Stauff designs its new soft-sealing cutting rings with unique capacity for settling effects compensation

Sectional drawing of a tube connector with the new soft-sealing cutting ring: both seals are well protected and are positioned securely in the secondary area
Photo by Walter Stauffenberg GmbH & Co. KG

New in the Stauff Connect product range and introduced for the first time at the Hanover Trade Fair: FI-WDDS-type soft-sealing cutting rings, which distinguish themselves in particular through their capacity to compensate settling effects, for example, from temperature fluctuations or from pressure pulse and vibration loads in the hydraulic system.

With 24° tube connectors, 37° flared tube fittings and Stauff Form, the newly developed tube forming system, Stauff already offers a varied range for the delicate detachable connection interface in hydraulic tube systems. With the FI-WDDS-type soft-sealing cutting rings, the Stauff Connect range is now being expanded to include another variant.

This design of cutting rings can be used in particular if considerable pressure pulse and vibration loads arise in the hydraulics system, and also for larger temperature fluctuations. In these use cases it cannot be ruled out that settling effects arise, which purely metal sealed connections cannot always compensate – with the undesired consequence that small leaks such as the sweating effect may occur at the connection points.

This risk can be reliably avoided by using soft-sealing cutting rings. This was exactly the motivation of the Stauff designers when developing the new FI-WDDS series.

A core component of the soft-sealing cutting ring is an elastomeric seal, which is positioned so as to stay in place in the rear area of the 24° taper in a groove that has been created and optimised for this purpose. An O-ring placed between the cutting ring and tube protects the second possible leakage path – even in an unfavourable tolerance position. As both elastomeric seals are positioned in the secondary area of the connection, the static and dynamic loads in the system are primarily taken up by the well-proven metallic seal.

The use of FKM (Viton®) as a standard sealing material creates an important precondition for the varied use of the new sealing system when it is used for high temperatures or aggressive media too.

The cutting rings themselves – like all other components in the Stauff Connect product range – are designed as standard with a high-quality zinc/nickel curface coating. With more than 1,200 hours of resistance to red rust / base metal corrosion in the salt spray chamber, according to DIN EN ISO 9227, this offers reliable corrosion protection far beyond the usual market standard up to now. Even after transportation, processing and installation of the components, the requirements defined in the VDMA standard sheet 24576 for tube connections for the highest corrosion protection class K5 are considerably exceeded.

A central requirement in the specifications of the developers was to be able to carry out the installation of the connection system as intuitively as possible. This is ensured by a clearly noticeable increase in force at the installation end – where the cutting ring meets the front face of the system’s fitting body.

The soft-sealing cutting rings of the FI-WDDS series can be supplied for all common metric tubes with an external diameter between 6 mm and 42 mm. They are suitable for nominal pressures of up to 500 bar in the Light Series, or up to 800 bar in the Heavy Series, and exceed the pressure specifications of the ISO, in some cases significantly.

With the usage options for all standard components of the Stauff Connect product range, users of the new cutting ring benefit from high variability and flexibility when adapting the system to individual requirements. Also, there is no need for keeping double stock of similar components with the high risk of components being mixed up.

Another advantage that is gained from the use of soft-sealing cutting rings for the OEM is that they, or their service providers for tube assembly and installation, can considerably reduce the time and expense of cost-intensive checking operations, and can eventually do completely without any reworking. The reassurance of using permanently leak-free tube connections also contributes to an ongoing image enhancement for the OEM among their end customers and users of machinery and vehicles.

Mobile hydraulics (construction, agricultural and forestry machinery, commercial and special vehicles) are among the most important areas of application for the FI-WDDS series. However, soft-sealing cutting rings are also a reasonable alternative to metallic sealing connection systems in stationary hydraulics, e.g. for heavily vibrating machinery.

For more information, please visit http://www.stauff.com.

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