A recent and short comparison

The daily business of companies is dictated by manufacturing their product(s) economically and safely. Nowadays, manufacturing processes consider productivity and safety more and more. The two mechanical surface treatment technologies shot peening and deep rolling are used for in similar fields of application. And both technologies are used in main cases to increase the lifetime of components. For the readers of MFN, we will take a short look at these two manufacturing processes: shot peening and deep rolling.

With a focus on accessibility, you can say that shot peening is focused on suitable irregular shapes, but a lot of other applications can also be processed via shot peening. Nevertheless, it is currently also possible to machine (e. g. turbine blades) by deep rolling, which is no longer dependent on the cylindrical form. A lot of free-form shapes or non-cylindrical form shapes can be machined by deep rolling e. g. on a drilling machine. There are also applications which can still only be machined by shot peening, but if you could machine a part by both processes and the focus is on economic aspects, nearly all advantages are on the side of deep rolling:

- The first advantage is the higher depth of penetration of compressive residual stresses caused by higher forces during deep rolling. Furthermore, the residual stresses depend on the rolling force which can easily be adjusted. In comparison to that, shot peening is a complex process with special facilities.
- A further aspect is the coverage, which is adjustable for deep rolling. This process is a reliable and repeatable process which can be monitored. Reasons for this are the limited parameters which can be easily measured by sensors and handled by a monitoring system.
- Another advantage is the speed of this process. It is a fast process in comparison to shot peening. The simplicity of deep rolling means: while you need special and expensive systems for shoot peening, deep rolling is applicable on nearly every turning or milling machine. And here there is the possibility to process the part in one setting after cutting. So there are less non-productive times.
- Another mentioned disadvantage of shot peening is the wide influence range by many parameters: material, shape and size of shot, different types of facilities, the shot angle, the Almen intensity, feed rate and so on.
- A last but important aspect is the produced surface quality: while shot peening worsens the surface of the component and final expensive surface treatments e. g. polishing are necessary, deep rolling improves the surface quality of machined parts.

In the end, both processes have their place and both processes will more often be used within the wide range of manufacturing processes. But nowadays, construction and production managers have to decide more often on which process they should use for their own production. There might be some mentioned aspects that you have not considered before that will help you with future decisions: "shot peening or deep rolling?"

For questions contact: sirko@mfn.li

Trainer Column
by Sirko Fricke,
Official MFN Trainer

More Information at www.mfn.li/trainers