Load Carrying Capacity of Additively Manufactured Gears (PBF-LB/M, 16MnCr5) with Lightweight Optimization of Gear Hubs
Research Topic
| Short Title | Optimized 3D-Gear |
| Start of Project | Q1/2023 |
| Funding | FVA-Nr. 993/I, IGF-Nr. 22864 N/1 Federal Ministry for Economic Affairs and Climate Action, BMWK |
| Project Partner | Fraunhofer Institute for Casting, Composite and Processing Technology IGCV |
| Contact | Dr.-Ing. T. Tobie |
Project Description
Gear wheels offer great potential for lightweight construction, which can be utilized by additive manufacturing processes, among other things. Additive manufacturing can be used to produce lightweight structures in the gear wheel body that cannot be realized using conventional manufacturing methods. In the previous DFG research project "Generative Gear II", the feasibility and load carrying capacity of additively manufactured gears was extensively investigated. Here, a reproducible and highly qualified production of additively manufactured gears with different lightweight structures was achieved, resulting in a mass saving of approx. 45 % compared to comparable gears with a solid hub. While the dynamic load capacity against pitting with fatigue strength values according to ISO 6336-5 are between the material qualities MQ and ME, the fatigue strength values for the dynamic load capacity against tooth root fracture are between MQ and ML. The reason for this low material quality is considered to be near-surface pores and gas inclusions as well as the comparatively high roughness of Rz = 60 µm in the tooth root.
Based on the knowledge gained in the DFG research project "Generative Gear II", the following topics are to be addressed in the FVA research project 993 I "Optimized 3D Gear":
- Lightweight optimization
- Surface optimization
- In-situ carburization
The test gears considered in the DFG research project did not show any failure in static or dynamic tests. Thus, the lightweight construction potential has not yet been fully exhausted. Through further lightweight construction optimizations, a mass saving of approx. 60 % should be achieved in FVA 993 I compared to gears with a solid hub.
Compared to conventionally manufactured gears, the additively manufactured gears of the DFG project showed low fatigue strength characteristics against tooth root fracture. This is explained by process related surface defects. In this research project, suitable blasting and grinding processes are to be used to optimize the surface in the tooth root in such a way that fatigue strength values above the material quality MQ are achieved.
Through preliminary work at the Fraunhofer IGCV research facility, it is possible to deposit powder with different carbon concentrations. Due to an increased carbon concentration in combination with the rapid cooling during laser beam melting using PBF-LB/M, the solidified structure forms a predominantly martensitic structure. In FVA 993 I, the feasibility and viability of in-situ carburization is to be tested. If possible, a variable case hardening depth (CHD) should be realized in the tooth root and on the tooth flank.