ADHESION SCIENCE OF RUBBER-TO-METAL BONDING TECHNOLOGY

Engineered rubber-to-metal devices enable key performance attributes for automotive, industrial and aerospace applications.  These critical parts rely on a dependable bond being formed between the rubber and the substrate (typically metal) in order to be successfully used in service.  Historically, several methods have been employed in an effort to achieve a dependable rubber to metal bond.  Initial efforts utilized ebonite, brass plating, multiple tie coats, and polyisocyanates as a means for bonding; however, these methods each had their own shortcomings.  In 1956, a substantial advancement in rubber-to-metal bonding was made when LORD Corporation commercialized its Chemlok^® 205/220 system.  This primer/adhesive system allowed for bonding to a wide variety of available elastomers, while enabling substantial improvements in service performance.  Since this time, numerous advancements have been made with rubber-to-metal adhesive systems to meet the changing requirements of the markets they serve.  Today, rubber-to-metal adhesives are commercially available in a wide variety of forms to meet the needs of the end user.  Both one and two component systems can be used, and they are available under the following categories: solvent-based, low-HAPs, environmentally preferred, and aqueous.  Materials Engineers must carefully consider the importance of selecting a proper adhesive system for their application as these bonds must be capable of withstanding potentially harsh exposure environments.  This paper will discuss the adhesion science involved in rubber-to-metal bonding as well as provide some general considerations for achieving a robust rubber-to-metal bond.