Global technology company SKF’s two-year growth plan has been so successful that it will soon be extending its standard range of rotary- shaft seals, which is currently available from 6 mm up to 250 mm shaft diameter, up to 540 mm diameter. This will enable the company to offer sealing solutions to previously untapped markets and appli- cations, reports SKF Southern Africa platform manager André Weyers.
SKF has invested in a special rotary-shaft seal range that offers effective sealing ability and wear resistance for increased seal life or mean time between failures.
“SKF rotary-shaft seals have, over the past four years, been used with leading original-equipment manufacturer (OEM) gearboxes and electric motor manufacturers globally,” he says, adding that these successes have been mirrored in South Africa.
“The OEMs have done research on quality and they know what they want when it comes to reliable sealing solutions. Designed in accordance with ISO 6194 and DIN 3760 specifications, our rotary shaft seal range outperformed other top European brands during extensive independent testing. This is why they meet the OEMs discerning requirements on all fronts – range, quality, reliability, life span and price,” he explains.
Weyers highlights a number of reasons for the company’s global success in sealing solutions, saying that “seals are part of our global core technologies – bearings and units, mechatronics, power transmission, condition monitoring and related engineering services”.
SKF is currently the fifth-largest seal manufacturer worldwide and as part of the company’s growth plan to become one of the largest international seal manu- facturers, it has embarked on an aggressive acquisition drive. This includes the proven Chicago Rawhide brand, which was successfully integrated into SKF 17 years ago, he says.
SKF’s successes in sealing solutions can be further attributed to its global presence. With representation in more than 130 countries and 18 seal manufacturing units worldwide, the company has the ability to not only supply a range of high-quality seals but also to offer customers product support, notes Weyers.
Maintaining sealing integrity is vital to prevent equipment failure, which can cause serious harm to the environment, operators and manufacturing processes, adds Weyers. The quality of a seal is directly related to the quality of the seal material. Overall lip design, operating conditions – such as temperature and pressures – as well as the correct seal selection all play a vital role in seal performance.
With the development of two new seal material compounds, nitrile (NBR) and Viton FKM, SKF has addressed the wearing of the seal lip by making the spring tension and lip flex more effective. Although we have no control over shaft surface finishes it remains a vital aspect that can significantly reduce the life span of a seal and lead to premature failure. In addition to offering higher wear resistance, NBR and FKM are ideally suited to adverse environments such as hot and/or wet conditions.
The rubber outside diameter of the SKF rotary-shaft seal provides better sealing ability in the housing as well as considerable surface roughness. The nitrile rubber compound features good resistance to ageing, compatibility with synthetic oils, good pumping ability and wear resistance. “For applications with temperatures beyond the limits of nitrile rubber, we recommend FKM,” adds Weyers.
Additional features of the SKF rotary-shaft seals range include a spring-loaded and trimmed sealing lip, which enables a quick response to handle dynamic run-out and to maintain the sealing ability. The well-balanced sealing lip and flex section is able to follow the shaft effectively to withstand high dynamic run-out and shaft-to-bore misalignment. A beaded outside diameter provides an improved sealing ability and a secure retention in the bore. It also prevents spring back during assembly. The secondary sealing lip is designed with zero lip/shaft interference to avoid the creation of additional friction, which results in heat genera- tion and energy loss.
Featuring one design across the range, SKF rotary-shaft seals are successfully used in coaxial, worm-geared, right-angled, parallel shaft, input and output shaft motors, but Weyers points out that the seal range is not limited to gearboxes and electric motors. “The seals can be and are used successfully in any rotating equipment application.”
Equally important, says Weyers, is the availability of stock. “To increase the effectiveness of the supply chain and to keep customers’ downtime to a minimum we work closely with and listen to our customers’ requirements, analyse their demand frequencies and base our stockholding around our customers’ needs and production schedules.”
In addition, SKF is able to bring its rotary-shaft seal range to its customers’ doorsteps through the company’s countrywide network of authorised distributors.
“Our sealing solution extends far beyond just product supply. Through the com- pany’s solutions approach, SKF can help customers select the correct materials to suit the particular application they are using, and offer advice and training on correct handling, storing and installation processes,” concludes Weyers.