On the oxidation resistance of sinusoidal microstructure fabricated by elliptical vibration cutting

Abstract

The sinusoidal microstructure fabricated by the conventional slow tool servo (STS) cutting has low oxidation resistance and large fluctuation of surface roughness, which affects fluid instability in Rayleigh–Taylor experiments. This study is devoted to reducing roughness fluctuation and improving the oxidation resistance of sinusoidal microstructure by adopting the elliptical vibration (EV) of tool in the STS cutting. First, the kinematic principle of EVSTS cutting is demonstrated by highlighting the time-varying orientation of the elliptical tool trajectory relative to instantaneous nominal cutting velocity. Next, the geometric roughness model of sinusoidal surface is developed to analyze the roughness fluctuation along the wavelength direction. Then, flat surface cutting and accelerated oxidation experiments are performed to explore the deterministic effects factors on machined surfaces' surface roughness and oxidation resistance using elliptical vibration cutting (EVC). The experimental results show that the EVC can reduce the oxide thickness of the machined surface after accelerated oxidation by 35 % on average, owing to the reduced roughness and surface strengthening effects. The effects of the vibration trajectory, edge radius, and wavelength-direction nominal cutting velocity on the surface roughness and surface oxidation resistance are established. Finally, the processing parameters for the EVSTS cutting of sinusoidal microstructure are optimized by further considering the time-varying orientation of the elliptical tool trajectory. Surface texturing tests with results demonstrates that the EVSTS can significantly improve the oxidation resistance of the microstructured surface, suppressing the roughness fluctuation along the wavelength direction by 25–60 %.