Adhesive applications on filters are as diverse as the materials they filter. They include:
Rolled seams in oil filters, fuel filters, and air filters are formed by cold rolling the edges of two metal flanges like the lid of a tin can.
Anaerobic sealants and rubber-based solvent sealants seal this seam. The rubber-based solvent sealants tend to be less expensive to buy. However, they are generally more expensive in the overall process when you factor in reject rates, hazardous shipping, and disposal. Also, one must consider that solvent-based products require more sealant per part since only about a third of the material constitutes solids that seal. The other 66% is going into the atmosphere or costly solvent recovery units.
Anaerobic sealants are more environmentally friendly, non-flammable, 100% solids, and lend themselves to automation. Anaerobics cure in the absence of oxygen and the presence of metal at room temperature.
Adhesives bond elastomeric gaskets 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 common for these applications. If both cyanoacrylates and epoxies meet the requirements, choose a product for the desired assembly process.
In oil filters, cyanoacrylate adhesives 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 seat the oil filter properly.
Some people weld metal filter assemblies to the end cap. But manufacturers often prefer to use single part epoxies to bond the filter assembly. The adhesives offer a simpler process that does not damage the media as welding can. Bonding also provides additional assurance of seal because the epoxy is a potting compound and a bonding agent.
Process industry disc-shaped filters made of metal housing and metal mesh media can be welded or sealed. Many choose anaerobics 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. They also 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.
For further help and advice selecting filter adhesives, please contact Permabond or review the filter adhesive brochure.
