Additively manufactured gears offer enormous potential for lighter, more efficient powertrains – but reliable design parameters have been lacking until now. The research project »Optimized 3D Gear« closes this gap through systematic investigations into lightweight structures, surface optimization, and innovative in-situ carburization.
Powder-bed-based laser beam melting (PBF-LB/M) enables the production of gears made of 16MnCr5 case-hardened steel with complex lightweight structures that could not be achieved using conventional manufacturing processes. Previous DFG research projects (short title: Generative Gear II) have already shown that weight reductions of up to 45% are possible and that additively manufactured gear teeth are, in principle, structurally sound. Nevertheless, key questions remained unanswered:
Users in industry and SMEs currently lack validated process parameters and load-bearing capacity values that would enable the reliable design of additively manufactured gears.
The project is divided into three closely interrelated research areas:
Building on existing lightweight designs, new wheel body geometries are being developed through computer-aided optimization (including Computer-Aided Optimization and bionic approaches), enabling a weight reduction of at least 60%. The static and dynamic load-bearing capacity is then experimentally validated on pulsator and stress test benches at the FZG.
Subsequent grinding and shot peening treatments (grinding, vibratory grinding, and strength shot peening) are intended to reduce surface roughness and near-surface defects. The goal is to increase the tooth root load-bearing capacity to fatigue strength values between the material grades MQ and ME.
Fraunhofer IGCV uses a multi-material process in which powders with different carbon contents (16MnCr5 + graphite particles) are selectively deposited in the powder bed. The rapid cooling during laser beam melting creates a local martensitic surface layer—without conventional carburizing in a furnace. For the first time, the goal is to achieve a case hardening depth (CHD) individually tailored to the tooth root and tooth flank and to evaluate it in terms of load-bearing capacity.
The research findings provide practical recommendations and guidelines for:
The load-bearing capacity parameters obtained are to be incorporated into standards, thereby ensuring a direct, lasting transfer of knowledge, particularly to small and medium-sized enterprises. SMEs benefit specifically from reduced investment costs (tool-free manufacturing), more flexible small-batch production, and an expanded product portfolio.
Fraunhofer Institute for Casting, Composite and Processing Technology IGCV