Up to one third of the production cost of an additive manufacturing (AM) component produced by powder bed processes (particularly metals) is the cost of the powder used, with commercial viability resting on a robust supply chain and effective powder recycling strategies. More importantly, the chemical and physical properties of the powder directly impact the build process and final component quality and must be controlled and optimized to ensure process robustness and consistency. To achieve this powder properties must be characterized at various stages in the supply chain, from new alloy development through to powder recycling. Laser diffraction, automated image analysis, X-ray fluorescence and X-ray diffraction are four key analytical techniques that are commonly used to characterize additive manufacturing powders.
Particle size distribution is critical for powder bed additive manufacturing processes since it affects powder bed packing and flowability which in-turn impacts on build quality and final component properties. Laser diffraction is an established technique for measuring the particle size distribution of metal, ceramic and polymer powders for additive manufacturing, and is employed by powder producers, component manufacturers and machine manufacturers worldwide to qualify and optimize powder properties for their customers and processes. Laser diffraction can provide a complete high-resolution particle size distribution in a matter of minutes using either wet or dry dispersion techniques. The technique can also be integrated into a process line to provide real-time particle sizing during a sieving or atomization process for example.
Automated Image Analysis
Products: Morphologi 4
Powder bed density and powder flowability are directly, though not exclusively, influenced by particle size and shape. Particle morphology is therefore, another important metric for powder bed additive manufacturing, with smooth, regular-shaped particles preferable as they can flow and pack more easily than those with a rough surface and irregular shape. Automated static image analysis can be used to classify and quantify the size and shape of metal, ceramic and polymer powders by combining particle size measurements such as length and width, with particle shape assessments such as circularity and convexity on a statistically representative sample (>10,000 particles).
X-ray fluorescence (XRF) is routinely used by metal powder producers and component manufacturers for determining the elemental composition of metal alloys and for detecting the presence of contaminants or inclusions. Elemental composition is particularly important for alloys since small variations in the concentration of alloying elements can affect chemical and physical properties, including strength, hardness, fatigue life, and chemical resistance. XRF can meet the standard requirements for determining alloy composition (e.g. ASTM E2465-13) while providing considerable time and cost savings compared with alternative techniques.
X-ray diffraction (XRD) is a non-destructive analytical technique that provides information about the micro-structural characteristics of metal, ceramic and polymer powders and their fabricated components, such as phase composition, crystallite size, texture (crystallite orientation) and residual stress/strain. These characteristics can be influenced by thermal and mechanical processes such as atomization, laser melting, and powder pressing and can affect properties such as hardness, strength and fatigue life.
What can these techniques do for you?
On 22nd October Malvern Panalytical will be organizing a free webinar covering each of the above technologies and their relevance to additive manufacturing. The webinar ‘Characterizing Material Properties for Additive Manufacturing’ will be jointly-presented by four of Malvern Panalytical’s in-house specialists and will provide an overview of the four techniques mentioned and how they can be used to measure and optimize the chemical and physical properties of AM powders and components. Speakers include;
- Anne Virden, Technical Support Supervisor – Laser Diffraction & Imaging at Malvern Panalytical in Malvern, United Kingdom.
- Robert Taylor, Product Technical Specialist – Analytical Imaging at Malvern Panalytical in Malvern, United Kingdom.
- Marco Sommariva, Team Leader XRD in the Malvern Panalytical Application Competence Center in Almelo, The Netherlands.
- Armand Jonkers, Application Specialist XRF in the Malvern Panalytical Application Competence Center in Almelo, The Netherlands.