between such surfaces.
The Eurostandard and the TSM standard avoid these issues by adopting customized clearances, which offer advantages over ISO standards, although there are differences between the two. The Eurostandard adopts a tighter clearance range to help improve general operation and product yield.
Although there are other small variations between the standards, such as seal groove configuration, these variations do not prevent interchangeability and are not detrimental to the running of the tablet press. All of these differences are surmountable.
In recognition of the need to eliminate these variables and specifically take into account the sensible and efficient provisions for cross-platform/press compatibility laid out in ISO 18084, the Eurostandard has been updated to make it compatible with the ISO standard.
A single global tooling standard should be highly desirable for the industry; however, even if tablet press manufacturers could be convinced that it is in their commercial interest to adopt it, it will take time for these changes to evolve. Leading tablet-press manufacturers are always seeking to innovate and move the industry forward so tooling standards will always require revision.
In turn, this means that highquality tooling suppliers will always need to retain the ability to solve complex problems and preserve the skill set within their workforce to manufacture tooling that is compatible with any press worldwide.
In conclusion, I believe that calls for the standards laid out in ISO 18084:2005(E) to be adopted globally should be fully endorsed. However, I also believe that the Eurostandard already represents a comprehensive global standard because it is the most widely adopted tabletting tooling standard today and is compatible with ISO.
Steve Deakin is business development director at I Holland, email@example.com