Title

EARLY DETECTION OF INTERNAL INCLUSIONS AND SHELL DEFECTS USING MAGNETIC FLUX LEAKAGE

EARLY DETECTION OF INTERNAL INCLUSIONS AND SHELL DEFECTS USING MAGNETIC FLUX LEAKAGE

Authorship

Schwarzmann, Jakob

Schwarzmann, Jakob

I am this author

DOI

10.5151/2594-5297-39876

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Abstract

Thin steel strip can contain non-metallic impurities like inclusions and segregations (NMI). They can vary widely in shape and size. The presence of NMIs can cause problems during the further processing of the material, especially during deformation. This creates the demand for a contactless online inspection system for the detection of NMIs to ensure the required product quality. IMS developed an online inspection system for NMIs based on magnetic flux leakage (MFL). MFL is already widely used in offline applications as magnetic powder testing. Compared to hall sensors, the use of sensitive GMR sensors leads to an increase in liftoff while improving sensitivity. The Sensors, magnetization, amplification, and digitalization are incorporated into a compact device acting as a MFL line camera. These devices can be combined in different numbers and configurations, enabling a gap-free coverage of inspected strip. Their data is transferred to the image processing computer by the standard Gig-E interface. The signals of defects are separated from the background noise and classified by an image processing software. It generates a defect map of the strip showing the different defect classes. That information helps in grading the produced material and in optimizing the production process.

Thin steel strip can contain non-metallic impurities like inclusions and segregations (NMI). They can vary widely in shape and size. The presence of NMIs can cause problems during the further processing of the material, especially during deformation. This creates the demand for a contactless online inspection system for the detection of NMIs to ensure the required product quality. IMS developed an online inspection system for NMIs based on magnetic flux leakage (MFL). MFL is already widely used in offline applications as magnetic powder testing. Compared to hall sensors, the use of sensitive GMR sensors leads to an increase in liftoff while improving sensitivity. The Sensors, magnetization, amplification, and digitalization are incorporated into a compact device acting as a MFL line camera. These devices can be combined in different numbers and configurations, enabling a gap-free coverage of inspected strip. Their data is transferred to the image processing computer by the standard Gig-E interface. The signals of defects are separated from the background noise and classified by an image processing software. It generates a defect map of the strip showing the different defect classes. That information helps in grading the produced material and in optimizing the production process.

Keywords

INTERNAL DEFECTS – INCLUSIONS – MAGNETIC FLUX LEAKAGE – COLD ROLLED STRIP – TIN PLATE –MAGNETIC CAM

[INTERNAL DEFECTS – INCLUSIONS – MAGNETIC FLUX LEAKAGE – COLD ROLLED STRIP – TIN PLATE –MAGNETIC CAM