Controlling the flow: morphology matters in powder-bed AM

經過 John Duffy, Friday, 24th February 2023

If you’re a fan of Italian food, you’ll know that there are more types and shapes of pasta than most of us can hope to learn by heart. From bucatini (similar to spaghetti, but with a hole through the middle) to amori spirals, conchiglie shells and tiny stelle you might find in soup, each is still certainly pasta – but will perform very differently if you add sauce!

To stay with the pasta metaphor a little longer, imagine you were trying to make a delicious meal, but all these different shapes and sizes of pasta were mixed up together. It would be tricky, because your spaghetti would stand up in the pan while your stelle sank to the bottom and cooked very quickly.

Size and shape matter

So, why are we talking about pasta? It’s a good metaphor to explain why particle size and particle shape are so important – especially when you’re trying to make a single cohesive product, like in metal powder-bed additive manufacturing (AM). If your powder doesn’t have a consistent size distribution or consistent particle morphology – or if you don’t understand these characteristics at all – you can’t accurately predict the final properties and performance of your finished product. Your powder’s flowability performance will be unpredictable. When making a safety-critical part, for example, this is a big problem.

But even when you have measured particle size and shape, what do you do with that data? It takes a lot of experience and knowledge to pinpoint exactly what the ideal size or shape distribution is for a specific application.

Setting the standard

That’s where the experts come in! The Materials Processing Institute has established some in-house definitions, classifying metal powders into morphological groups using geometric descriptors. In experiments, these group classifications were found to correlate strongly with the flowability parameters of metal powders – giving them real-world relevance for manufacturers looking to implement better quality control. The outcomes of these experiments were also carefully compared with the mechanical tests carried out on the finished AM products.

The researchers at the Materials Processing Institute used Malvern Panalytical’s Morphologi 4 particle imaging solution to categorize powders reliably into the different morphological groups that they defined. A benefit of the Morphologi 4 – and the classifications themselves – is that they are not only applicable to metal powders, but also to other powder materials such as cement, polymers and ceramic.

Become an application expert

This wider scope means that a variety of industry professionals, from suppliers to manufacturers and analytical specialists, should attend our upcoming webinar on how to apply this research in practice!

On March 14, a t 16:30 CET, we’ll be hearing from Ehsan Rahimi, Senior Researcher at the Materials Processing Institute. Ehsan will explain how the morphological approach can upgrade real-world processes across the powder-bed AM value chain by improving quality and helping industry professionals to make better decisions about their input materials.

Register here now and save your spot for March 14!

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