Raster angle impact on FDM-based additive manufactured fluidic oscillator

The interior surface of a fluidic oscillator produced by FDM (Fused Deposition Modeling)-based additive manufacturing is associated with a directional pattern corresponding to the 3D printing raster angle. The present research explores the impact of raster angle α=0, 45, and 90° from three commercial 3D printers versus a CNC machined oscillator. The surface is characterized using an optical 3D measurement system. The performance of the emanated jet is assessed using hot-wire anemometry downstream of the outlet nozzle, and the required supply pressure is measured at the actuator inlet. Printer P₁ with an actuator average roughness S̄_a=8.3 μm and printer P₂ with S̄_a=29.9 μm inherit clear raster patterns while actuators printed by printer P₃, more economical compared to printer P₁, do not exhibit an evident pattern related to raster angle with S̄_a=17.7 μm. Regardless of the type of printer and associated surface texture, oscillators with 0° raster angle provoke higher jet spreading accompanied by a lower required supply pressure compared to the milled sample. Strikingly, the performance for P₃⁰ and P₃⁹⁰ is noticeably superior to the other printed oscillators and surpasses the milled actuator in terms of jet switching quality. Power-law fit is depicted to estimate the jet spreading versus surface roughness for each raster angle.