Fette Compacting America

FROM THE WORLD OF GLOBAL CUSTOMER SUPPORT (PART 2): SEARCHING FOR CLUES

High-quality spare parts safeguard efficiency and process reliability over the entire life cycle of a plant. Fette Compacting exclusively supplies uses OEM (Original Equipment Manufacturer) products for international support with spare parts. The qualitative differences which can arise between original and generic parts are shown by two scientific studies using compression rollers as an example.

Rolling at a pressure of up to 160 kN over the punch heads, compression rollers are typical wear parts in a tablet press and are available from various suppliers in the spare parts market. The great differences in quality between suppliers often only become apparent during stress tests and analyses under a scanning electron microscope.

Metallurgical comparison of compression rollers

In order to compare the material quality of compression rollers in detail, Fette Compacting commissioned two American test laboratories - Dayton T. Brown and Taber Industries - with the performance of metallurgical analyses, whereby the scientists compared a nitrated compression roller from Fette Compacting with the generic product of an American after-market manufacturer.

The test results are conclusive: the compression roller offered by Fette Compacting displays a significantly higher material quality in all areas while a stress test indicated the devastating consequences of inferior quality: the surface of the compression roller wears faster and gives off low volumes of abraded metal onto the punch heads. The metal is then transferred onto the next compression roller which triggers a vicious cycle. Subsequently, the tableting tools are also damaged and need to be replaced sooner.

Carbon and chrome - less is more

The analysis displayed major differences in material quality.

One key indicator of steel quality is, for example, the percentage of carbon.  The greater the percentage of carbon, theoretically, the stronger the steel; however, with as little as 0.8 percent carbon content, the steel reaches a tipping point where the strength supersedes ductility and this in turn can impair the overall strength and durability of the component and even lead to premature fractures.  In the case of the compression rollers supplied by the competition, this value is significantly higher than this 0.8 percent limit.  In the case of the compression roller offered by Fette Compacting, the measured values remained below the saturation limit.

Another factor leading to higher wear and swifter failure of the component is chrome content. Increased chrome content causes the metal structure to become more brittle, which diminishes strength. Compared to the generic product, the Fette Compacting compression roller displayed less than half the chrome content. This quality advantage is made possible because Fette Compacting exclusively uses heat-treated high-end tool steel while the competitor relies on inexpensive steel alloys.

Two compression rollers in a tablet press 3090i from Fette Compacting

A sample compression roller from Fette Compacting (left) and one offered by an after-market manufacturer (right). Sections were removed from the rollers for an abrasion test.

An image under the scanning electron microscope shows how the generic product sample (right) displays greater inclusions of undissolved carbides which have a negative impact on the strength and durability of the component.

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