Epoxy infiltrated 3D printed ceramics for composite tooling applications

Recent advances in large-scale thermoplastic additive manufacturing (AM), using fused deposition modelling (FDM), have shown that the technology can effectively produce large aerospace tools with common feed stocks, costing 2.3 $/kg, such as a 20% carbon-filled acrylonitrile butadiene styrene (ABS). Large-scale additive manufacturing machines have build-volumes in the range of cubic meters and use commercially available pellet feedstock thermoplastics, which are significantly cheaper (5–10 $/kg) than the filament feedstocks for desktop 3D printers (20–50 $/kg). Additionally, large-scale AM machines have a higher material throughput on the order of 50 kg/h. This enables the cost-efficient tool production for several industries. Large-scale 3D-printed tooling will be computerized numerical control (CNC)-machined and -coated, to provide a surface suitable for demolding the composite parts. This paper outlines research undertaken to review and improve the adhesion of the coating systems to large, low-cost AM composite tooling, for marine or infrastructure composite applications. Lower cost tooling systems typically have a lower dimensional accuracy and thermal operating requirements than might be required for aerospace tooling. As such, they can use lower cost commodity grade thermoplastics. The polymer systems explored in the study included polypropylene (PP), styrene-maleic anhydride (SMA), and polylactic acid (PLA). Bio-based filler materials were used to reduce cost and increase the strength and stiffness of the material. Fillers used in the study included wood flour, at 30% by weight and spray-dried cellulose nano-fibrils, at 20% by weight. Applicable adhesion of the coating was achieved with PP, after surface treatment, and untreated SMA and PLA showed desirable coating adhesion results. PLA wood-filled composites offered the best properties for the desired application and, furthermore, they have environment-friendly advantages.

Download Full-text

Mechanical performance of lightweight ceramic structures via binder jetting of microspheres

SN Applied Sciences ◽

10.1007/s42452-021-04404-y ◽

2021 ◽

Vol 3 (4) ◽

Author(s):

Bhargavi Mummareddy ◽

Edward Burden ◽

J. G. Carrillo ◽

Kyle Myers ◽

Eric MacDonald ◽

...

Keyword(s):

Mechanical Performance ◽

Fracture Mechanisms ◽

Manufacturing Method ◽

Lightweight Structures ◽

Electromagnetic Devices ◽

Dielectric Performance ◽

Thermal Wear ◽

Composite Tooling ◽

3D Printed ◽

Binder Jetting

AbstractGeometrically-complex and lightweight ceramic parts manufactured via 3D printing are prospective structures that seem to provide excellent thermal, wear and dielectric performance. In the present work, binder jetted parts based on synthetic lightweight ceramic hollow microspheres were manufactured and evaluated under different testing conditions in order to characterize their mechanical performance. The resulting structures were assessed in terms of quasi-static flexural and compressive strength, and density. Furthermore, microscopy analyses highlighted the composition of the final structures and fracture mechanisms. The printed system mainly consisted of aluminum silicon dioxide, fly ash and traces of metal. The samples yielded similar strength as that achieved on conventional bulk-based 3D printed ceramic structures. It was observed that the strength of the printed microspheres increased by sintering the parts to near-fusion temperatures due to viscous flow of material during sintering. The combination of the proposed process and feedstock represents an attractive manufacturing method for fabricating lightweight structures for applications like composite tooling molds, electromagnetic devices, and biomedical implants.

Download Full-text