Fraunhofer develops Laser Direct Plating to better protect metal moving parts

“Laser direct plating” creates functional layer directly on base component.

Researchers at Fraunhofer IWS (IWS) have developed a new laser-based technology called Laser Direct Plating that produces metallic layers faster, more energy-efficiently and at lower cost than established processes.
The process helically wraps strip-shaped metal around rotationally symmetric components and locally creates a metallurgical bond to the substrate using laser energy. The base material remains solid, the surface stays smooth and requires little to no post-processing. Users significantly reduce cycle times, energy consumption and process costs.

Laser Direct Plating combines minimal heat input with a defined forming force. At the joining interface, oxide layers rupture, fresh metal surfaces react immediately and form a durable metallic bond. Unlike laser metal deposition, the coating does not melt over a large area but remains largely in the solid phase. This mechanism lowers energy demand, increases deposition rates and stabilizes layer quality along the entire component length.

“We aim to minimize or even avoid the molten phase,” said Marko Seifert, Head of the Heat Treatment and Thermal Coating Department at IWS. “We activate the contact zone with very little energy and achieve dense, uniform coatings in significantly shorter process times.”

Functional principle and differentiation

Direct plating targets rotationally symmetric components. The strip feeds at constant speed, wraps helically around the substrate and bonds to it during winding. Laser radiation heats the contact zone only briefly to joining temperature. The combined effect of heat and pressure creates a metallurgical bond. This distinguishes the process from laser metal deposition with continuous melting of the coating material. Laser Direct Plating generates the functional layer directly on the component.

Strip speeds in the meters-per-minute range enable high deposition rates, reaching what ILT calls “the three-digit kilogram-per-hour corridor”. Limited thermal impact confines the heat-affected zone to the immediate joining line and preserves the substrate microstructure. The surface exhibits a homogeneous, rolled-like texture; turning, grinding and polishing require far less effort. In an industrial reference, coating time for a hydraulic cylinder dropped from around 20 hours to about six hours. Depending on the setup, energy demand falls by up to 90 percent.
Design and materials

Helical deposition creates defined butt joints sealed by a trailing joining step. For corrosion-critical applications, a multilayer design proves advantageous because from the second layer onward, similar materials bond to each other and minimize dilution. Typical layer thicknesses range from about 1 mm to 3 mm. Multilayer stacks reach several centimeters in total thickness. Selective volume build-up along the component length also enables tailored profiling. Different materials across layers create multifunctional coatings.

Laser Direct Plating improves wear- and corrosion-resistant coatings for hydraulic cylinders, process and forming rolls and plain bearings. For refurbishing worn rolls, the process rebuilds missing volume in a targeted manner. This saves material and shortens downtime.

IWS has filed a patent application for Laser Direct Plating and built a pilot system for components up to 2 m in length. The development team qualifies applications, defines process windows and demonstrates economic viability using demonstrators. Scaling proceeds in cooperation with the system manufacturer and industrial partners. The goal is a robust design for series production with clearly defined cycle time and quality metrics.