Use of cement concrete as a homogenous material and as a composite material in the machine tool design

• Applicants: Professor Dr.-Ing. Christian Brecher; Professor Dr.-Ing. Michael Raupach
• Subject Area: Production Systems, Operations Management, Quality Management and Factory Planning
• Term: from 2013 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 236443356

Structural parts for machine tools (e. g. beds, columns and cross-slides) are predominantly made from steel or cast iron. These materials exhibit good to very good strength properties. Due to scarcity of resources during the beginning of the last century, a first attempt was made to substitute steel by (steel-reinforced) concrete. More stringent material requirements during the 1970s led to the development of novel substitution materials. At that time, reaction resin concrete was favored over cement-based concrete. Today, the use of cement concrete is increasingly desired, due to its low cost, good damping qualities and low density. A further development past the classical cement concrete is called ultra-high strength concrete (UHSC). In comparison to steel, UHSC still significantly lacks in tensile strength, which has to be considered during the application-specific design. First attempts with UHSC were already made in the machine tool and production systems manufacturing industry. However, due to missing fundamental research, a widespread acceptance on the market is still non-existent.The overall goal of the research project is the investigation into usage possibilities of cement concrete in machine tools, both as a pure and composite material, to be able to utilize its excellent economical and mechanical properties despite its weaknesses. To this end, connections between the material and the requirement criteria or individual parts and the requirement criteria shall be established, on the basis of which the development of guidelines for the design of high-performance concrete frame components for the machine tool industry could be established.Within the first research phase, initial scientific fundamentals for a purposeful usage of cement concrete in the machine tool industry were created. Aside from deriving requirement criteria, the raw material was investigated, regarding the solid material characteristics and the dynamic fatigue strength. Coupling points and methods including tie rods were analyzed in detail towards their fatigue strength. A well-performing assembly (bed and moving column) made from cement concrete was created and benchmarked against a welded steel construction.Due to the very promising results, a further investigation into the assembly and material technology optimization potentials for an application-oriented design of cement concrete frame components for machine tools is targeted in a second research phase.

• DFG Programme: Research Grants