Reaming system with indexable inserts that is both cost-effective and flexible


To produce small batches and prototypes, Riedl Leuenstern GmbH needs a flexible, modular tool system. Duomax reamers with indexable insert technology from KOMET DIHART® match the Herne-based company's production concept perfectly.

Riedl Leuenstern GmbH provides its customers with the entire process chain for manufacturing complex components for general mechanical engineering, including the CE declaration of conformity. The company, directed by Michael Riedl Leuenstern and his brother Stefan, supplies flame-cut parts, waterjet cuts and welded assemblies and takes care of the entire mechanical machining process and even electrical controls. The company's customers range from the coal and steel industry and pipeline manufacturers, construction machinery manufacturers and the automotive industry, through to turbine manufacturers and aeronautical engineering companies.
In order to produce its small batches and prototypes as efficiently as possible, the company uses state-of-the-art technologies – including modular tool concepts for machining. DIHART® Duomax  cutting rings with indexable insert reaming technology from the KOMET GROUP as well as  KOMET  ABS® extensions are the perfect solution here, which is clear to see from the internal machining of cylinder liners.
Due to the small batch size of 40 parts, the 410-millimetre-deep hole in the cylinder liners should be precision bored following two-sided pre-drilling to create a high-quality finish. But this takes a long time and is an expensive process. As an alternative, the company first considered purchasing a reamer specially tailored to this type of machining with soldered cutting edges. But this would have made the tool too expensive. The indexable insert technology of the DIHART® Duomax cutting rings represented a more economical solution, which is more cost-effective in terms of both procurement and machining. This is because the indexable inserts have two fully usable cutting edges, thereby doubling their tool life. And the KOMET GROUP is able to carry out retipping with screw-fit indexable inserts in a matter of minutes – much faster than the use of soldered cutting rings. The basic bodies of the cutting rings also have a longer tool life, as they are not subjected to thermal stress as a result of soldering.
In addition to improved stability and precision of the basic bodies, the new DIHART® Duomax cutting rings offer further advantages thanks to the indexable inserts ground into the insert seats. For example, the process of finish machining each cylinder liner, which previously took around 30 minutes with precision boring, has now been reduced to less than five minutes. Process reliability has also increased thanks to the DIHART® Duomax cutting rings. While there is a possibility of an insert breaking or the hole becoming tapered during precision boring,  Riedl Leuenstern GmbH is now able to produce a high-quality surface finish and absolute dimensional accuracy with reaming.
The modular design of the entire tool concept has benefited the company far beyond the machining of cylinder liners, as the tools and their components can also be used for other parts. The cutting ring holder with the DIHART® Duomax cutting ring is mounted on two KOMET ABS® extensions (190 and 85 millimetres) from the KOMET ABS® range in order to achieve the total required projection length for the 410-millimetre-deep hole. The KOMET ABS® coupling system for rotating and stationary tools is based on the principle of modularity. This means that users can quickly and cost-effectively use modular machining tools, extensions and adapters. Finally, the entire assembly is mounted on a DIHART DAH® compensating holder. This guarantees optimum tool concentricity, as the concentricity of the cutting edges can be adjusted with µm accuracy, thereby eliminating the possibility of machine spindle errors.

Riedl Leuenstern GmbH
Roonstr. 5a
44629 Herne, Germany
Phone: +49 (0) 2323 50446
Fax.:   +49 (0) 2323 51624

Information and a video about DIHART® Duomax  can be found at
Information and a video about the KOMET ABS®  coupling system can be found at

Press contact

Trade press:

Wolfgang Klingauf

+49 (0) 821.524693