Munich-based chemical Group Wacker, and inpro Innovationsgesellschaft für fortgeschrittene Produktionssysteme in der Fahrzeugindustrie mbH have developed a silicone adhesive-sealant for mounting vehicle oil pans. Sold under the name ELASTOSIL RT 779, the new product adheres to both aluminum and polyamide. Plastic oil pans can now be mounted without mechanical fasteners. ELASTOSIL RT 779 was designed to possess good sealing properties and is highly resistant to oil, heat and dynamic loads. The adhesive can be applied by machine and rapidly cures at room temperature. Inpro is based in Berlin, Germany, and develops advanced production systems in the automotive industry.

ELASTOSIL RT 779 is an advance on ELASTOSIL 76540, a silicone adhesive which was previously used for bonding both polyamide and aluminum oil pans. ELASTOSIL RT 779 outscores its predecessor in terms of processing properties, storage stability and resistance to hot engine oil under dynamic loads.

This self-adhesive, condensation-curing two-part silicone rubber boasts a balanced range of rheological properties. It has a high green strength, but thins enough under shear to enable it to be readily processed on two-component mixing and metering equipment. ELASTOSIL RT 779 also cures rapidly. Even if the container has been in protracted storage, the pot life is just five to ten minutes. Substantial improvements have also been made to the storage stability of the curing-agent component.

The adhesive-sealant provides very good long-term adhesion to aluminum and polyamide, without the need for priming. Just 20 minutes after mounting, the bond is strong enough to allow further operations on the engine and oil pan. This slashes cycle times in the production process. When fully cured, the adhesive has a bond strength far in excess of 0.25 megapascals. As the area of the adhesive surface is several thousand square millimeters, vehicle oil pans bonded with ELASTOSIL RT 779 can still support a weight of over 100 kilograms after years of service. ELASTOSIL RT 779 therefore exceeds all the relevant manufacturing specifications on the mounting of such parts.

As a result of the push to make vehicles lighter, more and more engine oil pans are being made from lightweight materials, such as aluminum and plastic. Until now, such components were bolted to the crankcase. The assembly was then additionally sealed with an adhesive-sealant.