Particle analysis applied to additive manufacturing raw materials
This article focuses on the effect of particle size on the additive manufacturing process.
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What is 3D printing?
3D printing, often known as additive manufacturing, is a popular type of manufacturing technique. This technique is based on CAD model files and uses adhesive substances such as powdered plastic or metal to produce three-dimensional objects layer by layer.
Additive manufacturing materials include thermoplastics like acrylonitrile butadiene styrene (ABS), metallic substances (especially powders), varnishes and porcelain. ISO/ASTM 52900 additive manufacturing has classified 3D printing operations into seven distinct classes. These include binder jetting, material extrusion, powder bed fusion, sheet rolling, VAT curing, direct energy deposition and material jetting.
Sintering, fusion and stereolithography are the three main forms of 3D printing techniques. To manufacture high resolution products, sintering is a method in which heat is applied to the substance but not until melting.
Powder bed fusion, electron beam fusion and direct energy deposition are 3D printing fusion processes that use laser beams, electric sparks or electron beams to print objects in melting the components together at extreme temperatures. Photopolymerization is used in stereolithography to produce components. This method uses the appropriate light source to selectively contact the material to heal and crystallize a cross-sectional area of the product into thin sheets.
Significance and industrial use
3D printing is one of the most transformational new methods of our time, used to generate a highly accurate virtual model that is especially useful in the aviation and automotive industries. It has a wide range of applications, integrating wearable technology with multiple biological capabilities and other biomedical applications, such as custom implantable devices.
It is commonly used in mold making, product engineering, and other disciplines. Printing components with this technique is typical these days, and it is rapidly overtaking other techniques that were used before. Jewelry, apparel, structural engineering, architecture, construction and design, dental and medical sectors, spatial analysis and geotechnical work are just a few of the industries and applications.
More from AZoM: Laser Diffraction Particle Size Analysis of Cement
If additive manufacturing is one of the best known processes, it has several restrictions in its uses. Low production throughput and associated costs are significant factors limiting the use of AM. Although 3D printing can make products from a variety of polymers and metals, the accessible raw materials are not exhaustive.
Indeed, not all metals or polymers can be sufficiently thermally regulated to allow 3D printing. Additionally, due to changing manufacturing techniques, 3D printed products may differ in size from CAD models. Additionally, unlike more traditional processes like compression molding, where high volumes can be more cost efficient in production, 3D printing has a fixed cost.
Factors Affecting Additive Manufacturing
Many variables influence the efficiency of 3D printing. Some are entirely material related, although overall quality can also be affected by material performance, cutting ability, and various other factors. The grain size, sphericity, chemical characteristics, oxygen concentration, and mobility of the powdered substance all impact the performance indicators of 3D printed parts.
Additionally, layer thickness and temperature also greatly affect the quality of 3D printed materials. In the remainder of this article, emphasis will be placed on the particle size and roundness of the particles used for the process.
Traditional particle size and roundness data in 3D printing
Currently, powder material particle sizes widely used in metal 3D printing include 15-53 μm, 53-105 μm, and in some circumstances 105-150 μm.
The particle size range to be used is determined by the power sources used by the metal printer. Printers that use lasers as the power source are acceptable for use due to their fine focus point and the ease with which they can dissolve finer particles, and the average powder size of 15-53 μm is suitable for use. When dissolving coarse material and using 53-105μm powder, a plasma beam can be used as a power source for the printer.
Roundness is a description of how close particles of powdered material are to a circle, with a value ranging from 0 to 1, with ideal spherical grains having a value of 1. A substance’s ability to flow easily is defined as fluidity, and its value is assessed by the time required for a specific amount of powder particles to flow through a measuring instrument with a given aperture (s/50g).
In general, the higher the sphericity value, the greater the flowability of the metal powder. As a result, it is easier to regulate layering and particle flow when metal 3D printing, which improves the print quality of components.
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Nickel Alloy Raw Material Particle Size Analysis
The research of Mr. Du and his team in the Journal of Manufacturing Science and Engineering showed that mixtures made up of different particles can achieve better compressibility than their constituent particles, and that there was an ideal mixing percentage to produce the highest packing density of the mixture. A higher maximum packing density of the mixture was achieved by having a lower component particle size ratio (fine to coarse) and a higher component packing density ratio (fine to coarse). There was a component stacking density ratio threshold beyond which the blending approach was ineffective for density enhancement. As the mass fraction of tiny particles increased, the flowability of the powder deteriorated, causing powder feeding issues and, therefore, affecting the stability of 3D printing.
The roundness of the particles is another essential aspect. Since spherical or sub-spherical powder is more fluid, it is less likely to clog the powder delivery mechanism during printing. Additionally, the spherical powder is easier to distribute in a thin layer, improving the dimensional accuracy and surface integrity of 3D printed products. In addition, the density and homogeneity of the components increase, making spherical powders the preferred raw material for 3D printing.
In summary, to maintain the competitive advantage of AM, careful control and analysis of particle dispersion and roundness is required to deliver higher quality output.
References and further reading
Best size, 2022. The importance of particle size and roundness analysis for 3D printing. [Online]
Available at: https://www.bettersizeinstruments.com/the-importance-of-particle-size-and-roundness-analysis-for-3d-printing.html
Du, Wenchao et al. Additive manufacturing by binder projection: effect of particle size distribution on density. 2021. Journal of Manufacturing Science and Engineering 143(9). Available at: https://asmedigitalcollection.asme.org/manufacturingscience/article-abstract/143/9/091002/1100582/Binder-Jetting-Additive-Manufacturing-Effect-of?redirectedFrom=fulltext
Thakkar, Rishi, et al. 2021. Impact of laser speed and drug particle size on selective laser sintering 3D printing of amorphous solid dispersions. Pharmacy 13(8). 1149. Available at: https://www.mdpi.com/1999-4923/13/8/1149
Gao, MZ, Ludwig, B., and Palmer, TA 2021. Impact of Atomizing Gas on Characteristics of Austenitic Stainless Steel Powder Raw Materials for Additive Manufacturing. Powder technology. 383. 30-42. Available at: https://www.sciencedirect.com/science/article/pii/S0032591020311669?via%3Dihub
Wang, DW, et al. 2022. Inheritance of Microstructure and Mechanical Properties in Laser Powder Bed Fusion Additive Manufacturing: A Raw Material Perspective. Materials Science and Engineering: A. 832. 142311. Available at: https://doi.org/10.1016/j.msea.2021.14231