Founded in 1888, Ruhstrat GmbH has a long tradition in high temperature furnaces. At the end of the 19th century, co-operation with Noble prize winner Prof Walter Nernst from the University of Göttingen resulted in the construction of the first resistance heated high-temperature furnace suitable for temperatures up to 3000°C. Since then, Ruhstrat has focused on customised solutions for advanced heat treatment of powdered materials and graphites. In the 1990s specialist MIM equipment for debinding and high temperature sintering was introduced, including a continuous sintering furnace operating at around 1500°C.
In addition to serving the PM industry, Ruhstrat has been building continuous furnaces for the carbon fibre producing industry, where temperatures up to 3000°C are commonplace. It is this capability which led to a close co-operation between Eisenmann and Ruhstrat. In 2011, following a number of years of cooperation, Eisenmann AG acquired Ruhstrat.
Eisenmann entered the PM industry at the end of the 1990s, when it introduced its first high temperature roller hearth sintering furnace. The Eisenmann system consists of individual furnace modules, each with its own roller drive unit, connected through double gate door systems. This allows the user to set a unique temperature profile and atmosphere, adapted to the specific needs of each processing step in the sinter process (delubing, sintering, hardening, annealing etc). With sintering temperatures up to 1350°C and atmosphere separation, both traditional as well as advanced materials could be produced with a very high accuracy.
With the brand new office and manufacturing facilities in Bovenden, between Kassel and Hannover, just finished and the integration of Ruhstrat in the Eisenmann group now completed, it has been decided that PM activities of both companies will be joined and centralised in Bovenden, in order to exchange know-how and experience.
The first results of this co-operation have already been demonstrated in the joint development of a second generation roller hearth sintering furnaces. Combining Eisenmann’s extensive know-how in roller furnaces and Ruhstrat’s long time experience with protective atmosphere, the next generation sintering furnaces has been commissioned. These new furnaces feature an efficient delubing system with an optional direct gas fired section, combined with improved energy efficiency and lowered gas consumption.
The group has furnace manufacturing capabilities in Germany, US, Mexico and China.