Investigation of diamond turning: of rapidly solidified aluminum alloys

Abstract

Aluminum 6061 is often considered the preferred material for manufacturing optical components for ground-based astronomical applications. One reason for using this material is its high specific stiffness and excellent thermal properties. Moreover, a large amount of data exists for this material and commercially available aluminum 6061 can be diamond turned to achieve surface roughness values of approximately 4 to 8 nm, which is adequate for applications that involve the infrared spectral range, but not for the near-ultraviolet wavelength (NUV) spectral range. In this study, we used a novel aluminum material, fabricated using a rapid solidification process that is equivalent to the conventional aluminum 6061 alloy grade. Using rapidly solidified aluminum (RSA) can achieve improved surface finish and enhanced optical performance. The rapid solidification process was realized using a melt spinning operation, which achieves a high cooling rate to yield a fine microstructure. The properties of RSA 6061 are similar to those of conventional aluminum 6061, but its grain size is extremely small. In this paper, the background of RSA is introduced, and the diamond turnability characteristics and coating processes for both traditional aluminum 6061 and RSA are discussed. The surface roughness and grain structure of RSA were evaluated using white light interferometers and the surface roughness during coating of the reflectance multilayers of samples were analyzed using near-ultraviolet wavelengths. Finally, indicators such as optimal cutting parameters and optical performance are discussed.

Artificial Intelligence Monitoring of Hardening Methods and Cutting Conditions and Their Effects on Surface Roughness, Performance, and Finish Turning Costs of Solid-State Recycled Aluminum Alloy 6061 Сhips

“…Islam [31] presented the experimental and the analytical results of an investigation into additional factors that affected the dimensional accuracy and surface roughness, Ra, of turned aluminum 6061, mild steel 1030, and alloy steel 4340 workpieces, as well as the three major cutting parameters-cutting speed, feed rate, and depth of cut. Cheng et al [32,33] discussed diamond turnability characteristics and coating processes for both traditional aluminum 6061 and RSA. Kalyan and Samuel [34] established a set of cutting modes based on the machining forces, surface roughness and chip morphology at varying cutting-edge chamfer widths in the high speed turning of an AlMgSi (Al 6061 T6) alloy, using polycrystalline diamond (PCD) tools.…”

“…Tootooni et al [39] used non-contact, vision-based online measurement for investigating surface finish in the turning of external steel and aluminum-alloy shaft diameters (4340 and 6061 grades). A number of studies [28][29][30][31][32][33][34][35][36][37][38][39] have investigated the turning of 6062 aluminum alloys. However, none accounted for the physical and mechanical properties attributed to the various conditions of the AA6061 workpiece on surface roughness in turning.…”

Optical design and system characterization of an imaging microscope at 121.6 nm

“…Surface microroughness is limited by the diamond turning fabrication process and the substrate material properties. 14,15 The 2-nm specification in Table 2 introduces transmission loss through 4.2% scattering on the primary mirror and 3.8% on the secondary mirror as defined by total integrated scatter (TIS). 17,19 Further analyses for the bidirectional reflectance distribution function (BRDF) of the mirror surface are necessary if the nonspecular angle-dependent reflectance change contributes to the image artifacts.…”

“…13 A diamond turning process is used in fabricating the aluminum mirror substrate, as it offers comparable low-spatial frequency surface quality to the conventional polishing processes. 14,15 It also allows straightforward implementation of freeform optics in the systems. Thus, this work is a test for evaluating direct diamond turning processes for VUV optical systems.…”

Finishing of metal optics by ion beam technologies

“…6 However, by SPDT, a typical roughness of 2-to 3-nm rms is achievable. 1,7,8 An additional issue is the periodic turning marks with a pitch of 1 to 10 μm distance and up to a few ten nanometers in height. As a result, undesired diffraction effects appear in UV/VIS range applications.…”