Shot peening, a surface treatment which has become a critical process in many industries due to its ability to improve metal fatigue properties of components of almost any size or geometry and extend the life of critical components that could potentially fail.
Metal fatigue occurs during cyclic loading via tensile stress that has the potential for a crack to start in highly stressed areas. Shot peening mitigates this by imparting a high magnitude, residual compressive stress at the surface in potential failure areas.
When operating in a higher cycle fatigue (lower stress) environment, typical fatigue improvements with shot peening are:
- 3x-10x fatigue life increase
- 10-30% fatigue strength increase
Shot Peening - Process Video
Controlled Shot Peening - Process
Controlled shot peening is a cold working process that uses spherical media known as a shot. As each piece of shot strikes the surface, a dimple is created along with beneficial compressive residual stress. It is a result of localized yielding being restrained by the substrate material (FIGURE 1). If present, prior manufacturing tensile stresses are converted to residual compressive stress. Compressive stress offsets or lowers applied tensile stress. Quite simply, less (tensile) stress equates to longer component life. A typical shot peening stress profile is depicted in (FIGURE 2).
CWST maintains a technical plan of processing instructions for each part number on file. Our facilities store thousands of technical plans for many years. The technical plans take into account – part geometry, masking requirements, base material properties, and review of thin sections to minimize the chance for distortion.
Shot Peening - Industry Specifications
Our facilities are certified to applicable industry approvals including NADCAP, ISO and hundreds of OEM (& Tier 1) certifications including:
- AMS 2430
- AMS 2432
- ABP 1-2028
- MIL-P 81985(AS)
Shot Peening - Benefits
• Prevent Fatigue Failure
Usually related to cyclic loading. Applied tensile stress at the surface is most commonly from bending or torsion. Residual tensile stress induced during manufacturing can also contribute to failure.
• Prevent Metal Fatigue
Improves metal fatigue properties through the use of beneficial compressive stress. This is proven to enhance protection against failures due to:
- Metal fatigue commonly associated with bending or torsional loading
- Stress Corrosion Cracking (SCC)
- Fretting fatigue commonly associated with rotating components
- Contact Fatigue (micro/macro pitting) associated with gear tooth geometry
- Reduction of fatigue scatter from prior manufacturing operations (welding, grinding, anodizing, plating, aggressive machining/grinding, improper thermal exposure)
We can perform on-site shot peening of large components whose sizes exceed shipping limitations or which are installed on their foundations. Our field crews perform on-site shot peening services worldwide to the same quality standards as our processing centers. We utilize certified shot peening techniques to achieve the same level of quality.
Through our on-site capability, we can help customers avoid the logistics and costs of shipping oversized equipment while helping minimize equipment downtime.
Field crews utilize Almen strips, coverage verification & certified peening media to achieve the same high level of quality on-site as they do in-house.
Examples of on-site shot peening projects that CWST Company has performed successfully include:
- Welded fabrications (pressure vessels, crusher bodies, ship hulls, chemical storage tanks, bridges)
- Aircraft component overhaul & repair (wing sections, landing gear, other dynamically loaded components, corrosion removal)
- Power plant components (heat exchanger tubing, turbine casings, rotating components, large fans)
- Plastic pellet transfer facilities for directional peening
- Miscellaneous processing plants (steel mills, paper mills, mining facilities)
Shot peening is performed using shot media, glass, ceramic, or metal balls. Laser peening using laser technology that is digitally applied. To find out whether shot peening or laser peening is right for your application. Learn more
Shot Peening FAQs
Additional Applications of Shot Peening
CWST offers robotic peening to meet the most stringent specifications. Robotic peening offers improved reliability and increased efficiency over previous generations of peening equipment.