Shot Peening in the Automotive Industry

in Vol. 21 - March Issue - Year 2020
The Digital Control of Shot Peening

Mario Guagliano

The success of every industrial process depends on the ability to control it and to guarantee that it is performed in a repeatable way with repeatable results. That is to say, that a great mastery and the clear knowledge of the most important process parameters and of how they affect the final result are required. No need to say that also the ability to monitor and to control the process parameters is a priority and a very important task. Since this adds costs, it is necessary to define quantities that can be used and controlled in the production line without increasing time and costs.
The same can be said for shot peening and allied processes. Two are the quantities that were historically developed and universally used to check the quality of shot peening and to guarantee that it is controlled and done with repeatable results: the Almen intensity, and the coverage, and they are universally used still today. By setting these parameters, we are able to control the process and to guarantee that it will give the expected results. No need to underline that these two quantities fit quite well in industrial production since they are affordable and rather fast and do not require expensive tools and instruments to be measured.
But talking with colleagues and industrial engineers, a question is asked more and more frequently: in the digital age, is it still the best way to go to ensure the quality of the process, or it is possible to think and to develop some other procedure, suitable for a digital implementation and for continuously monitoring how the process is performed? This question is of particular interest for mass production, such as automotive-wise, where productivity and quality make the difference and are a priority to remain competitive. And the answer is yes, it is possible if we consider a different management of the process and the necessity to monitor various parameters: the shot flow, which requires specific tools to guarantee a reliable control, the energy transferred to the treated part, related to the media properties as well as to the impact angle, and so on.
Another issue is also how the process parameters affect the quality and the final surface state in terms of roughness and morphology, residual stresses and surface hardening, and guarantee that these remain constant with time.
It is not easy, but the technological facilities to go toward this new process management are at least partially available. That is to say, that high-speed cameras are available, reliable and accurate, fluorescent tracers can be used to check the actual coverage while the new generation XRDs allow rapid measurement of surface residual stresses.
An efficient management of data must be added to these measurements: the use of artificial intelligence is a fundamental step toward shot peening as a fully digitalized process. Traceability of a shot-peened part must be guaranteed by recording process and quality parameters and the development of algorithms able to elaborate these data and to draw the best treatment strategy to close the circle and define the digital twin of shot peening.
Indeed, today, this might appear as a futuristic scenario, but I think we are not so far from reality, and the seeds for an approach like this are already present in many Research and Development departments.
For sure, this step requires considerable investment, but in a short time, it will not be possible to postpone it further, since it will be a need of the factory of the future: it is important to be ready to get on board.

Shot Peening in the Automotive Industry
by Mario Guagliano
Contributing Editor MFN and
Full Professor of Technical University of Milan
20156 Milan, Italy
E-mail: mario@mfn.li

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