Test standards and sample requirements for spring fatigue testing machines in automotive parts quality testing

Test standards and sample requirements for spring fatigue testing machines in automotive parts quality testing

Spring is the most commonly used elastic component in the automobile suspension system. The fatigue life of various springs such as suspension springs, valve springs, clutch springs, and scroll springs directly affects the comfort and safety of the entire vehicle.Spring fatigue testing machineIt is the core equipment for quality inspection of auto parts manufacturing enterprises.This article details the applicable standards, specimen requirements, test methods and selection considerations for spring fatigue testing.

1. Applicable standards for spring fatigue testing

2. Sample requirements

Sample quantity:Each group of conventional fatigue tests requires at least 3-5 specimens, and at least 15 specimens (5 stress levels × 3 repetitions) are required to determine the S-N curve.Factory inspection can be carried out by sampling in accordance with GB/T 16947.

Sample status:The sample should be in the final heat treatment state, and the spring after surface shot peening should be tested 24 hours after shot peening to avoid residual stress relaxation affecting the results.The grinding surface at the end of the spring must be perpendicular to the axis, and the end face runout should be ≤0.5mm.

Workwear requirements:The upper and lower support plates of the spring need to fit the end face of the spring. The hardness of the support plate is ≥HRC55 and the surface flatness is ≤0.02mm.For springs with different properties (such as variable pitch and variable diameter), special support tooling needs to be designed to ensure uniform force.

3. Testing methods and evaluation indicators

Constant amplitude fatigue test:Set the maximum spring force Fmax and the minimum spring force Fmin (usually 10%-30% of Fmax), frequency 5-20Hz, cycle until fracture or reach the specified life (usually 10⁶-10⁷ times).Record the number of fracture cycles.

Stiffness decay monitoring:The test is paused every 1,000 cycles to measure changes in spring stiffness.GB/T 16947 stipulates that fatigue failure is determined when the stiffness decreases by more than 10% or the free height decreases by more than 5%.

Spiral spring test (new hot spot in 2026):Popular Douyin content in 2026 shows that scroll spring fatigue testing machines have become a new demand point.The scroll spring needs to test the torque-angle relationship, torque attenuation rate, and breaking torque. The test speed and angle are adjustable.

4. Things to note when selecting a spring fatigue testing machine

1. Load and travel range:Select according to the maximum working load and working stroke of the spring.Suspension springs are usually 5-50kN, and valve springs are 1-5kN.The stroke needs to be more than 20% greater than the maximum deformation of the spring.

2. Test frequency:The higher the frequency of spring testing, the shorter the test cycle.The electronic servo drive can reach more than 20Hz, and the electro-hydraulic servo drive is suitable for large load springs but has a low frequency (usually ≤5Hz).The top picks for 2026 areHigh frequency electronic servo spring fatigue testing machine, taking into account both frequency and accuracy.

3. Multi-station efficiency:Mass production companies recommend choosing a 4-6 station multi-station spring fatigue testing machine to test multiple pieces at one time and increase the efficiency by 4-6 times.Independent control and independent counting between workstations are key.

4. Real-time monitoring of stiffness:Mid- to high-end equipment should have the function of automatically measuring stiffness every 1,000 times without shutting down.This is the core indicator that distinguishes ordinary spring testing machines from professional fatigue testing machines.

5. Automatic shutdown when broken:If the force value suddenly changes after the spring breaks, the equipment should be identified and shut down within one cycle to protect the equipment and sample fragments.

Shandong Huayan Intelligent Equipment GroupWe provide a full range of spring fatigue testing machines, including single-station/multi-station compression spring fatigue machines, valve spring high-frequency fatigue machines, scroll spring torsion fatigue machines, and air spring fatigue testing machines.The equipment supports GB/T 1239, GB/T 23935, QC/T 1037 and other standards, with real-time stiffness monitoring and automatic shutdown when fracture occurs, and has served hundreds of auto parts companies.As a source manufacturer of mechanical testing instruments, we welcome samples for testing.

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