Shot peening is a mechanical treatment for metal surfaces, which plays a key role in the automotive industry in increasing the fatigue resistance of the components treated, namely, resistance to mechanical and thermal stress. In recent decades, this technique has been gradually refined, especially in parameter control systems, to ensure consistency and repeatability, in mass production, of the end result. These are two highly important factors when dealing with components used in crucial applications such as engine parts and other parts of vehicles.
The shot peening process was already known in the 1920s and 1930s, at the very outset of contemporary metallurgy. The phenomena of “fatigue” was already observed in the 19th century to study breakages in railway components subjected to long distances with variable loads.
The breakage or micro-breakage of a metal component depends on a surface defect due to the finish or composition of the material. Mechanical and thermal stress create micro-cracks on the surface which, when penetrating deep down, cause breakage. Using shot-peening machines for super surface finishing, a process that eliminates ridges and micro-cracks and makes the surface more uniform, increases the fatigue resistance of metal components used in the automotive industry. Aluminium alloys such as ergal and titanium can also be processed using shot-peening machines.
The cold working treatment can even reach relatively deep depths: the metal surface is hit with a jet of shot at a speed that usually varies from 20 to 120 metres per second. The impact of the shot (usually steel, ceramic or glass) deforms the surface and compacts it. Shot peening is a process that should not be confused with other industrial surface treatments such as sandblasting: the latter cleans and removes surface irregularities, whereas shot-peening machines directly deform the surface.
Thanks to the commitment to research and innovation of manufacturers such as Turbotecnica Engineering, the Italian company with 30 years of experience in the industry, modern shot-peening machines are ideal for application in the aerospace, shipbuilding and automotive industries, allowing metal components to be treated without using harmful chemical products. In the automotive industry in particular, the shot-peening machine has proved to be excellent for processing engine components and other fatigue-sensitive structures, where sudden section changes are involved in the presence of springs, connecting rods, gear wheels and drive shafts. Welded components, which create surface tension, can also benefit from this treatment.