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Electropolishing a space age process

Electropolishing a space age process Electropolishing: a space age process John Swain Electropolishing or, to give it its more metal surface through eloctropolishing. Inspection aid precise title, electrochemical polishing, A wide range of metals can be Electropolishing can also be used as a has now become an accepted finishing electropolished, including aluminium, valuable inspection aid. The removal aid in the aerospace industry. Few copper alloys and carbon steels, but the of a surface layer on castings, for processes offer the highly advan­ process has found its commercial example, for under-carriage com­ tageous technical characteristics success mainly in the treatment of ponents, can reveal cracks, inclusions achieved by a treatment once stainless steel and high nickel-alloys. and other material defects. A derogatively referred to as "reverse The photograph shows an aerospace judgement can then be made as to plating". stainless steel casting produced by the whether to proceed with costly Certainly, the action of electro­ lost wax method and electropolished machining operations or reject the plating is reversed in so far as nothing by Anopol. The as-cast outer skin has casting at this early stage. been electrochemically eroded away to is deposited on the surface of a Turbine blades are also electro­ reveal the metal in its true condition. component; quite the contrary, some­ polished, not only as an aid to thing is removed. The outer surface The resulting component is not only inspection but also to remove fine layer is removed in a very specific exceptionally clean, but also easy to surface irregularities which could manner; high spots and edges are maintain in such a state owing to the result in fatigue failure in service. The micro-smooth surface texture. In eroded preferentially and the resulting action of removing an outer metal layer addition, corrosion resistance is greatly surface is both micro-smooth and, electrochemically produces no thermal equally importantly, free of enhanced and the removal of the distortion and there is no danger of contaminants resulting from previous tenacious outer skin benefits sub­ hydrogen embrittlement occurring. heat or mechanical treatments. sequent drilling and machining Obtaining the best possible results operations. No passivation processing Figure 1 uses schematic diagrams to from electropolishing is dependent on is necessary since electropolishing illustrate progressive levelling of a a number of factors. The polishing leaves a passive oxide layer on the solution or electrolyte employed will component's surface, essential for play a role but, more importantly, the maximum corrosion resistance. method of jigging and the application of the correct current will ultimately determine the final finishing. For these reasons, high-integrity components should only be entrusted to electro­ polishing companies possessing the correct equipment and expertise. Electropolishing, carried out by experienced personnel, is recognized as a reliable and valuable tool in the aerospace industries for treating components subject to stringent demands. No other process produces microsmooth, clean and stress-free surfaces on parts of unlimited complexity. John Swain is Managing Director at Anopol Ltd, 70 Bordesley Street, Birmingham B5 5QJ. Tel: 0121 632 6888: Fax: 0121 631 2274. Aircraft Engineering and Aerospace Technology, Vol. 67 No. 3, 1995, p . 9, © MCB University Press, 0002-2667 AEAT May/June, 1995 9 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

Electropolishing a space age process

Aircraft Engineering and Aerospace Technology , Volume 67 (3): 1 – Mar 1, 1995

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb037564
Publisher site
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Abstract

Electropolishing: a space age process John Swain Electropolishing or, to give it its more metal surface through eloctropolishing. Inspection aid precise title, electrochemical polishing, A wide range of metals can be Electropolishing can also be used as a has now become an accepted finishing electropolished, including aluminium, valuable inspection aid. The removal aid in the aerospace industry. Few copper alloys and carbon steels, but the of a surface layer on castings, for processes offer the highly advan­ process has found its commercial example, for under-carriage com­ tageous technical characteristics success mainly in the treatment of ponents, can reveal cracks, inclusions achieved by a treatment once stainless steel and high nickel-alloys. and other material defects. A derogatively referred to as "reverse The photograph shows an aerospace judgement can then be made as to plating". stainless steel casting produced by the whether to proceed with costly Certainly, the action of electro­ lost wax method and electropolished machining operations or reject the plating is reversed in so far as nothing by Anopol. The as-cast outer skin has casting at this early stage. been electrochemically eroded away to is deposited on the surface of a Turbine blades are also electro­ reveal the metal in its true condition. component; quite the contrary, some­ polished, not only as an aid to thing is removed. The outer surface The resulting component is not only inspection but also to remove fine layer is removed in a very specific exceptionally clean, but also easy to surface irregularities which could manner; high spots and edges are maintain in such a state owing to the result in fatigue failure in service. The micro-smooth surface texture. In eroded preferentially and the resulting action of removing an outer metal layer addition, corrosion resistance is greatly surface is both micro-smooth and, electrochemically produces no thermal equally importantly, free of enhanced and the removal of the distortion and there is no danger of contaminants resulting from previous tenacious outer skin benefits sub­ hydrogen embrittlement occurring. heat or mechanical treatments. sequent drilling and machining Obtaining the best possible results operations. No passivation processing Figure 1 uses schematic diagrams to from electropolishing is dependent on is necessary since electropolishing illustrate progressive levelling of a a number of factors. The polishing leaves a passive oxide layer on the solution or electrolyte employed will component's surface, essential for play a role but, more importantly, the maximum corrosion resistance. method of jigging and the application of the correct current will ultimately determine the final finishing. For these reasons, high-integrity components should only be entrusted to electro­ polishing companies possessing the correct equipment and expertise. Electropolishing, carried out by experienced personnel, is recognized as a reliable and valuable tool in the aerospace industries for treating components subject to stringent demands. No other process produces microsmooth, clean and stress-free surfaces on parts of unlimited complexity. John Swain is Managing Director at Anopol Ltd, 70 Bordesley Street, Birmingham B5 5QJ. Tel: 0121 632 6888: Fax: 0121 631 2274. Aircraft Engineering and Aerospace Technology, Vol. 67 No. 3, 1995, p . 9, © MCB University Press, 0002-2667 AEAT May/June, 1995 9

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Mar 1, 1995

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