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Evaluation of Size and Shape of Shot Peening Media by Image Analysis
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English
Abstract
It is well known that plating and other coatings processes can cause reduction of Fatigue Resistance in metal parts. Shot peening prior to coatings processes will restore most, or all, of the lost fatigue properties. To assure repeatable and reliable results from the shot peening process, the shot must be controlled. The most critical characteristics of peening media are size and shape. Improperly sized shot will give too little, too much or inconsistent layers of compressive stress. Improperly shaped shot may cause surface damage and fatigue properties lower than in the unpeened condition.
For the past forty years, the methods for measurement of shot size and shape have not changed. Shot size is measured by sieve analysis and shape is measured visually by an inspector. These inspection techniques lack speed, accuracy and repeatability and are subject to a significant amount of human error.
This report describes a new method of evaluation that gives improved accuracy, repeatability and speed. Shot peening media can be evaluated simultaneously for both size and shape by image analysis. The results of inspection using an image analyzer are superior to sieve analysis and visual methods. Image Analysis measurements provide much better control of peening media. The time saved in this faster technique can offset the cost of the image analysis system designed for shot evaluation.
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Citation
Gillespie, B. and Fowler, D., "Evaluation of Size and Shape of Shot Peening Media by Image Analysis," SAE Technical Paper 910926, 1991, https://doi.org/10.4271/910926.Also In
References
- Gillespie, B. Kleppe, R.L. “The Use of Shot Peening to Recover Fatigue Strength Debit Due to Finishing/Plating Processes,” SAE Technical Paper 880873 April 1988
- Gillespie, B. “Harmful Effects of Improper Media Control in the Shot Peening Process,” I.I.T.T. International Conference on Shot Peening of Aircraft in Manufacturing Overhaul and Maintenance Los Angeles, CA. November 1990
- Simpson, R.S. Chaisson, G.L. “Quantification of the Effects of Various Levels of Several Critical Shot Peening Process Variables on Workpiece Surface Integrity and the Resultant Effect on Workpiece Fatigue Life,” U.S. Air Force Wright Aeronautical Laboratories Technical Report AFWAL-TR-88-3029
- Dunlap, John “When Machine Vision Meets CIM: A Different Vision,” Advanced Imaging 5 11 November 1990 18 21
- Baxes, G.A. Digital Image Processing, A Practical Primer Prentice-Hall, Inc. N.J. 1984 70 78
- Fowler, D.B. et al. “Inspecting Thermally Sprayed Coatings,” Advanced Materials & Processes 138 November 1990 41 52
- Russ, J.C. Computer Assisted Microscopy, The Measurement and Analysis of Images North Carolina State Univ. 1988
- Joyce-Loebl Image Analysis Principles and Practice Joyce-Loebl Gateshead, England 1985 123 128
- Military Specification Shot Peening of Metal Parts MIL-S-13165C, Sec. 6.11 (a) June 7 1988 11
- Vander Voort, G.F. “Influence of Magnification on Feature Specific Image Analysis Measurements,” Metallography 21 3 August 1988 327 345
- Hewitt, F.C. et al. “Applications of Mathematical Morphology in Imaging,” American Laboratory April 1990
- Vander Voort, G.F. Metallograrhy Principles and Practice McGraw-Hill New York 1984 428 430
- SAE Aerospace Materials Specification “Shot Peening - AMS 2430K,” September 1 1988