Investigating the Sensitivity of Particle Size Distribution on Part Geometry in Additive Manufacturing

Metal powders suitable for use in powder bed additive manufacturing processes should ideally be spherical, dense, chemically pure and of a specified particle size distribution. Ti6Al4V is commonly used in the aerospace, medical and automotive industries due to its high strength-to-weight ratio and excellent corrosion resistance properties. Interstitial impurities in titanium alloys have an impact upon mechanical properties, particularly oxygen, nitrogen, hydrogen and carbon. The plasma spheroidisation process can be used to spheroidise metal powder consisting of irregularly shaped particles. In this study, the plasma spheroidisation of metal powder was performed on Ti6Al4V powder consisting of irregularly shaped particles. The properties of the powder relevant for powder bed fusion that were determined included the particle size distribution, morphology, particle porosity and chemical composition. Conclusions were drawn regarding the viability of using this process to produce powder suitable for additive manufacturing.

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Preparation and Properties of Spherical Mo Powders by Plasma Rotating Electrode Process for Additive Manufacturing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.993.391 ◽

2020 ◽

Vol 993 ◽

pp. 391-397 ◽

Cited By ~ 1

Author(s):

Sha Qiu ◽

Bin Ke Chen ◽

Chang Shu Xiang

Keyword(s):

Particle Size ◽

Additive Manufacturing ◽

Particle Size Distribution ◽

Size Distribution ◽

Electrode Process ◽

Utilization Rate ◽

Molybdenum Powder ◽

High Quality ◽

Rotating Electrode ◽

Process Method

Since molybdenum has very high melting point of 2620 °C, there are many difficulties in its forming and post-processing, especially for deep processing. Furthermore as molybdenum is expensive, the utilization rate is important for the molybdenum processing. Additive manufacturing can directly manufacture the parts without mold and increase the utilization rate, and brings an opportunities for the new direction of deep processing for molybdenum. Due to the high quality requirements of molybdenum powder in additive manufacturing technology, the high-quality spherical molybdenum powder was prepared by plasma rotating electrode process method in the present study. The morphology, particle size and particle size distribution, chemical and physical properties were investigated. The molybdenum powder prepared by plasma rotating electrode process method showed to have high purity, high sphericity, good fluidity and high bulk density, proper particle size distribution and low gap element within the powder. The microstructure of the powder was a mixed structure of dendrites and cell crystals formed by rapid solidification, and as the particle size of the powder gradually decreased, the microstructure of the powder surface was remarkably refined. Within a certain range, the molybdenum powder with a wide particle size distribution had better fluidity and higher bulk density. The high-quality spherical molybdenum powder was prepared by plasma rotating electrode process method, which can meet the requirements of additive manufacturing technology for powder material performance.

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Investigating the Sensitivity of Particle Size Distribution on Part Geometry in Additive Manufacturing

Volume 2B: Advanced Manufacturing ◽

10.1115/imece2020-23816 ◽

2020 ◽

Author(s):

Vaishak Ramesh Sagar ◽

Samuel Lorin ◽

Johan Göhl ◽

Johannes Quist ◽

Christoffer Cromvik ◽

...

Keyword(s):

Particle Size ◽

Additive Manufacturing ◽

Particle Size Distribution ◽

Size Distribution ◽

Complex Geometry ◽

Structural Mechanics ◽

Raw Material ◽

Test Bed ◽

Powder Bed ◽

Melted Zone

Abstract Selective laser melting process is a powder bed fusion additive manufacturing process that finds applications in aerospace and medical industries for its ability to produce complex geometry parts. As the raw material used is in powder form, particle size distribution (PSD) is a significant characteristic that influences the build quality in turn affecting the functionality and aesthetics aspects of the end product. This paper investigates the effect of PSD on deformation for 316L stainless steel powder, where three coupled in-house simulation tools based on Discrete Element Method (DEM), Computational Fluid Dynamics (CFD), and Structural Mechanics are employed. DEM is used for simulating the powder distribution based on the different particle size distribution of the powder. The CFD is used as a virtual test bed to determine thermal parameters such as density, heat capacity and thermal conductivity of the powder bed viewed as a continuum. The values found as a stochastic function of the powder distribution is used to test the sensitivity of the melted zone and distortion using Structural Mechanics. Results showed significant influence of particle size distribution on the packing density, surface height, surface roughness, the stress state and displacement of the melted zone. The results will serve as a catalyst in developing geometry assurance strategies to minimize the effect of particle size distribution on the geometric quality of the printed part.

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Impact of Bimodal Particle Size Distribution Ratio of Functional Calcium Carbonate Filler on Thermal and Flowability Properties of Polyamide 12

Applied Sciences ◽

10.3390/app11020641 ◽

2021 ◽

Vol 11 (2) ◽

pp. 641

Author(s):

Fabio Ippolito ◽

Gunter Hübner ◽

Tim Claypole ◽

Patrick Gane

Keyword(s):

Particle Size ◽

Additive Manufacturing ◽

Calcium Carbonate ◽

Particle Size Distribution ◽

Size Distribution ◽

Crystallization Behavior ◽

Filler Particle ◽

Melt Flow ◽

Polyamide 12 ◽

Carbonate Filler

In previous investigations, it was shown that the melting, as well as crystallization behavior of polyamide 12, could be manipulated by adjusting the particle size distribution of calcium carbonate as a functional filler. It was demonstrated that the melt properties of this compound show a significant dependency on the filler volume-based particle size. As finer and narrower the calcium carbonate particles in the polymer matrix become, the less influence the filler has on the melting properties, influencing the melt flow less significantly than the same surface amount of broad size distribution coarse calcium carbonate filler particles. However, due to increased nucleation, the crystallization behavior on cooling showed a markedly more rapid onset in the case of fine sub-micrometer filler particle size. To control further and optimize the thermal response properties of a filling compound for improved properties in additive manufacturing processing through selective laser sintering, the possibility to combine precisely defined particle size distributions has been studied, thereby combining the benefits of each particle size range within the chosen material size distribution contributes to the matrix. The melt flow at 190 °C, the melting speed, melting and crystallization point as well as crystallization time at 170 °C were analyzed. The thermal and flow properties of a polyamide 12 matrix can potentially be optimized with a combination of a precise amount of coarse and fine calcium carbonate filler. The improvements were exemplified using a twin-screw extruder for compounding, indicating the potential for optimizing functionally filled polymer in additive manufacturing.

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