A novel anisotropic assessment method for nanometric surface roughness of ultra-precision diamond milling

Ultra-precision diamond milling (UPDM) is one of ultra-precision machining approaches, providing nanometric surface roughness (NSR). The NSR exhibits rich anisotropic features, which is very sensitive to noise. However, there is lack of effective assessment of the anisotropic NSR. Therefore, the study proposed surface difference and surface curvatures as extra parameters to estimate the anisotropic NSR of UPDM. Moreover, noise effects were reduced by probability distribution with the 95–99 rule. Significantly, the proposed method effectively represents the anisotropic assessment of the NSR of UPDM.

Characterization of KDP Crystal Surfaces from Single Point Diamond Milling

Potassium Dihydrogen Phosphate (KDP) crystal is widely used in laser frequency multiplications and electro-optical modulators, but its soft-brittle property and thermal sensitive characteristic make it a very difficult-to-machine material. In this paper, an in-house made diamond tool with one tooth is used to face-mill KDP crystal specimens on a high-speed micro CNC machining centre, based on a statistically designed experiment. The morphology and roughness of the milled KDP crystal surfaces are analyzed with respect to the process parameters. It has been found that cutting speed has the largest effect on surface roughness, while axial depth of cut and feed per tooth show a comparable effect on both the Ra and PV roughness measures. From this study, 3 m/s cutting speed, 3 μm axial depth of cut and 1 μm/z feed per tooth are recommended for single point diamond milling of KDP crystal.