J. Eur. Opt. Society-Rapid Publ. 2025, 21, 37 Ó The Author( s), published by EDP Sciences, 2025 https:// doi. org / 10.1051 / jeos / 2025031 Available online at: https:// jeos. edpsciences. org
Journal of the European Optical Society-Rapid Publications
RESEARCH ARTICLE
A new tooling system for corrective finishing of narrow cylindrical optics
Ashwani Pratap 1, 2, 3,*, Chetan Kumar Jain 4, and Anthony Beaucamp 2
1 |
Department of Mechanical Engineering, IIITDM Kurnool, Kurnool 518007, India |
2 |
Department of System Design Engineering, Keio University, Yokohama 223-8521, Japan |
3 |
Zeeko KK, Saitama Shi, Saitama 330-0854, Japan |
4 |
Zeeko Ltd, Vulcan Way, Coalville LE67 3FW, United Kingdom |
Received 25 March 2025 / Accepted 23 June 2025
Abstract. Finishing of complex surfaces needs simultaneous movement of multiple axes and precessing the tool on the surface in a desired tool path. For finishing narrow internal surfaces, the conventional spherical or flat end tools are difficult to precess inside the geometry. Therefore, this work presents a new tooling system for grinding narrow channels on tungsten carbide surface, to be used in optical applications. A thin wheel type finishing wheel and related jig is designed to use on an ultra-precision finishing machine. Finishing using the newly developed wheel type tool with different grade shape adaptive grinding pads could generate excellent surface finish within Ra = 3 nm. Form correction capability of the developed tooling system was also verified where the form error of the channel could be reduced to ~ 7 lm P-V from an initial error of ~ 42 lm P-V, in 5 h of processing time.
Keywords: Finishing, Shape adaptive grinding, Surface roughness, Form correction.
1 Introduction
Cylindrical mirrors find applications in various fields, including laser scanning, laser diode systems, spectrophotometry, and X-ray beam lines [ 1 ]. Grinding or finishing of these surfaces is comparatively difficult by the conventional processes, tooling and machine control software. There are physical contact-based processes and unconventional energy processes for the finishing of optical components, wherein form error and surface roughness could be controlled within tens of nanometer and subnanometer range, respectively [ 2 ]. Unconventional processes such as laser beam finishing suffer with subsurface thermal effects and residual stresses whereas ion beam figuring is limited by its very slow processing [ 3 ]. In the mechanical removal processes, time-dependent removal techniques such as fluid jet finishing( FJP) and shape adaptive grinding( SAG) have been extensively researched and established in last two decades. In fluid jet finishing, pressurized slurry is directed onto the surface in order to polish the surface. Fluid jet finishing has been established to achieve surface roughness less than 10 nm and form error within 100 nm [ 4 ]. The first work on FJP was presented by Fahnle et al. [ 5 ] where they reported that using 10 % SiC abrasives
* Corresponding author: pratap @ iiitk. ac. in
(# 800) in water polishing the surface of a BK7 sample from the roughness 350 nm to 25 nm rms was possible with a low pressure of less than 6 bar. Booij et al. [ 6 ] observedthe linear dependence of material removal rate with slurry concentration. Additionally, it was also observed that the theoretical dependence of material removal rate on parameters in fluid jet polishing includes processing time, abrasive concentration, abrasive diameter, particle velocity, and scanning effect. Fang et al. [ 7 ] reported that the volume removal rate in FJP is approximately proportional to the square root of Young’ s modulus and inversely proportional to the square of the Knoop hardness of glass. Further improvement was observed using ultrasonic cavitationassisted FJP systems that can boost material removal rate by up to 380 % without affecting surface finish, offering advantages for super-fine finishing of optical and prosthetic surfaces [ 8 ]. Recently, surfaces with narrow channels similar to resembling to cylindrical mirrors also showed potential in optical and molding applications which need to be finished to stringent optical matrices [ 9 ]. Fluid jet polishing is a suitable method to process such intricate shaped workpieces. However, performance of FJP is limited when polishing a workpiece having multiple phases with different hardness. One of the examples is tungsten carbide( WC) where cobalt binder present at the grain boundaries is softer as compared to the tungsten carbide grains. In such cases, there are high
This is an Open Access article distributed under the terms of the Creative Commons Attribution License( https:// creativecommons. org / licenses / by / 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.