Qualification of burnishing of additively manufactured components for the production of functional surfaces

• Applicant: Professor Dr.-Ing. Dirk Biermann
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 493122246

In the previous DFG project-period titled "Qualification of burnishing of additively manufactured components for the production of functional surfaces", the fundamental suitability of the burnishing process was examined to optimize the surface properties of components produced by Laser Powder Bed Fusion. In the analysis of rotationally symmetrical samples, the process combination of additive manufacturing and subsequent processing by burnishing proved to be highly successful in reducing the high initial roughness while simultaneously increasing the hardness and compressive residual stresses in the component's surface layer. The low-wear burnishing allows for the production of components with minimal allowances, contributing to time and cost savings in the elaborate additive processes. Regarding dimensional accuracy and form deviation, further optimization of the process steps is necessary, as the final contour is achieved entirely without subtractive manufacturing. Additionally, some remaining cavities can be observed on the workpiece’s surface. Therefore, the aim of the research project is, on the one hand, to extend the post-processing process for freeform surfaces with increased precision of the final contour. On the other hand, surface structuring with deliberately introduced cavities will be investigated.The planned experiments will be conducted using the martensitic steel 1.2709, which includes the development of an adapted processing strategy to consider the challenges of the material's deviating flow characteristics. An extensive characterization of the achieved specimens’ properties will be carried out and compared with the promising research results of the initial project. With regard to industrial application, the future project is motivated by its potential applicability to die-casting and forming tools with regions of pointedly controlled material flow. The advantages of the process chain regarding versatile design possibilities and achievable surface properties can be utilized. Furthermore, the multi-scale modeling approaches conducted in the previous project phase generally confirm the experimental observations. To further improve their predictive accuracy, a coupling of simulation scales is planned in the project continuation so that the influences of high deformations within the surface layer can be represented in a comprehensive model. Finite element simulations can be particularly helpful in the intended design of surface pre-conditioning to reduce experimental effort by identifying suitable topographies in preparation for specimen manufacturing.

• DFG Programme: Research Grants