Edge build-up measurement

A method for inspecting, on a metallic coated coil being wound, a coating thickness homogeneity, the method comprising the following steps:

• A) measuring a first distance D1 between a first reference point R1 and a first point C1 on a coil surface of the metallic coated coil by a first sensor,
• B) measuring a second distance D2 between a second reference point R2 and a second point C2 on the coil surface, the first and second points C1, C2 being situated at different spots along a coil width W of the metallic coated coil by a second sensor;
• C) computing a difference between the first distance D1 and the second distance D2 with a computer, the difference being denoted as difference Δ12true;
• D) saving the difference Δ12true to the computer;
• E) repeating steps A, B, C and D while moving at least one of the first point C1 or the second point C2 on the coil surface along at least a tenth of an entirety of the coil width W by displacing said first sensor and/or second sensor along the coil width W;
• defining a threshold value M;
• comparing each saved difference Δ12true to the threshold value M or comparing a sum of differences Δ12true to the threshold value M;
• and
• emitting an alert when said difference Δ12true or said sum of differences Δ12true is higher than said threshold value M, wherein a build-up profile is generated by the computer using said saved differences Δ12true.