Effective Use of Fluorescent Tracers for Peening Coverage

Author:  Peter Bailey, Electronics Inc., Cincinnati, OH, US
Source:  Conf Proc: ICSP-8 Sept. 16-20, 2002 Garmisch-Partenkirchen, Germany
Doc ID:  2002014
Year of Publication:  2002
Abstract:  
Abstract Fluorescent tracers for determining shot peening coverage have been in use for several decades. Their most appropriate applications are nozzle targeting and detection of coverage in difficult to peen areas. To determine actual percent coverage more sophisticated techniques are required. Frequently, tracers are not used properly or effectively. The most common misuse is to assume that full coverage always requires complete tracer removal. In fact, supplier instructions warn against this assumption and recommend the use of a standard on which tracer removal is compared with magnified visual determination of coverage. Tracer misuse often results in over-coverage by continuing peening well past full coverage until all tracer is removed. Under-coverage is also possible where excessive small or abrasive media prematurely removes the tracer. Neither is good for fatigue protection. This paper describes the removal behavior of fluorescent tracers under a range of peening media and process conditions and part material hardness. Analysis of the data suggests methods that make 100% coverage more easily determinable by tracers. The purpose of the study was to increase the effectiveness of using fluorescent tracers and also their credibility. The author believes that if they are used with knowledge and common sense, improved production efficiency will result and over-peening will be minimized.