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How dry is dry? - A critical analysis of surface conditions used in dry metal forming (2017)

Almohallami, A.; Arghavani, M.; Böhmermann, F.; Freiße, H.; Herrmann, M.; Mousav, S.A.; Schöler, S.; Scholz, P.; Tenner, J.; Teller, M.; Umlauf, G.; Wulf, D.; Yilkiran, D.; Maier, H.J.

Dry Met. Forming OAJ FMT 3 (2017) 090-094


In the present study, the surface conditions of workpieces used for dry-metal forming experiments were analyzed. Specifically, the effectiveness of different cleaning approaches was evaluated using x-ray photoelectron spectroscopy, in-frared spectroscopy and wetting experiments. The best cleaning results were obtained using a CO2-based approach. CO2 acts as an effective solvent and as a result of the mechanical impact, it removes material from the surface. In fact, clean-ing results were similar to those achieved by plasma cleaning. However, even simple cleaning with a towel and acetone left only a surface film of less than 100 nm. A residual oil film thickness below 100 nm on the work piece appears suf-ficient to mimic true dry-forming conditions in most cases. In order to determine cleanliness of surfaces used in dry-metal forming, an infrared spectroscopy-based oil film gauge along with a customized extended calibration curve turned out to provide for sufficiently accurate data.

Keywords: cleaning, coating, lubricant, spectroscopy, surface analysis