Investigation on plastic and brittle characteristic of magnesium aluminum spinel in ultra-precision grinding

Abstract

Magnesium aluminate spinel is utilized in aerospace, optics, and electronics due to its optical properties, strength, thermal stability, and corrosion resistance. Ultra-precision grinding delivers superior surface finishing, optimal for hard and brittle substances. Surface quality after ultra-precision grinding affects optical performance significantly. In this paper, the material removal mechanism of magnesium aluminate spinel is investigated. A comprehensive method for evaluating the three-dimensional surface after ultra-precision grinding is proposed, which clearly describes the distribution of surface states. Surface error indicators are suggested for the plasticity and brittleness domain of ground surfaces. Additionally, three-dimensional surface analysis of magnesium aluminate spinel after ultra-precision grinding is performed utilizing Fourier transform. The optimized ultra-precision grinding process parameters by the firefly algorithm are obtained as n_s = 20200 r·min⁻¹, v_w = 1.2 mm min⁻¹, a_p = 1.5 μm. The mid-frequency surface roughness is 0.015 μm, and the profile height is 0.23 μm. This research achieves an optimal balance between grinding efficiency and surface quality, offering guidelines for the grinding processes for other brittle and hard materials.