Effects of Spreading Parameters on Powder Bed Quality

Öz

Powder bed-based additive manufacturing processes such as laser powder bed fusion, binder jetting, and electron beam melting are commonly utilized in various critical areas such as medical, aviation, and energy. Common to all these operations, the powders are first spread onto the build platform in a layer-by-layer fashion and selectively fused or bound with a suitable method. The quality of the process depends on several parameters, including how the powders are spread onto the build platform. The powder spreading operation, which involves spreading powders on a powder bed with a roller or spreader, is an important step in these operations and can affect various process outputs. In this study, powder spreading is numerically investigated using the discrete element method to determine the effects of layer thickness, rotation, and translation velocities, selected as parameters with a powder spreader roller. To account for the relationship between powder spreading parameters and the powder volume packing fraction, as well as the interactions between particles themselves and between the particles and the build plate, the Hertz-Mindlin contact model, including normal tangential forces, as well as the Johnson-Kendall-Roberts (JKR) contact model, including the effects of surface energy, were added to the numerical model. A Design of Experiment combined with analysis of variance (ANOVA) was utilized to gain a broader understanding of the relationship between process parameters, green density, and dynamic angle of repose.

Anahtar Kelimeler

• Additive Manufacturing
• Powder Spreading
• Dicreate element Method
• ANOVA

Toz Serme Parametrelerinin Toz Yatağı Kalitesine Etkileri

Öz

Lazerle toz yatağında füzyon, bağlayıcı püskürtme ve elektron ışını ile ergitme gibi toz yatağı tabanlı yöntemler, tıbbi, havacılık ve enerji gibi çeşitli kritik alanlarda yaygın olarak kullanılmaktadır. Bu işlemlerin hepsinde ortak olarak, tozlar önce katman üretim platformuna yayılır ve uygun bir yöntemle seçici olarak ergitilir veya bağlanır. Sürecin kalitesi, tozların üretim platformuna nasıl yayıldığı da dahil olmak üzere birçok süreç parametresine bağlıdır. Bir merdaneyle veya yayıcı ile tozların toz yatağına serilmesi işlemi olan toz yayma operasyonu, bu işlemlerde önemli bir adımdır ve yoğunluk, yüzey pürüzlülüğü gibi çeşitli süreç çıktıları üzerinde etkili olabilir. Bu çalışmada, toz yayma, katman kalınlığı, dönüş ve geçiş hızlarının parametre olarak seçildiği bir toz yayıcı silindiri ile, ayrık elemanlar yöntemi kullanılarak sayısal olarak incelenmiştir. Toz yayma parametreleri ile toz hacim paketleme oranı arasındaki ilişki, partiküllerin kendileri arasında ve partikül ile üretim plakası arasındaki etkileşimleri dikkate almak için normal ve teğetsel kuvvetleri içeren Hertz-Mindlin temas modelinin yanında yüzey enerjisinin etkilerini içeren Johnson-Kendall-Roberts (JKR) temas modeli sayısal modele eklenmiştir. Deney Tasarımı ve varyans analizi (ANOVA) ile birleştirilmiş olarak, süreç parametreleri ile yoğunluk ve dinamik yığın açısı arasındaki ilişkiyi daha geniş bir anlayış kazanmak için kullanılmıştır.

Anahtar Kelimeler

• Eklemeli imalat
• ANOVA
• Toz Serpme
• Ayrık elemanlar metodu

Kaynakça

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