Controlled Shot Peening

How shot peening works

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 which is proven to prevent failures due to:

• Metal fatigue
• Corrosion fatigue
• Stress corrosion cracking
• Intergranular corrosion
• Fretting
• Galling
• Spalling
• Wear

How shot peening is applied

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.

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 processing is carried out using specialist robotic equipment which has been designed in-house, ensuring that the motion of the component to shot flow is consistent.

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.