SHOT PEENING SERVICES
Reasons for Shot Peening
Fatigue failure is 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. CWST’s shot peening services process is a cost effective and practical method of improving metal fatigue properties through the use of beneficial compressive stress. This is proven to enhance protection against failures due to:
- Metal fatigue
- Stress Corrosion Cracking (SCC)
- Contact Fatigue
- Reduction of fatigue scatter from manufacturing processes
Why is Shot Peening so Important?
Shot peening has become a critical process in many industries due to its ability to improve metal fatigue properties and extend the life of critical components that could potentially fail. Metal fatigue occurs when cyclic loading and the associated tensile stress cause a crack to start in a highly stressed area. Shot peening is able to mitigate this by imparting a high magnitude, residual compressive stress at the surface in the potential failure area.
The shot peening compressive stress is opposite the applied tensile stress that causes a crack to start. Parts that have been shot peened are able to survive 3-10 times longer due to the surface being placed in a residual compressive state.
How Shot Peening is Applied
Controlled shot peening is a cold working process which uses spherical media known as shot. Each piece of shot hits the surface and creates an indentation where the surface yields and is restrained by the substrate material. This creates a beneficial compressive residual stress which makes the surface resistant crack initiation and propagation. Prior manufacturing tensile stresses are converted to residual compressive stress
Shot Peening Residual Stress
The residual stress generated by shot peening is of a compressive nature. This compressive stress offsets or lowers applied tensile stress. Quite simply, less (tensile) stress equates to longer part life. A typical shot peening stress profile is depicted in (FIGURE 1).
Shot peening is a practical method of producing surface residual compressive stresses. For applications that require deeper compressive stresses, CWST’s laser peening process imparts a layer of beneficial compressive stress that is up to ten times deeper than that attainable from conventional shot peening.
Control & Quality Considerations for the Shot Peening Process
Each component’s technical plan is generated prior to processing and takes into account: geometry, manufacturing method, base material and potential for distortion.
CWST facilities are capable of meeting most industry standard shot peening specifications, including:
- AMS 2430
- AMS 2432
- ABP 1-2028
- MIL-P 81985(AS)
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 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 oversize equipment, while helping minimize the down time of equipment. Learn More
Related Articles & Brochures
Additional Applications Using the Controlled Shot Peening Process
CWST offers robotic peening to meet the most stringent specifications. Robotic peening offers improved reliability and increased efficiency over previous generations of peening equipment.