Polymer-bonded anisotropic SrFe12O19 filaments for fused filament fabrication

Abstract

In this publication we describe the extrusion process and the properties of polymer-bonded anisotropic SrFe12O19 filaments for fused filament fabrication (FFF). Highly filled polyamide 12 filaments with a filling fraction from 40 vol.% to 55 vol.% are mixed and extruded into filaments with a diameter of 1.75 mm. Such filaments are processable with a conventional FFF 3D printer. No modifications of the 3D printer are necessary. Detailed mechanical and magnetic investigations of printed samples are performed and discussed. In the presence of an external alignment field, the Sr ferrite particles inside the PA12 matrix can be aligned along an external magnetic field. The remanence can be increased by 40 % by printing anisotropic structures. For the 55 vol.% filled filament, a remanence of 212.8 mT and a coercivity of 307.4 mT are measured. The capabilities of printing magnetic anisotropic structures in a complex external field are presented with a Halbach-array arrangement. By the aim of an inverse field model, based on a finite element method, the orientation of the particles and the quality of the print can be estimated by a nondestructive method.

3D Printing of ABS Barium Ferrite Composites

“…Powder bed fusion can also be used for the additive manufacturing of magnets using a NiMnGa alloy [38]. In contrast to the above listed values described in literature, the obtained experimental results are moderate, if one compares for example the measured remnant flux density of 47 mT (at 35 vol.%) with the 102 mT (at 40 vol.% strontium ferrite in PA12), described in reference [33], which can be attributed to the poor sample quality.…”

“…Recent results describes FFF of strontium ferrite, dispersed in polyamide 12 up to a solid load of 55 vol.%, printed on the surface on an alignment magnet (NdFeB), which enhances the magnetic properties due to external orientation in z-direction. Remnant magnetic flux densities around 178 mT for a solid load of 40 vol.% and 213 mT for 55 vol.% could be achieved [33]. Without external magnetic field orientation values around 102 mT (40 vol.%) and 149 mT (55 vol.%) were measured [33].…”

“…Remnant magnetic flux densities around 178 mT for a solid load of 40 vol.% and 213 mT for 55 vol.% could be achieved [33]. Without external magnetic field orientation values around 102 mT (40 vol.%) and 149 mT (55 vol.%) were measured [33]. Wei et al investigated the magnetic properties of barium and strontium ferrite, dispersed in a polyvinylalcohol/polyethylene-glycol (PVA/PEG) binder, applying a syringe-type 3D printing process and different ferrite treatment strategies [34].…”

Advances in 3D printing of magnetic materials: Fabrication, properties, and their applications

“…Importantly, the impact of an external magnetic field was investigated during the printing process [59,143,150]. Nagarajan et al [143] developed particle alignment configuration for material jetting 3D printing process using real-time optical microscopy as indicated in Fig.…”

Open Source Filament Diameter Sensor for Recycling, Winding, and Additive Manufacturing Machines

“…In industry, laser multi-axis contactless meters are used to control the diameter of the winding filament. This allows measuring from different angles and tracking the ovality and diameter deviations (Huber et al, 2020). The independent open source community often cannot afford to use such expensive tools.…”