Rubber Bonded Valves
Metal-Rubber Valves: the art of combining materials. A true specialism of Helvoet is bonding rubber on metal or plastic inserts. It is the art of designing the metal inserts with the right properties, develop specific bonding agent and develop specific rubber compound to ensure a proper bonding between the two materials.
Rubber Valves
Important while the end result can only be tested with destructive methods therefore we can only rely on the proper execution of the process.
Products and applications
The valves are a combination of rubber with metal or plastic inserts. These products are used in automotive,-medical, - or industrial applications to stop the flow of gas, vapors or fluids, for instance air, steam, water or others.Most important is to have a reliable seal-off in the specific environment. Mechanical properties, temperature behavior, chemical resistance and other aspects play an important role. Parts are mostly produced in high volume with narrow tolerance. Together with the need for high quality makes this application extremely challenging.
Metal insert design
The properties of the metal inserts are extremely important. Dimensions, roughness, edges and cleanliness need to be the same at all times while the cohesion between bonding agent and metal insert is determined by these properties. Helvoet uses only reliable suppliers with a proven track record, state of the art production machines and a proven quality assurance system in place.
Materials in use are aluminum, brass, steel, thermoplastic, - and thermoset materials.
Rubber compound and bonding agent
The rubber compound and the bonding agent used are tailor made for the application by our material engineers and is compounded by Helvoet. The bonding agent is the ‘glue’ that ensure the proper bonding of the rubber on the insert.
The compound needs to be designed as such that after pressing not only the correct sealing properties are accomplished but the rubber is bonded firmly to the metal. Helvoet offers co-development in design of the complete valve. Next to this Helvoet offers technical expertise in FEA analyze in fluid dynamics to simulate the flow and sealing properties.
Process
The chemical bonding requires the metal surface to be cleaned ultrasonic, blasted and applied with a bonding agent only at those places where rubber should be added. Hereafter the rubber is molded onto the product.
In the search for new opportunities, the replacement of metal by plastic is an issue as well as producing with lead free bonding agent or no bonding agent at all.
PPS can be a good replacement for metal but also other materials like thermoset materials are possible and under investigation at the moment. The result is a lighter product and a simplified (quality, costs) production process.
At the moment, the use of self-bonding liquid silicon rubber on plastic and thermoset is the latest innovation and provides a lot of opportunities in near future.