The requirements of automotive manufacturers regarding the body of their cars have constantly grown in recent years. Good formability, sufficient strength, good corrosion resistance, recyclability, and last but not least the surface appearance are key factors for manufacturers such as BMW, Audi, and Daimler. To address this concern, Hydro Rolled Products and Polytec jointly developed a new method of measuring the surface appearance of aluminum, especially targeting the automotive industry.
“We saw the need to develop a new surface measurement method,” said Hendrik-Johan Brinkman, head of Technical Customer Service and Product Development Automotive at Rolled Products. “Together with our R&D colleagues in Bonn we invented the ‘Hydro-method,’ a new method that enables us to describe the surface appearance faster, cheaper, operator independent, and at higher accuracy compared to the standard method,”
Roping is a commonly known surface defect known that appears as linear patterns on the surface of rolled and formed aluminum. Once identified, roping patterns can be reduced through adaption of process conditions through the entire process chain. Currently, the method used to measure and quantify the roping value in aluminum sheet is the roping test according to VDA 239-400.
The Hydro-method is designed to be faster, more economical, and more precise than the current means of measuring roping. The method implements TMS-500 TopMap Pro.Surf from Polytec, which uses a white light interferometer to automatically measure the surface topography of sheet samples and determine the roping value. The white-light interferometer recorded 2 million points on the surface in a matter of seconds, ensuring rapid data acquisition of the surface quality of the aluminum sheet.
“With the Hydro-method we are able to characterize the surface topography of our material with a high accuracy,” said Brinkman. “Our customers appreciate our new method. Through our optimizations we could improve the surface appearance at our customers products.”