Inline Measurement of Surface Roughness and Oil Film Thickness – Smart Press Shop Uses Decisive Parameter Data in Galvanized Strip Forming

Abstract

Surface roughness and oiling condition of incoming coils are two critical quality-parameters determiningthe friction between blank and deep-drawing die in galvanized strip forming, in particular the flowbehaviour of the blank pressed around die edges. AMEPA commissioned a unique tribological system atSmart Press Shop in Halle/Saale/Germany, a Joint Venture between Porsche and Schuler Pressen. Theinline system measures surface roughness and oil film of galvanized strips for body in white parts. It isintegrated into the Schuler Track & Trace system. Press parameters are adjusted to each coil processedbased on inline measurements, ensuring perfect forming. An inline Surface Roughness Measurement Sys-tem (SRM system) uses a light-section method. The OFM system measures reflection and absorption ofinfrared light projected onto the strip and calculates the oil film in g/m . If values are not within tolerance,2systems trigger a warning for operators to take immediate action. A key aspect is the system’s capability to adjust press line parameters so that parts otherwise graded as out-of-spec could leave the press line as OK products. Thus, a poorly oiled strip that normally would fail in the forming process can be turned into a “good” strip by re-oiling.