Mechanical polishing of fan blade by a prototype random-orbital tool

The main objective of this study is to better understand the influence of water and air coolant-induced surface texturing and its characterization by a new random-orbital polishing method and prototype tool. Mechanical polishing is the most common process to remove surface irregularities on fa...

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Main Author: Danaraj, Edgar Jeevan
Other Authors: Yeo Swee Hock
Format: Thesis-Master by Research
Language:English
Published: Nanyang Technological University 2022
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Online Access:https://hdl.handle.net/10356/154926
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spelling sg-ntu-dr.10356-1549262023-03-11T18:04:52Z Mechanical polishing of fan blade by a prototype random-orbital tool Danaraj, Edgar Jeevan Yeo Swee Hock School of Mechanical and Aerospace Engineering MSHYEO@ntu.edu.sg Engineering::Mechanical engineering Engineering::Manufacturing The main objective of this study is to better understand the influence of water and air coolant-induced surface texturing and its characterization by a new random-orbital polishing method and prototype tool. Mechanical polishing is the most common process to remove surface irregularities on fan blades such as scallop height features, while maintaining the required dimensional limits and textures. After the polishing process, the part will undergo shot peening, vibratory finishing and later, painting and coating at the final stages. It is therefore essential for the fan blade surface to pre-treated with appropriate surface conditions to promote good surface-to-surface adhesion at the end of the manufacturing cycle. The existing method uses a single-axis rotary polishing tool where an external water coolant source is performed ad-hoc. This polishing method can produce average surface roughness, Ra, of 1.0 µm that satisfies the requirement. However, this form is aggressive and has a high material removal rate, resulting in excessive reduction in material thickness, thus warrants rejection of costly fan blade. The criteria require surface roughness, Ra, between 0.8 to 1.0 µm and maximum height profile Rz, between 5.0 to 6.0 µm for post-polishing condition, while maintaining low material removal rate to prevent under-thickness of the fan blade. Experimental trials were performed on fan blade specimens at the leading-edge sections and its surface topography characterized by coherence correlation interferometry. A range of different abrasive grit sizes was tested for suitability of media selection. Integrating in-line cooled air with deionized water to the process achieved desirable surface roughness, Ra, of 0.8 µm and height profile Rz, of 5.8 µm, while simultaneously removing all traces of scallop height features and maintaining the leading-edge thickness within tolerance. Taking into consideration that the surface texture measurements are random in nature, the corresponding polishing methods were also analyzed with statistical functions by fast Fourier transform (FFT) and power spectral density (PSD). Comparison between the surface texture parameters or statistical functions with the corresponding polishing methods, were then established. The surface integrity of the polished fan blade and wear condition of the abrasive disk are also reported in this study. Master of Engineering 2022-01-17T00:25:33Z 2022-01-17T00:25:33Z 2021 Thesis-Master by Research Danaraj, E. J. (2021). Mechanical polishing of fan blade by a prototype random-orbital tool. Master's thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/154926 https://hdl.handle.net/10356/154926 10.32657/10356/154926 en This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0). application/pdf Nanyang Technological University
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Mechanical engineering
Engineering::Manufacturing
spellingShingle Engineering::Mechanical engineering
Engineering::Manufacturing
Danaraj, Edgar Jeevan
Mechanical polishing of fan blade by a prototype random-orbital tool
description The main objective of this study is to better understand the influence of water and air coolant-induced surface texturing and its characterization by a new random-orbital polishing method and prototype tool. Mechanical polishing is the most common process to remove surface irregularities on fan blades such as scallop height features, while maintaining the required dimensional limits and textures. After the polishing process, the part will undergo shot peening, vibratory finishing and later, painting and coating at the final stages. It is therefore essential for the fan blade surface to pre-treated with appropriate surface conditions to promote good surface-to-surface adhesion at the end of the manufacturing cycle. The existing method uses a single-axis rotary polishing tool where an external water coolant source is performed ad-hoc. This polishing method can produce average surface roughness, Ra, of 1.0 µm that satisfies the requirement. However, this form is aggressive and has a high material removal rate, resulting in excessive reduction in material thickness, thus warrants rejection of costly fan blade. The criteria require surface roughness, Ra, between 0.8 to 1.0 µm and maximum height profile Rz, between 5.0 to 6.0 µm for post-polishing condition, while maintaining low material removal rate to prevent under-thickness of the fan blade. Experimental trials were performed on fan blade specimens at the leading-edge sections and its surface topography characterized by coherence correlation interferometry. A range of different abrasive grit sizes was tested for suitability of media selection. Integrating in-line cooled air with deionized water to the process achieved desirable surface roughness, Ra, of 0.8 µm and height profile Rz, of 5.8 µm, while simultaneously removing all traces of scallop height features and maintaining the leading-edge thickness within tolerance. Taking into consideration that the surface texture measurements are random in nature, the corresponding polishing methods were also analyzed with statistical functions by fast Fourier transform (FFT) and power spectral density (PSD). Comparison between the surface texture parameters or statistical functions with the corresponding polishing methods, were then established. The surface integrity of the polished fan blade and wear condition of the abrasive disk are also reported in this study.
author2 Yeo Swee Hock
author_facet Yeo Swee Hock
Danaraj, Edgar Jeevan
format Thesis-Master by Research
author Danaraj, Edgar Jeevan
author_sort Danaraj, Edgar Jeevan
title Mechanical polishing of fan blade by a prototype random-orbital tool
title_short Mechanical polishing of fan blade by a prototype random-orbital tool
title_full Mechanical polishing of fan blade by a prototype random-orbital tool
title_fullStr Mechanical polishing of fan blade by a prototype random-orbital tool
title_full_unstemmed Mechanical polishing of fan blade by a prototype random-orbital tool
title_sort mechanical polishing of fan blade by a prototype random-orbital tool
publisher Nanyang Technological University
publishDate 2022
url https://hdl.handle.net/10356/154926
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