Norgren Collateral

8 A white paper - Manifold Assemblies The multiple layers of laminated manifolds need to be bonded securely to create a single integrated unit. To some extent, the method used will depend on the end use of the manifold. Bonding Methods There are four methods commonly used to bond the layers of laminated plastic manifolds. Adhesive bonding Here an adhesive interacts with the material of both layers. As it cures, it bonds the layers together. This introduces another material into the unit, which can raise compatibility issues. For example, if the adhesive has a different coefficient of thermal expansion or if it is stronger or more elastic than the plastic substrate, it can put stress on the surface. It is also difficult to control dimensional stability when adhesive bonding, as the thickness of the glue joint can vary or even leave voids. And as the parts being bonded are compressed there is a risk the adhesive will be pressed into the channels, changing their shape and size. Solvent bonding In this method, the material is immersed in solvent to soften it and then the layers are pressed together. The solvent essentially puts the material into suspension, so when the two layers are pressed together and the solvent dissipates, what is left is a single solid piece of plastic. While this protects the integrity of the material, it is quite difficult to control the manifold's dimensional stability in this process. While the two parts to be bonded are in the suspension phase, they can slip against each other, moving the flow paths and other internal features out of alignment. Imprecise bonding can contribute to the carryover and retention of contaminants and debris. Finally, air trapped between layers reduces the visual clarity of the manifold, eliminating one of the key advantages to using plastic.

• Cover