Prakt. Met. Sonderband 52 (2018) 249
SCtion Moly . . , ,
19 AM) isp, All samples were printed on Raise3D 3D printer. Printer uses FDM technology, have a
) model Wir building size of 300 x 300 x 300 mm (L x W x H), minimum layer height of 10 um, filament
erp diameter of 1,75 mm and nozzle diameter of 0,4 mm. The test specimens in form of small
fe shy, disks (15 mm in diameter x 5 mm thick) were printed for measurement of magnetic
| Mana properties and metallographic examinations. Printing parameters were determined
dling Sig empirically and are summarized in Table 1.
Ve ifs So, } oT
Pati ss Tabel 1: 3D printing parameters
/achi — — _
1 pag Parameter Value
"10 ving, Layer height 300 — 100 pm
Alt Dodi Nozzle temperature 250 °C
Tolded bong Print speed 20 mm/s
¥ useful for Fill pattern Rectilinear
Tctwitngy 1 Fill density 100%
Onder ang Bed temperature 60°C
LM) to prödun Sa
amet, ty The resulting magnetic properties were measured by a permeagraph (Magnet Physik
8 B Nm Steingroever). The microstructure of the 3d printed polymer bonded magnets was examined
ring base on the transversal cross-section on the metallographic samples with an optical microscope,
“laments oe Nikon Epiphyte 300, equipped with a system for digital quantitative image analysis (Olympus
“cessed. DB12 and software program Analysis). Before metallographic preparation the samples were
positioned using metal clamps and carefully cold mounted in epoxy resin. Cold mounting is
preferable because of relatively low melting temperature of PA12 which could lead to
deformation or even melting of the samples if using hot mounting procedures. Grinding was
performed using SiC papers P320, P500, P1000, P2500, and P4000. Followed by polishing
ommercial me! using 1micron diamond suspension and the final step were polishing using 0,05-micron
wder. The MO colloidal alumina. In both polishing steps a micro-cloth was used which was wetted prior to
orphology wi applying the polishing agent for additional lubrication. Samples were prepared on an
C fuX and hig automated grinder//polisher, using clockwise rotation 250/40 rpm, and a force of 10N, expect
nel 18 produce at the final step where the force was reduced to 5N. Additionally, the morphology melts spun
q process af NdFeB powder was examined with the scanning electron microscope FEI Siron NC.
BH) raz 12
"der the PAY
verage pad 3. RESULTS AND DISCUSSION
ability, thema
nets. the MO The magnetic properties of polymer bonded magnets are strongly dependent on size,
ent by sing shape, type, concentration and dispersion of magnetic powder in the polymer matrix. On
5 solution wa other hand are the mechanical properties additionally also influence by matrix properties
°C for 2hous and interfacial adhesion between the magnetic powders and polymer matrix. As long as the
red to achie size and the distribution of rapidly quenched powders are within the right range, high
C. The desire magnetic properties of polymer bonded magnets can be obtained. This is mainly because
Iubricants ng the Nd-Fe-B ribbons have high hardness and plate-like shape. The larger the size of rapidly
> and polyme quenched ribbons is, more difficult is to obtain high density of bonded magnets. However,
er Hlending ¢ the structure will be destroyed if the size is too small, which results in the deterioration of
3 gem To magnetic properties. It was shown in literature, that the bimodal particle size distribution of
rad using 6 the powders enables achievement of high loading factors and lower melts viscosity by
naration of injection moulding of bonded magnets [4].
