What Does “Shot Peening” Do & How It Increases Strength In Metals

How Does The Process of Shot Peening Work?

Shot peening is a process invented in the 1930s specifically to increase the fatigue strength of various metal components that encounter high levels of alternating stress on a regular basis (i.e., motorcycle engines and chains). In other words, it makes shot peened parts on your bike stronger and last for much longer than they usually would. Below you’ll find a brief synopsis of shot peening and what it entails: from the process of shot peening to its most important benefits.

Shot Peening Gear

The majority of shot peening is performed using what is called air blasters (also called shot blasters). These air blasters “blast” tiny spherical media (more on media in just a minute) at very high speeds using high-pressure air. When the media makes contact with the surface it is blasting; a small indentation is created in the metal from the impact.

There are several different types of media that can be used to shot peen a component. The media used during the process is chosen based on the type of component that is being shot peened. For instance, when shot peening components found inside of an engine, you would want to use either walnut hull or cherry pit abrasive and avoid using media such as sand or glass beads, due to the risk of damaging the engine.

Other media used in shot peening include ceramic beads, steel shot, and rounded cut wire.

Related: Serious Problems With Running Ethanol Blended Gas In Your 2-Stroke Dirt Bike

How Does Shot Peening Make Components Stronger?

When the media strikes the component, it creates a small divot in the surface of the metal. The moment that divot is formed it changes the mechanical properties of the component’s surface.

Before the component is peened, its surface contains a high level of tensile stress. This is a significant cause of stress fractures and fatigue cracks in metal components. When the shot peen is performed, each particle of the media being used generates compressive stress.

Shot Peened Chains

These compressive stresses overlap each other on the surface of the component, eventually covering the entire area of the surface, thus negating the tensile stress that was previously on the surface, making the part much more resistant to stress cracks and fractures.

Two Other Major Benefits of Shot Peening

We’ve already established that increasing the component’s resistance to stress fractures and cracks is one of the most significant benefits to shot peening, but that’s not the only benefit this process possesses:

Shot peening also greatly reduces the components’ susceptibility to corrosion and cracking, as well as increases the overall oil retention and lubricity of engine components.
By now you should have a decent understanding of what shot peening is, how it works, and why it makes components stronger. It’s an invaluable process for prolonging the life of specific parts on your bike.

You can either purchase parts that are already shot peened, or you can shot peen the parts yourself. However, if you’re planning to attempt shot peening on your own, please consult a professional first. It is easy to flub it up if it’s your first try.

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