Second-generation prelube oils

24.01.2024 | Salzgitter Flachstahl GmbH

As a reliable partner serving automotive customers, Salzgitter Flachstahl mainly supplies hot-dip and electrolytically galvanized coils for the production of structural parts and outer skin applications. Prelube oils have proven their worth as a suitable forming aid in post-treatment. These oils are also tasked with protecting the galvanized surface from corrosion and are applied electrostatically in the rolling mill in one of the final process steps. Oil redistribution in the coil represents a major challenge here. The pressure distribution of the oil between the coil windings causes the lubricant to flow from the center of the strip to the edge of the coil. In order to significantly improve oil redistribution, second-generation prelube oils are finding increasing use, which exhibit improved flow inhibition as well as better forming properties. As a result, the oil coating can be reduced from the usual 1 g/m² to 0.7 g/m², thereby saving valuable resources. Automotive customers also benefit from reduced oil redistribution, as the oil adhesion of the textured surface is significantly better ensured given thinner oil layers. Despite the reduced quantity of oil, the friction behavior can be considered equivalent to first-generation prelube oils. Moreover, significantly less additional oil needs to be used in the pressing plant, which further reinforces the sustainability performance.

This is aptly illustrated by an exemplary use case at Audi where a global savings potential has been identified as amounting to approx. 40 t/a thanks to the use of 2. generation prelube oils in its press shops. You will find more information on this in the 2021 publication on the website of Blech + Rohre + Profile.

In addition to resource savings, it is evident that less oil escapes from the coil flanks due to the thinner oil layer and the improved run-off inhibition. The following image shows a comparison of two coils after 6 months of storage. As less oil leaks during storage and transportation, cleanliness within the rolling and pressing mills as well as the consignment areas can be improved significantly.

There are several indications from publications and feedback from premium customers that the improved tribological system with a second-generation prelube oil also results in less zinc abrasion in the drawing die. More detailed investigations are planned for the future.

The advantages of second-generation prelube oils can be summarized as follows:
•    Resource savings given reduced oiling in rolling mills and pressing plants
•    Better forming results thanks to more even oil films as a result of reduced oil redistribution
•    Less zinc abrasion in the drawing tool compared to first-generation prelube oils
•    Enhanced cleanliness throughout the entire process chain

If you would like more information on the potential uses of second-generation prelube oils, please do not hesitate to contact our Technical Customer Service and Sales departments.