Orthopaedic regenerative medicine requires the design of scaffolds and implants that replicate the biomechanical properties of bones. Porous implants, designed with bespoke mechanical performance using state-of-the-art of topology optimization and produced by additive manufacturing, are suitable candidates for repairing or replacing damaged bones.
A few months ago, we were wondering about process control in powder bed fusion of reactive powders. What are the impacts of particles’ surface contamination on the fabrication of metal components? And what are the best ways to minimise it during the complete manufacturing cycle?
Then, very few studies were trying to assess the impact of powder particles surface chemistry on the process (powder spreading, melt wettability, pores formation, etc…) and on the final product characteristics (relative density, etc).
As more data get publicly available, we can present the results of a detailed investigation aiming to 1) understand the effects of powder surface chemistry, 2) minimise particles surface contamination on the finished products and 3) improve SLM process control.
Effect of particles size distribution and packing density on the formation of balling defects during SLM of In718
Balling is a defect that can occur when the molten pool created during selective laser melting (SLM=L-PBF) becomes discontinuous and breaks into separated islands. In this post, we report and discuss how the powder particle arrangement impact the bead geometry and formation of balling defects during SLM.
Direct Laser Deposition (DLD) is a type of laser-based additive manufacturing process used to create functional metal components layer by layer using a sliced 3D CAD (computer aided drawing) file. Unlike Selective Laser Melting which utilizes a bed of powder metal that is ‘selectively’ melted via a laser, DLD is based on melting feedstock (blown powder or wire) at the focus point of a laser source. In this post, we address the residual stresses occurring during the build of metal components with DLD technology .
Nickel-based superalloys have great applications in the fabrication of turbine blades, jet engines, and other high-value metal components found in marine applications, industrial or nuclear reactors. Using additive manufacturing technology to build these components can offer significant benefits. However, the laser processability of these alloys shows they are prone to cracking.
Powder production routes, actual AM process and recycling methods all influence particles characteristics. In powder bed fusion, these properties affect the homogeneity and density of the powder layers spread across the build platform and, in turn, the process repeatability and the parts quality. Quantifying a combination of factors defining a ‘good’, process-able powder is still required for AM. Yet little has been studied to link traditional powder measurements to its flowability and to its AM process-specific spreading abilities. In this post, let’s discuss suitable parameters and values to qualify flowability of metal powders for selective laser melting (SLM).
Obtaining high density components is a trade-off between build rate and powder irradiation time (ie scanning speed). Achieving high density is usually the 1st step in parameters development for SLM and EBM. But do we have to assume (close to) 100% density to obtain satisfactory mechanical properties? This blog post addresses the impact of defects obtained in SLM on mechanical properties of Ti64.