PLYMOUTH, Mich.—Freudenberg-NOK's Sealing Technologies is marketing two new products, one a diaphragm, the other shaft seals.

The firm's Simrit division has introduced a diaphragm design for fluid handling applications such as inkjet printers. The Simriz 481 and 491 designs replace traditional polytetrafluoroethylene foil with a perfluoroelastomer, or FFKM, layer. The FFKM layer is bonded to fluoroelastomer pump diaphragms to improve stroke length, reliability and durability.

The company developed the diaphragm in response to a customer's request for a more efficient system for its inkjet printers. The customer was using PTFE-coated diaphragms, which have tiny pore-like holes. Ink was filling those pores and eventually dried up, imbedding particles into the structure of the PTFE.

This reduced the already limited amount of strokes the structure had, causing the PTFE diaphragm to fail earlier than expected, Freudenberg said.

Freudenberg's solution was to mold the FKM rubber as normal with a layer of fabric overtop for extra strength. Then, instead of bonding it with the traditional PTFE, it bonded a FFKM, which did not have the pores that limited the PTFE. It also increased stroke flexibility.

“One of the things that make us unique in the perfluoro world is that we make the polymer, we mix the polymer into a rubber and we mold the parts,” said Joel Johnson, vice president of tech-nology. “We have the ability to work from the people who actually make the polymer itself all the way through to the people who are molding it.”

Thanks to this vertical production, it only took a year for Freudenberg to develop the product.

Johnson said the diaphragm could be customized for use in metering and dosing pumps if the need for a longer stroke length arises.

“The PTFE foil type of diaphragm is normally used in types of applications where you have aggressive chemicals,” Johnson said.

Reducing shaft runout
Freudenberg Sealing Technologies' Process Seals division has come out with a family of PTFE radial shaft seals designed to withstand high temperatures, high speeds and increased shaft runout. The seals are part of the Simmerring Radiamatic HTS II EWS family of products.

The line is designed to offer industrial users an alternative to mechanical face seals. It combines a PTFE shaft sealing ring and flexible bellows element in one application.

“Normally if you have shaft runout with 0.05 millimeters, you can't use any PTFE shaft seals,” said Rene Piethold, application engineer at Freudenberg Sealing Technologies.

“You have to go over to mechanical seals. Our customers always try not to use mechanical seals because they are too expensive.”

The seals are used in food and beverage filling equipment, aggregates in pharmaceutical and cosmetics industry, gears, compressors and pumps, electric drive systems, mixers, kneaders, and separators.

The Radiamatic HTS II EWS seals were developed in response to a customer request for a seal more resistant to shaft runout than a normal PTFE but without the cost of mechanical face seals. The new line of seals combines Freudenberg's existing PTFE shaft sealing rings with PTFE bellows, which prevents runout separation and leakage.

“Normally this is not manageable due to the inflexible nature of the PTFE,” said Bianca Wolf, product manager at Freudenberg Sealing Technologies.

“Therefore we had to combine the PTFE sealing lip with a flexible element to overcome the shaft runout.”

The seals already are being supplied to customers, and Freudenberg-NOK will display them at Drinktec 2013, a food and beverage industry fair from Sept. 16-20 in Munich, Germany. They are developed in Freudenberg's facility in Hamburg, Germany.

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