I have recently attended a conference about the methods used to improve the fatigue strength of mechanical elements. Unfortunately, the conference was just virtual, however, it was further confirmation that face-to-face events are much better. Apart from the coffee breaks that we hardly remember, and that I consider the best way to improve your network, the Question & Answers time is also quite different: you need to write your question on the chat board, the chair reads it to the speaker and, if he is attending the session, he will reply without any emphasis. Listening to animated discussions, sometimes even too animated, was much better. I hope we will get back to a normal life and normal events in the near future!

Apart from these comments, the conference was not bad, and I was not surprised to see that shot peening is still the most popular surface treatment for alleviating fatigue and that the so-called “allied processes” are getting more and more attention in many sectors. Indeed, most of them are niche treatments but their peculiar characteristics make them the ideal candidate, in particular and well-defined sectors.

In one of the sessions, one of the questions that was asked was about the possible application of such treatments in the automotive industry, a sector where the production rate is a key factor, but fatigue cannot be neglected in the design stage and the need for light structures is becoming more and more important. 

Why not apply treatments that are commonly used in aeronautics and biomed or in space engineering also in the automotive field, at least in cases where the result could be better than those from shot peening? Why are there not scientific papers describing the application of the allied processes to some mechanical part of a car?

To be sincere, the answer given by the speaker at the conference did not completely convince me. He underlined the fact that in this industry, there are different materials and that it could be a problem to find the right process parameters, but I believe that answers like this mean only “I do not know”, as there are no data available. I think that the main problem is related to the different production rates needed in this field.

While in aeronautics the optimization of the process parameters is one of the major tasks, in the automotive industry the most important aspect is probably avoiding having bottlenecks in the production process. In other words, it is better to use shot peening in such a way that high production rates can be respected rather than maximizing the performance if this means that the production rate is reduced.

And this is even more valid if other niche processes are used. Imagine that different treatments are used for different parts of the car: this adds complexity, time and costs. This is not currently the case and it is better to keep on referring to shot peening if we want to combine improved performances and weight reduction with affordable time and costs. No way to go differently!

However, even in this field there is room for niche cars, such as luxury cars and sports cars. In these cases, performance could be more important than production rate, and these are sectors where the allied processes can be conveniently applied with excellent results. And if it is true that the innovation coming from Formula One is later transferred to mass production, it means that the application of other peening treatments is possibly just a matter of time. Let’s wait and see.

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