Shot Peening

Component failure is often related to residual tensile stress induced during manufacture and certain operating conditions. The controlled shot peening process is a cost effective and practical method of replacing tensile stress with beneficial compressive stress. This is proven to enhance protection against failures due to:

  • Metal fatigue
  • Stress Corrosion Cracking (SCC)
  • Exfoliation corrosion
  • Fretting
  • Galling
  • Spalling
  • Wear

Process
Controlled shot peening is a cold working process applied using spherical media known as shot.  As each piece of shot hits the surface it creates an indentation where the surface will attempt to yield but is restrained by the substrate material.  This conflict causes the substrate material to compress creating a beneficial compressive residual stress which makes the surface resistant to crack initiation and propagation and in the process removes any prior manufacturing tensile stresses.

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Video showing the shot peening process

 

Shot peening  is the most economical and practical method of ensuring surface residual compressive stresses. For applications that require deeper residual compressive stresses than those provided by shot peening, CWST’s laser peening process imparts a layer of beneficial compressive stress that is four times deeper than that attainable from conventional shot peening  treatments.

Onsite Shot Peening
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 almen strips, proper coverage and certified peening media to achieve the same high level of quality in our on-site shot peening projects.

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 this equipment. Learn more

Control and quality considerations for the shot peening process

Each application is specified prior to processing which takes into account: geometry, manufacturing method, base material, strain sensitivity, in-service environment and loading conditions, as well as costs and turnaround time.

When these parameters have been established, the required depth of compressive layer, choice and size of media, intensity and coverage and required surface stress will be calculated and tested, ensuring that any repeat work is carried out to the same specification as the original application.

The majority of our controlled shot peening services are carried out using specialist robotic equipment which has been designed in-house, ensuring that the motion of the component to shot flow is consistent.

CWST facilities are capable of meeting most industry standard shot peening specifications, including:

    • AMS-S-13165
    • BAC-5730
    • PWA-6
    • RPS-428
    • AMS 2430
    • AMS 2432
    • J2441
    • MIL-S-13165C
    • ABP 1-2028
    • MIL-P 81985(AS)
    • MIL-STD-852
    • P11TF3

Additional applications using the controlled shot peening process

Shot Peen Forming – Controlled shot peening can also change the shape of a component i.e. form the curvature in wing skins and increasing resistance to flexural bending fatigue

Correction of Distortion – Distortion caused during manufacturing can alter the stress pattern of the final machined part, increasing the risk of stress corrosion cracking and fatigue. This can be corrected with controlled shot peening.

C.A.S.E. Isotropic Superfinishing – In combination with a chemical assisted process, the surface can be smoothed to a mirror like finish which retains valleys for lubrication. Ideal for components in metal to metal contact like gears and transmissions.

Peentex Surface Texturing – Surface textures offering protection for architectural applications such as cladding and signage and non-slip finishes for tooling. This process can also create mirror like surfaces for decorative purposes.

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