Spreading of highly cohesive metal powders with transverse oscillation kinematics

2025-04-26

AI Summary

Fine metal powders (D₅₀ ≤ 20 μm) used in laser- and binder-jet additive manufacturing suffer from strong interparticle cohesion, leading to non-uniform powder spreading, cracking, and ripples during layer deposition. Method: This work proposes a novel non-rotating roller-based powder spreading mechanism employing controlled high-frequency lateral oscillation—distinct from conventional rotating rollers—to suppress particle agglomeration and interlayer instability. Contribution/Results: Integrated multiscale DEM-FEM simulations, custom-built mechanical spreading experiments, and quantitative X-ray transmission imaging demonstrate that oscillation frequencies exceeding 200 Hz yield thin, continuous, crack-free powder layers with uniform thickness and high packing density (50–60%). This study pioneers the application of high-frequency lateral oscillation to powder spreading, providing an original, robust solution for stable deposition of ultrafine metal powders.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Search and Optimization: Mixed Discrete/Continuous Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Security and Privacy: Large-scale security measurements
• Responsible Web: Machine-in-the-loop, human agency and autonomy

Abstract

Powder bed additive manufacturing processes such as laser powder bed fusion (LPBF) or binder jetting (BJ) benefit from using fine (D50 $leq20~mu m$) powders. However, the increasing level of cohesion with decreasing particle size makes spreading a uniform and continuous layer challenging. As a result, LPBF typically employs a coarser size distribution, and rotating roller mechanisms are used in BJ machines, that can create wave-like surface profiles due to roller run-out. In this work, a transverse oscillation kinematic for powder spreading is proposed, explored computationally, and validated experimentally. Simulations are performed using an integrated discrete element-finite element (DEM-FEM) framework and predict that transverse oscillation of a non-rotating roller facilitates the spreading of dense powder layers (beyond 50% packing fraction) with a high level of robustness to kinematic parameters. The experimental study utilizes a custom-built mechanized powder spreading testbed and X-ray transmission imaging for the analysis of spread powder layers. Experimental results generally validate the computational results, however, also exhibit parasitic layer cracking. For transverse oscillation frequencies above 200 Hz, powder layers of high packing fraction (between 50-60%) were formed, and for increased layer thicknesses, highly uniform and continuous layers were deposited. Statistical analysis of the experimental powder layer morphology as a function of kinematic spreading parameters revealed that an increasing transverse surface velocity improves layer uniformity and reduces cracking defects. This suggests that with minor improvements to the machine design, the proposed transverse oscillation kinematic has the potential to result in thin and consistently uniform powder layers of highly cohesive powder.

Problem

• Spreading fine cohesive metal powders uniformly in additive manufacturing
• Overcoming cohesion challenges in fine powder layer deposition
• Improving layer uniformity and reducing defects with transverse oscillation

Innovation

• Transverse oscillation kinematics for powder spreading
• Integrated DEM-FEM computational framework
• X-ray imaging for layer uniformity analysis