Surface Inspection of Valve Spring Wire with Special Geometries
Surface defects in valve spring wire can cause spring failure and engine damage. Eddy current testing reliably detects defects, even on special geometries.
The challenge
Valve spring wire is safety-critical in automotive engines, as surface defects can cause spring failure and engine damage. Increasing performance requirements demand high-quality material. Modern valve spring wires feature special geometries such as oval, egg or lemon shapes. These non-circular profiles create varying distances between the wire surface and the sensor, posing significant challenges for reliable and sensitive surface inspection.
The solution
FOERSTER applies eddy current testing using CIRCOGRAPH combined with a DEFECTOMAT channel to inspect valve spring wire with special geometries. Rotating CIRCOGRAPH probes detect longitudinal defects, while DEFECTOMAT identifies transverse and point defects. A dedicated calibration process compensates for geometry-related distance variations, ensuring stable signal evaluation. Customer-specific through-type coils further enhance sensitivity.
The result
The solution enables reliable detection of surface defects from depths as low as 70 µm, despite varying sensor distances. Distance compensation and adapted coil design ensure high detection probability for longitudinal, transverse and point defects. Automated, non-destructive testing guarantees consistent product quality of valve spring wire while maintaining high process stability and economic efficiency.
The products
Surface Defect Detection
DEFECTOMAT PRODUCT FAMILY
Surface Defect Detection
CIRCOGRAPH Product Family
Contactless eddy current inspection for reliable detection of longitudinal surface defects on bright products