Adhesive Applications on Filters
Filter Adhesives – Adhesive applications on filters are as diverse as the materials they filter. We’ve selected a few common applications that detail how and why adhesives are used.
- SEALING THE ROLLED SEAM ON THE BASE PLATE
- BONDING RUBBER GASKETS TO THE BASE PLATE
- BONDING FILTER ASSEMBLY TO THE END PLATES
- SEALING DISC SHAPED FILTERS
FILTER ADHESIVES FOR SEALING THE ROLLED SEAM ON THE BASE PLATE
Rolled seams are found in oil filters, fuel filters, and air filters. They are formed by cold rolling the edges of two metal flanges like the lid of a tin can. Generally, the “can” is rotated while a stationary set of rollers moves in to crimp the can closed.
Anaerobic sealants and rubber based solvent sealants are used to seal this seam. The rubber based solvent sealants are less expensive by the pound but generally found to be more expensive in the overall process when reject rates, hazardous shipping and disposal are factored in. Also one must consider that solvent based products require more sealant per part since only about a third of the material is solids that seal and the other 66% is going into the atmosphere or costly solvent recovery units.
Anaerobic sealants are more environmentally friendly, nonflammable, 100% solids and lend themselves to automation. Anaerobics cure in the absence of oxygen and the presence of metal at room temperature.
BONDING RUBBER GASKETS TO THE BASE PLATE
Elastomeric gaskets are found on the base plates of oil filters, hydraulic fluid filters, pharmaceutical filters, biomedical filters and food and beverage filters. Choosing an adhesive to attach these gaskets is largely dependent on the temperature and chemical resistance required of the filter. Adhesives with ISO 10993 testing are desired for biomedical applications, and FDA approval is needed for food contact applications. Both cyanoacrylates and epoxies are commonly used. If both cyanoacrylates and epoxies meet the requirements, products are chosen based on the desired assembly process.
In oil filters, cyanoacrylate adhesives are generally used to bond the gasket to the outside of the base plate as they resist upwards of the 200F requirement, and are oil and gasoline resistant. This gasket helps to properly seat the oil filter when it is installed on the engine.
BONDING FILTER ASSEMBLY TO THE END PLATES
Metal filter assemblies can be welded to the end cap but more often manufactures prefer to use single part epoxies to bond the filter assembly. The adhesives offer a simpler process which does not damage the media as welding can and also provides additional assurance of seal because the epoxy is used as a potting compound and a bonding agent.
SEALING DISC SHAPED FILTERS
Process industry disc-shaped filters made of metal housing and metal mesh media can be welded or sealed with an anaerobic or epoxy depending on the end use requirements.
Disc-shaped poly or paper media within plastic housings are assembled via solvent or ultrasonic welding or bonded. Again the temperature and resistance requirements dictate the type of adhesive used, but generally ultraviolet & visible light curable adhesives exceed the bond strength of epoxies on plastics and exceed the fluid resistance of cyanoacrylates. If designing a plastic housing with the intent of bonding the components as opposed to welding, a tapered tongue and groove joint provides maximum assurance of seal.
Don’t hesitate to contact the adhesive manufacturer for recommendations on your specific application.