Shot peening

Definition

Shot peening is a mechanical surface treatment process that involves bombarding a material's surface with small spherical media, known as shot, to induce compressive residual stresses and improve fatigue resistance. This technique enhances the material's surface properties, making it crucial in applications where components like bearings and gears are subjected to cyclic loading, thereby extending their lifespan and performance.

5 Must Know Facts For Your Next Test

1. Shot peening can effectively reduce the risk of fatigue failure in components by inducing compressive residual stresses on the surface, counteracting tensile stresses during operation.
2. The size and type of shot used in shot peening can be tailored based on the specific material and desired surface characteristics, impacting the effectiveness of the treatment.
3. This process not only enhances fatigue resistance but also improves wear resistance and can help prevent stress corrosion cracking in certain environments.
4. The intensity of shot peening is measured in terms of coverage, which refers to how uniformly the surface is treated, ensuring maximum benefits from the process.
5. Properly executed shot peening can lead to an increase in service life for components such as gears and bearings, ultimately leading to cost savings through reduced maintenance and replacement.

Review Questions

• How does shot peening improve the performance and lifespan of components subjected to cyclic loading?
  • Shot peening improves the performance and lifespan of components like gears and bearings by introducing compressive residual stresses on their surfaces. This counteracts tensile stresses that occur during cyclic loading, thereby reducing the likelihood of fatigue failures. As a result, components treated with shot peening exhibit enhanced fatigue strength and overall durability, allowing them to withstand repeated stress over time.
• What factors influence the effectiveness of shot peening on different materials and how might these factors vary in applications involving bearings versus gears?
  • The effectiveness of shot peening is influenced by factors such as the size, type, and hardness of the shot used, as well as the intensity and duration of the treatment. In applications involving bearings, which typically experience rolling contact fatigue, shot peening must be carefully calibrated to enhance surface properties without altering dimensional tolerances. Conversely, for gears that endure both bending and contact stresses, varying shot parameters may be needed to optimize resistance against both wear and fatigue failures.
• Evaluate the long-term benefits of implementing shot peening in manufacturing processes for critical mechanical components versus traditional surface treatments.
  • Implementing shot peening in manufacturing processes for critical mechanical components offers significant long-term benefits compared to traditional surface treatments. While conventional methods may enhance surface hardness or smoothness, shot peening specifically targets fatigue resistance by inducing beneficial compressive residual stresses. This leads to reduced failure rates and increased service life for components like bearings and gears under cyclic loads. Additionally, the cost savings from fewer replacements and less downtime due to maintenance highlight the economic advantages of adopting shot peening as a preferred surface treatment method.

Related terms

Residual Stress: Internal forces locked within a material that can influence its strength and fatigue properties, often introduced through processes like shot peening.

Fatigue Strength: The maximum stress a material can withstand for a specified number of cycles without failing, significantly improved by processes such as shot peening.

Surface Hardening:

A process used to increase the hardness of the surface of a material, which can be achieved through various methods including shot peening.