Measuring Oil-Film Thickness on a Coil or Sheet Surface

The oil film on the surface of a coil or sheet finds use as a coolant and lubricant in the rolling process; acts as an anti-corrosion barrier during storage; and provides a critical lubricating layer during stamping. Material with insufficient oil can lead to difficulties in the forming process, resulting in defective stampings, increased tool wear, unnecessary stoppages and lost production. Conversely, material with excessive oil deposits can lead to downstream production problems, panel welding and adhesion issues and painting and lacquering difficulties, as well as have a negative environmental impact.

To provide metalformers with a reliable and dependable process to instantly and accurately measure lubricant thickness, and to determine its distribution across the complete coil or sheet surface, Amepa GmbH (Amepa America Inc., Middleburg Heights, OH) has introduced an oil-film measurement (OFM) system. It’s based on Lambert Beers Law, which states that the thickness of lubricant is directly proportional to the amount of light it absorbs.

Using infrared spectroscopy, OFM technology directs a source of infrared light through the lubricating layer. As the light passes through the oil, wavelengths of light are intensely absorbed by the lubricant, irrespective of its grade or viscosity. An optical detector collects the remaining light reflected from the surface of the strip, allowing the system to accurately determine lubricant thickness.

Metalformers can acquire OFM technology in three setups: an automatic inline, real-time system that constantly and simultaneously scans both sides of a coil; a table-mounted version for precut blanks and sheets; and as a portable hand-held device.

See also: AMEPA America Inc.

Technologies: Lubrication, Quality Control

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