Imagine the gear connections inside a jet engine — metal parts that slide against each other thousands of times under extreme stress. Over time, they wear down, and that means expensive repairs and grounded planes. This team at RWTH Aachen combined laser treatments and ultra-thin coatings to harden these surfaces and reduce friction, like giving metal parts an armor layer that also makes them slippery. They even added silver-doped "smart coatings" that change color when they wear out, so you know it's time for maintenance before something breaks.
Crowned spline connections in high-performance gearboxes — especially in aviation engines — suffer from friction and wear that leads to costly maintenance, unplanned downtime, and reduced component lifetime. Current surface treatments don't adequately protect these critical shaft-to-gear connections under extreme operating conditions.
The team built full-scale crowned spline prototypes treated with laser hardening, laser micro/nanotexturing, and PVD multi-layered coatings (including silver-doped smart coatings). These were validated on a test bench under dynamic fatigue conditions, and a technical recommendation was produced identifying the most effective treatment combinations from 20 deliverables.
If you are an aerospace MRO provider dealing with frequent spline wear in engine gearboxes — this project developed laser hardening, laser micro/nanotexturing, and PVD coating methods validated on full-scale splines that reduce friction and wear. The methods were tested under dynamic fatigue conditions and summarized in a technical recommendation ready for industrial adoption.
If you are a gearbox manufacturer struggling with premature wear on crowned spline connections — this project tested combinations of laser surface treatments and multi-layered PVD coatings on full-scale spline components. The consortium of 3 German partners produced 20 deliverables including test bench validation results that identify the most effective treatment combinations.
If you are a surface treatment company looking to expand into high-value aerospace and precision mechanical components — this project mapped out which combinations of laser hardening, laser texturing, and reactive magnetron sputtering PVD coatings work best for crowned splines. The statistical test plan and technical recommendation from 20 deliverables give you a validated process roadmap.
The project data does not include specific cost figures. However, the methods use established industrial technologies — laser processing and PVD magnetron sputtering — which are already available commercially. A coating service provider could apply these treatments without building new infrastructure from scratch.
The project validated treatments on full-scale spline components, not just lab samples, and conducted dynamic fatigue testing on a test bench. The laser hardening method is described as 'almost established' industrially, while the laser texturing is newer but was proven at component scale across 20 deliverables.
The project was coordinated by RWTH Aachen under a Clean Sky 2 Joint Undertaking call. IP rights typically follow the EU grant agreement terms, with results owned by the partners who generated them. Contact the coordinator at RWTH Aachen's WZL laboratory to discuss licensing or collaboration.
Full-scale spline prototypes were built and validated on a test bench under dynamic fatigue conditions. The consortium produced a technical recommendation summarizing the most effective methods. This puts the technology past lab validation but still requiring integration into a specific production environment.
While developed under Clean Sky 2 for Ultra High Bypass Ratio engine splines, the surface treatment methods — laser hardening, micro/nanotexturing, and PVD coatings — are applicable to any crowned spline connection between shaft and gear. Wind turbine gearboxes, automotive drivetrains, and industrial machinery are natural transfer targets.
Based on the project objective, silver doping in the PVD coatings serves two purposes: controlling heat balance in the spline connection, and acting as a wear indicator — a 'smart coating' that signals when maintenance is needed. This could reduce unplanned downtime by enabling condition-based maintenance.
This is a compact, all-German consortium of 3 partners — RWTH Aachen (one of Europe's top engineering universities) leading with 1 research organization and 1 other partner. With zero industry partners and zero SMEs, this is a purely research-driven project. That's worth noting: the technology was developed in a lab and test environment, not co-developed with a manufacturer. For a business looking to adopt these methods, you would need to work directly with RWTH Aachen's WZL laboratory (their Machine Tool Laboratory, a world-renowned center for production engineering) to transfer the know-how to your production setting.
RWTH Aachen WZL (Machine Tool Laboratory) — search for CROSSONT project lead at WZL RWTH Aachen
Want an introduction to the CROSSONT team at RWTH Aachen? SciTransfer can arrange a direct meeting to discuss licensing or technology transfer for your specific spline application.
