(From the June 27, 2011, issue of Rubber & Plastics News)
PLYMOUTH, Mich.—A proprietary process that allows Simrit to apply a friction-reducing coating to its products will improve seal function and increase the durability of seal performance, according to the division of Freudenberg-NOK G.P.
This advanced surface treatment process is known as the Reduced Friction by Nanotechnology method. It isn't new but is quickly becoming a more viable option for customers that experience specific challenges, Simrit said.
Among the many benefits to this process is that it reduces the friction and stick-slip manufacturers can experience, the firm said. For example, it improves the efficiency in diaphragms as it reduces the energy required to actuate the diaphragm.
Sealing components made of elastomeric materials have inherently high surface energies or tackiness and a high coefficient of friction. As a result it is common that when an elastomeric seal makes contact with the mating component, the interface of the two surfaces can produce a detrimental “stiction” effect when the contact is intermittent, Simrit said.
This “stiction” phenomenon can have a significant impact on numerous applications, such as bicycle shock absorbers, which need to have a low breakaway force for smooth shock function.
“This can also make installation easier as it reduces the installation force needed,” said Steve Koch, Simrit marketing director, Special Sealing Products Division.
One of the benefits of RFN is that it is a very durable solution that can be used for a longer period of time, Koch said. It provides an added level of longevity and inertness that is highly desired for customers. The reason for that durability is based on the way it is applied to the elastomer. Some polymers can cause friction but RFN won't stick.
RFN-treated surfaces have consistently shown a 70-percent reduction in static COF, aggressive media resistance and lower torque and loading properties, according to the company. There has been no increase in COF in treated surfaces for fuel, ozone and wear. But Simrit claims that in its tests non-treated surfaces have exhibited an 80- to 100-percent increase in COF.
“When you reduce friction, you reduce heat,” Koch said. “That results in a longer life. And it really highlights the durability and functionality that is inherent.”
The ability to create more robust seals requires the prevention of stiction. The RFN process consists of applying its proprietary surface modification to rubber components to reduce COF. The transformed surface, according to Simrit, offers high abrasion resistance, low COF, resistance to aggressive fluids and improved long-term service.
Customers, though, will put RFN through significantly rigorous testing, such as a valve actuator test where each valve is cycled numerous times as a way to test its durability, including the electronic components.
The RFN treatment is odorless, trans¼lucent in color and compatible with applications that require purity. The firm said applications that require low stiction and long service life, such as valve-sealing components and diaphragms, can greatly benefit from Simrit's RFN treatment.
It was developed in Germany several years ago and first brought to the U.S. in 2007. Over the last couple of years, Simrit representatives have seen a strong increase in volume as more customers become interested and learn about it. Of course not all customers will require RFN.
“You really are going to be interested in this if you have significant friction or stiction,” Koch said. “It's a pretty robust product used for intense applications.”
For Simrit, the RFN process has given it a strong competitive advantage.
“RFN allows us to take standard compounds and enhance the features while still keeping the cost down,” Koch said. “We can add value by using fewer parts and reduce the design complexity, again leading to a cost reduction.”
There is no set price because that will depend on the product being sealed, Koch said. And it can be applied to diaphragms, O-rings, gas cap seals and solenoid valve seals.