Shot Peening

Surface compression.
Fatigue life 2–5× better.
AMS 2430.

Shot peening creates beneficial compressive residual stress in the surface layer of metal parts by bombarding the surface with small hardened beads. Dramatically improves fatigue life — standard for aerospace springs, landing gear, compressor blades, and fatigue-critical components.

Shot Peening Quote Aerospace CNC

AMS 2430 2–5× fatigue life Almen verified Aerospace qualified

01 · What it is

How Shot Peening works.

Shot peening is a cold-working process that bombards a metal surface with small hardened steel, ceramic, or glass beads at high velocity (50–100 m/s). Each bead impact plastically deforms a small area of the surface, creating a thin layer of compressive residual stress. Because fatigue cracks initiate at surface tensile stresses, this compressive surface layer dramatically increases fatigue life — typically 2–5× improvement.

The process is fundamentally different from shot blasting: shot blasting cleans and roughens the surface (high-velocity coarse shot), while shot peening creates controlled residual stress with specific Almen intensity measurement. Shot peening is a specified engineering process with documented parameters — shot size, velocity, coverage, Almen intensity — not just surface cleaning.

Aerospace specification AMS 2430 governs shot peening for aerospace components. Each batch is process-verified using Almen test strips measuring peening intensity. Documented records traceable to specification are standard for aerospace Tier-2/3 suppliers.

02 · Specifications

Capability specs.

AMS 2430

Aerospace standard

Standard specification for shot peening aerospace components

2–5×

Fatigue life improvement

Typical improvement in fatigue life for peened vs unpeened components

0.1–0.5 mm

Compressive layer depth

Depth of beneficial residual stress depending on Almen intensity

Almen A0.004–A0.020

Intensity range

Almen intensity measured on "A" strips. Higher = deeper residual stress

200% coverage

Full coverage

Standard target — surface completely peened with 2× overlap

S110 to S330

Shot sizes

Steel shot sizes from small (0.3 mm) to large (0.8 mm)

Ceramic or glass

Alt media

Ceramic beads for aluminum (no iron contamination), glass for delicate

Steel / Al / Ti

Material compatibility

All metal alloys. Different shot media selected per material

03 · Applications

Where Shot Peening excels.

Aerospace springs

Coil springs, leaf springs — fatigue life improvement critical for safety

Landing gear components

High-cycle fatigue aerospace parts — peening required per AMS 2430

Compressor & turbine blades

Jet engine blades — fatigue life + cleaning

Gears

Transmission gears, differential gears — peened tooth flanks for fatigue life

Automotive springs

Coil springs, leaf springs for automotive — peening standard practice

Aircraft structural

Aircraft structural hardware — fatigue improvement for flight-critical parts

Firearm components

Gun components, springs, slides — extended service life

Helicopter rotor

Helicopter rotor components — high-cycle fatigue critical

Torsion bars

Automotive and industrial torsion bars — peened for fatigue resistance

04 · When not to use it

Not suitable for:

Every process has its limits. Being honest about where Shot Peening isn\'t the right answer saves time and money.

Parts where surface texture matters (cosmetic parts) — peening leaves dimpled texture
Parts where tight tolerances already achieved — peening alters surface dimensions slightly
Very thin material — peening intensity can cause warping on thin sections
Soft materials (annealed aluminum, copper) — compressive layer benefit minimal
Parts not subject to fatigue loading — no benefit, wasted process cost

FAQ

Shot Peening questions.

Fatigue cracks initiate at surface tensile stresses. When cyclic loading creates a surface tensile stress, a crack can start. Peening creates a compressive layer at the surface — before cyclic loading creates tensile stress, the surface is already in compression. Fatigue cracks cannot initiate until the compressive preload is overcome. Effect: 2–5× fatigue life improvement depending on part geometry and loading.

Almen intensity measures peening effect via a standardized test strip. An Almen strip is thin hardened steel that bends measurably when peened (the strip curves because peened side has compressive stress). Strip curvature measured on Almen gauge. Designations: A-strip for standard intensity (0.004–0.020 range), C-strip for higher intensity, N-strip for lower. Example spec: "Peen per AMS 2430 to Almen intensity 0.010–0.015 A, 200% coverage."

Shot blasting: surface cleaning, removes scale/rust, uses coarse media at high velocity, leaves rough texture. No engineering purpose beyond cleaning. Shot peening: controlled process with specific shot size, velocity, coverage, and Almen intensity. Engineering purpose: residual stress management for fatigue life. Same basic equipment but dramatically different process control and engineering intent.

Minimally. Peening may cause 0.005–0.05 mm growth on the peened surface due to plastic deformation. For precision parts, this should be accounted for in the machining sequence: peen first, then finish-machine critical surfaces if tight tolerance required. For parts where ±0.05 mm dimensional change is acceptable, peening doesn't compromise fit.

Shot peening cost: $10–40 per part for small parts, up to $100+ for large complex peening. Significant cost adder, but usually justified by fatigue life improvement. For safety-critical aerospace: peening is mandatory per specification — not optional. For commercial applications where fatigue isn't limiting, peening may be overkill. Cost-benefit analysis typically favors peening for any fatigue-loaded part.

Shot peening typically adds 3–7 business days to overall lead time. Specific peening services routed through our AMS 2430-qualified partner for aerospace work. Documentation package (shot media records, Almen strip results, traceability) included. For non-aerospace peening (general automotive, industrial), in-house peening with standard documentation.