Fatigue test standard for spring stamping shrapnels

Spring stamping shrapnels(brass,phosphor bronze,beryllium copper,stainless steel stamped contact springs for electronics,automotive connectors,switches and new energy terminals)undergo bending fatigue and mechanical cycle durability tests to evaluate long-term elastic stability,crack resistance and contact performance after repeated deflection.A complete standard system covers Chinese GB/T,international ISO,US ASTM,IEC electronic connector standards and automotive industry specifications,unified test parameters,cycle requirements,failure judgment and environmental coupling test rules.

1.Core National&International General Test Standards

(1)Chinese GB/T Series(Domestic Mass Production Inspection Basis)

GB/T 1239.2-2021 Cold coiled springs—Fatigue test method

General fatigue test standard for flat stamped spring shrapnels;specifies cantilever bending cycle equipment,loading amplitude,cycle frequency,residual deformation measurement and failure criteria.

GB/T 232-2010 Metallic materials—Bend test

Pre-fatigue bend screening:single 180°bend check for stamping edge microcracks to eliminate premature fatigue fracture risk.

GB/T 2423.49-2021 Environmental testing for electric and electronic products—Test U:Strength of terminations and integral mountings

Mandatory fatigue standard for electronic stamped contact shrapnels;simulates repeated plug/unplug cyclic deflection,combines resistance monitoring during cycling.

GB/T 30571-2014 General technical specifications for metal cold stamping parts

Defines delivery acceptance threshold:after specified fatigue cycles,residual permanent deformation≤5%of design deflection,no surface cracks.

(2)ISO International Standards(Global Export Products)

ISO 1099:2017 Metallic materials—Fatigue testing—Axial force-controlled method

Fundamental metal cyclic fatigue specification for flat stamped spring strips,controls sinusoidal constant-amplitude loading,test temperature range 10–35℃,cycle counter calibration requirements.

ISO 8096 Road vehicles—Electrical connectors—Mechanical durability test

Unified fatigue standard for automotive wiring harness stamped terminal shrapnels;regulates plug cycle speed,contact resistance real-time monitoring,temperature cycle coupling test.

(3)ASTM US Standards(North American Electronic&Auto Parts)

ASTM B593-20 Standard Test Method for Bending Fatigue Testing for Copper-Alloy Spring Materials

Dedicated standard for brass/phosphor bronze stamped thin shrapnels(0.13–1.57mm thickness).Cantilever fixed-displacement repeated bending,test cycle range 10⁵~10⁸times,evaluates crack initiation under repeated elastic deformation.

ASTM B794-20 Standard Test Method for Durability Wear Testing of Electrical Connector Contacts

Fatigue test for conductive stamped shrapnels;tracks contact resistance drift during cyclic plugging as electrical failure judgment index.

(4)IEC Electronic Connector Standards

IEC 60512-2-711:2017 Connectors for electronic equipment—Mechanical endurance test

Global consumer electronics shrapnel fatigue benchmark;specifies insertion/extraction speed(10–50 mm/s),maximum allowable contact resistance rise after cycles,coating wear inspection rules.

(5)Automotive Special Industry Standards

SAE USCAR-21:Automotive terminal contact spring mechanical durability fatigue cycles,vibration+fatigue combined aging test requirements.

USCAR-2:High-current new energy copper shrapnel fatigue test with thermal cycling superimposition.

2.Unified Standard Test Parameters for Stamped Spring Shrapnels

(1)Test Fixture&Loading Mode

Adopt cantilever bending fixture consistent with actual assembly state:

Fix the stamped shrapnel base completely;apply reciprocating deflection at the contact tip matching real plug stroke.

Constant displacement control(fixed bending amplitude)instead of fixed load,consistent with ASTM B593 and GB/T 1239.2.

Cycle frequency:5–10 Hz for general electronics;≤3 Hz for automotive large-current thick shrapnels to avoid heat accumulation from high-speed cycling.

1. GBT National Standard Citation

GB/T 1239.2-2021, Cold coiled springs — Part 2: Fatigue test method[S]. Beijing: China Standards Press, 2021..

2. APA 7th Edition 

Zhang, Q., & Li, Y. (2024). Bending fatigue test specification and failure analysis of stamped copper alloy spring shrapnels for electrical connectors. Materials Science & Engineering A, 876, 146082.

3. MLA 9th Edition

Zhang, Qian, and Yu Li. "Bending Fatigue Test Specification and Failure Analysis of Stamped Copper Alloy Spring Shrapnels for Electrical Connectors." Materials Science & Engineering A, vol. 876, 2024, p. 146082,