Optimizing surfaces in a single step
Viktor Glushych, group manager Coating LMD and Heat Treatment at Fraunhofer ILT, is pursuing a new groundbreaking approach for extreme high-speed laser cladding (EHLA). The process coats quickly and conserves resources, but in most cases, surfaces need to be post-machined. Simultaneous coating and roller burnishing (SCaRB) combines EHLA with roller burnishing in a single process step. While the applied layer is still warm, a roller tool runs over the resulting surface, plastically compacting it and smoothing out roughness peaks. This creates a dense, pressure-saturated surface layer with high surface quality and without needing ablation or any additional setup.
"This saves time, tools, and material," says Glushych, explaining the advantages. "At the same time, SCaRB can specifically influence the microstructure and internal stresses. This improves the wear and corrosion resistance and increases the fatigue strength of coated components." At Formnext, Fraunhofer ILT will be presenting an EHLA rolling demonstrator that allows visitors to comprehend how the combined process control works live.
PFAS-free multi-material coatings
In addition to pure metal layers, multi-layer coatings made of different materials can also be applied. Here, the EHLA process for metal layers is combined with the application of a PEEK layer to produce functional composite layers. PEEK is a fluorine-free high-performance polymer and an attractive alternative to PFAS coatings. "The innovation lies in using the residual heat from the EHLA process to melt a deposited PEEK layer in the immediately following step. A nozzle technology developed at Fraunhofer ILT is used for this purpose, which enables homogeneous application. This hybrid coating system combines the properties of two individually adjustable functional layers," explains Rebar Hama-Saleh Abdullah, research associate at Fraunhofer ILT.
The metallic EHLA layer can be used as a corrosion protection layer (e.g., for pistons), as an emergency running layer (e.g., in wind turbines), or as a thermally conductive intermediate layer. Depending on the additives used, the PEEK layer applied on top serves as a non-stick layer, a sliding layer, or additional corrosion protection. “The adhesive strength between metal and polymer is achieved by clamping the plastic to the rough surface specifically created using the EHLA process,” explains Dr. Christian Vedder, Head of the Surface Technology and Ablation Department at Fraunhofer ILT.
Printed sensors, smart components
Additive manufacturing creates components layer by layer, thereby making areas accessible that cannot be reached from the outside. The approach of incorporating sensors directly into metal parts builds on this, such as printed strain gauges in LPBF components. The sensor layers are created using inkjet, aerosol jet, or pad printing; the sensors can be applied during or after assembly and positioned with precision. The smart components manufactured in this way provide real-time data on load, deformation, or incipient crack formation, for example.
"These sensors are located exactly where data is most useful, even in areas that would be inaccessible with conventional manufacturing," summarizes Dr. Samuel Moritz Fink, group manager Thin Film Processing at Fraunhofer ILT. "This enables us to monitor conditions during operation, do predictive maintenance, and provide greater operational reliability. At the same time, system complexity is reduced because separate superstructures, cables, or external measuring points are no longer necessary. Target industries range from aerospace and energy to mechanical engineering."
Fraunhofer Institute for Laser Technology ILT
