A Novel Method for Profile Error Analysis of Freeform Surfaces in FTS/STS Diamond Turning

Abstract:

Fast/slow tool servo (FTS/STS) technology plays an important role in machining freeform surfaces for the modern optics industry. The accuracies of these surfaces not only depend on the performance of the FTS/STS but also on the methods of tool path generation (TPG). Current methods of pre-compensating tool nose radius and control dynamics still do not address the inherent profile errors arise from the methods of TPG. Furthermore, it is also not efficient to characterize a freeform surface in the post-machining stage, giving a high risk of failing to meet the accuracy requirements. In this paper, a profile error analysis (PEA) is introduced into the pre-machining stage to address this inherent profile error. PEA is carried out to compare two methods of TPG, namely the constant angle and constant arc methods and optimizes the number of cutting points in the TPG. Thus, the profile accuracy can be pre-determined to meet accuracy requirements by determining the appropriate TPG method with a least number of the cutting points. In the experiments, sinusoidal wave grid and micro-lens array surfaces are fabricated and their profiles successfully achieve the accuracy tolerance of 1 μm. These further credit the capability of PEA as an effective and accurate tool in improving profile accuracies and meeting accuracy requirements.

• Periodical: Key Engineering Materials (Volume 625)
• Pages: 101-107
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.625.101
• Online since: August 2014
• Authors: Wee Keong Neo*, Mark Derek Nadhan, A. Senthil Kumar, Mustafizur Rahman
• Keywords: Fast/Slow Tool Servo, Freeform Surfaces, Optimization, Profile Error Analysis, Ultra-Precision Machining

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