Optimizing Multi-Head FDM 3D Printing

International researchers are delving further into FDM 3D printing, investigating details that have an impact on prints, with their findings outlined in the recently published ‘Optimizing Design Patterns for Multi-Head Fused Deposition Modeling (FDM) Systems.’

In this study, the team made up of researchers from the National Agency for Science and Engineering Infrastructure (NASENI) in Nigeria and Texas A&M University, experimented with numerous settings and patterns, such as:

• Nozzle diameter
• Extrusion width
• Layer thickness

Patterns were then tested for:

• Appearance/surface finish
• Strength
• Speed
• Stiffness of composite materials

“The quality and mechanical properties of a FDM print are largely dependent on several print parameters and process variables,” state the researchers. “For a single head printer, the strength and stiffness of the print prototype is low. This led to the need to improve the strength and stiffness of print prototypes for improved quality and mechanical properties.”

Using a UprintPlus 3D printer, researchers created four test blocks in a range of shapes and sizes for both calibration and simulation. Upon investigating calibration, the team inspected both layer thickness and model interior type, whether solid or sparse fill.

“The ‘real improvements in quality’ in terms of Volume Fraction percentage fills were determined for all layer patterns. Volume Fraction is very important role in determining the quality of material parts,” stated the researchers. ‘Volume Fraction’ is a mathematical element that shows the percentage of bead volume that fills the entire volume of a 3D printed model. It may also be referred to as the ‘percentage volume fill.’

ABS material was used for testing, with the test samples created in SolidWorks and then imported into CatalystEX and Simplify3D.

“Of major importance in the calibrated results was the print quality as a function of the print time and print quality as a function of the volume fraction and time put together. The results obtained helps to get the real quality of prints on FDM processes,” explained the research team.

Sizes for each test block were carefully thought out—and while dimensions varied, thickness remained the same for each.

Dimensions of test blocks

Volume fraction ranged from 55 to 96 percent throughout the study, depending on the type of model interior. Solid interiors exhibited the highest volume fill—meaning few voids and greater strength and durability.

“Block 3 had the best volume fraction for both layer thicknesses at solid interior fill. The solid interior fill showed the highest volume fill available which means that there are little or no voids in the printing. Fewer voids mean better strengths and stiffness and more durable parts,” concluded the researchers. “This was confirmed by simulation of all blocks. It also showed the best surface finish for all types of fill. Printing with small layer thickness produced higher build times but stronger prints. This goes to prove that print quality of a 3D printed part is a function of the volume fraction and time put together.”

Possibly the most ubiquitous form of 3D printing, FDM techniques abound—and they are also continuing to be studied around the world, sometimes integrated with other technologies like SLA, compared with PolyJet, and experimented with regarding color, mechanical properties, and more.

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