Spring fatigue cracks often initiate at the surface. Controlled shot peening aims to create a beneficial compressive residual-stress layer, not simply a rougher appearance.
Why the surface matters
Cyclic tensile stress can grow small surface defects. Residual compression reduces effective surface tension but cannot correct an overstressed design or severe defect.
Parameters need traceability
Media, intensity, coverage, angle, exposure and machine condition affect the result. High-demand projects should define process records and verification.
Process sequence matters
Heat treatment, grinding, plating and peening order changes the final surface. Later material removal or unsuitable processing can reduce the benefit.
Validate through life testing
Need for peening depends on stress, failure mode and cycle target. Compare treated and untreated samples under representative operating conditions.
References
This article is informed by public standards catalogues and industry engineering resources. Project values should be confirmed by drawings, material certificates and sample validation.