Time for a World Tooling Standard

March 2, 2008
Pharmaceutical Technology

Volume 32, Issue 3

After two centuries, there's no reason to maintain two tablet compression tooling standards.

If your business is in the tablet compression industry, then you are most likely using tablet compression tooling of the standard "B" and or "D" configuration, regardless of the country you are in. Tablet compression tooling is often referred to as tooling, or more commonly, punches and dies. Tools to compress bulk materials into a solid form to preserve, store, transport, and distribute materials have been used for hundreds of years. But in the late 1800s, Frank J. Stokes designed, engineered, and commercially produced the rotary tablet press using the same basic "B" and "D" type tool configuration that we know today. This configuration is the most common and is recognized internationally. Unfortunately, there are two types of B and D tooling; the American standard known as the TSM standard and the European standard known as the EU, or "Euronorm" standard. These two configurations are so similar that only a trained eye can distinguish them. Yet they are different enough that the two configurations cannot be interchanged.

Dale Natoli

To better understand the differences between the American and European tool configurations, it is helpful to know a little about tooling history. In the early 1900s, Stokes commercially mass produced the rotary tablet press using the common B and D type tool configuration. The Stokes tablet press was so successful that Stokes distributed tablet presses to practically every industrialized nation, soon making the Stokes tablet press the most common press in the world. Stokes contracted with the English company Thompson and Capper to manufacture the Stokes tablet press and tooling, which gave Stokes a more strategic European position. At some point, due to economical and political pressure, Stokes was forced to abandon its alliance with Thompson and Capper and concentrated manufacturing at its main facility in Philadelphia, Pennsylvania.

Transatlantic competition

After Stokes cut ties with England, the trained English engineers and staff decided to compete with Stokes—then the world's leading manufacturer of tablet presses—by producing their own. The English facility took its name from the industrial complex in which it was housed, and so was christened "Manesty Machines Ltd." Manesty knew that it was going to be a difficult task to compete with Stokes. In order to compete, the Manesty staff reengineered the B and D tool design, enhancing it to better cope with the stresses and shocks common to tablet compression. While the new Manesty tool design looked very similar to the Stokes design, it was engineered to be unique only to the Manesty tablet press design and was incompatible with the more common Stokes machines.

It didn't take long for Manesty and their aggressive strategy to take the European market from Stokes. In the meantime, Stokes concentrated its efforts on maintaining the United States territory, growing its business by selling into the rapidly expanding pharmaceutical industry. Soon Stokes and Manesty became the major worldwide suppliers of tableting equipment and were divided not only geographically, but also by tool design.

With the acceptance of shaped tablets and the growing tablet compression industry in the late 1950s, the Stokes manufacturing facility became overwhelmed with new business and found it difficult to supply and maintain the demand for tooling. This resulted in lead times of more than six months. The growing pharmaceutical industry could not tolerate these extended lead times and requested tool drawings from Stokes to source tooling from local machine shops. Their request was met with resistance.

The industry decided to establish a committee of pharmaceutical manufacturers who reverse-engineered tablet tooling drawings and made the drawings available to the pharmaceutical industry. Major pharmaceutical companies, such as Upjohn, Smith Kline French, and Winthrop collaborated with the American Pharmaceutical Association to publish and distribute the Industrial Pharmaceutical Technology (IPT) Standards Manual, the first ever edition of tool standards. At the time of publishing, IPT was a working section of the American Pharmaceutical Association. IPT was consequentially dissolved and the manual renamed TSM, for "Tableting Specification Manual," currently published in the seventh edition.

Tool drawings were also required to perform critical functions related to tablet quality and tablet press operation, including tool inspection procedures and setting limits and controls for punch and die maintenance. The tool drawings also enabled operators to troubleshoot compression and machine problems, such as poor tablet friability, punch binding, and premature tool wear. But most important, the long-term motive of the committee was to publish a tooling standard that governs and softly mandates tablet press and tooling manufacturers to produce equipment in compliance with the American standard. Establishing tooling standards helped to protect the millions of dollars invested in current tooling inventory while maintaining the integrity of established processes and procedures for tool inspection and maintenance. The standards also provided the pharmaceutical industry a uniform price structure useful for budgeting.

Unlike the American TSM standards, the "Euronorm" European standard tool configuration is not published or governed by an organization or association. However, the European tool configuration has been refined and slightly modified from the original Manesty design by European tablet press manufacturers to meet the demand of modern high speed and automated tablet presses.

So today we have two configurations of the world's most common B and D tooling designs; the TSM and the Euronorm. In the past two decades, Europe has dominated the tablet press industry. Therefore, all tablet presses manufactured in Europe for use in the United States must be modified from European design to meet the requirements of the TSM tool configuration. Unfortunately for American tablet manufactures, the Euronorm tool configuration is superior in design and function over the American TSM type. To obtain the peak performance of high-speed tablet presses, serious consideration should be given to modify the original TSM tool configuration to better match that of the Euronorm configuration for which the modern presses have been engineered.

Where do we go from here?

Modifications to the TSM tool configuration are called tooling options and listed in the current TSM Manual. The US is the only country in the world using the original Stokes design, so products being transferred to or from the US may react differently to compression settings and may not be consistent with the original manufacturing site. The two tool configurations are so close to each other that it may be time to consider a world tooling standard. Such a standard would allow consistent tooling and press performance regardless of manufacturing location and interchangeability of tooling between countries. It also would provide a benefit to the tablet press manufacturer who would then be able to produce presses using only one common tool configuration.

Here is a list of the differences between the TSM and Euronorm tool configurations:

  • The TSM punch head configuration has an angled top profile compared with the Euronorm configuration, which uses a domed type head profile. The domed head profile accepts the pressure of the compression roller for tablet compression and reduces the shock and bounce that commonly occurs with the TSM angled profile. Tablet press cams designed for TSM tooling can use the optional domed head design without further modifications to the tablet press or cams and should be considered a standard for all high speed presses.

  • The TSM punch inside head angle for B type punches is 37° compared with the Euronorm, which is 30°. The difference between the head angles provides no benefit for either configuration. The inside head angle for the D type configuration however is the same 30° angle for both the TSM and Euronorm type.

  • The overall head thickness is greater in both the B and D configurations for the TSM than for the Euronorm type. Manesty's original theory was that reducing the head thickness would reduce the weight. A lighter punch requires less energy to move vertically through the various compression cycles.

  • The overall punch length of the TSM tool is 0.010 inches shorter than the Euronorm and provides no benefit to either configuration.

The major difference between the two competing tool configurations is the angled head profile of TSM versus the domed head profile of the Euronorm, with the domed head profile being the configuration of choice by the modern, high speed tablet press manufacturers. I see no advantage in maintaining two tooling standards for reasons that cannot truly be justified. Establishing a single punch configuration only makes good sense and will provide overall consistency and efficiency to the pharmaceutical industry.

Dale Natoli is vice-president of Natoli Engineering, dale@natoli.com