The choice of the right sealing solution decides the performance and the life of an engineering system. With stainless steel shafts that have not been hardened, designers face particular challenges. VR radial shaft seals offer a solution here — with clearly defined application limits, which we state openly.
The problem with unhardened stainless steel
Stainless steel shafts are used in food processing, medical technology and the chemical industry for their corrosion resistance. Without hardening, however, they bring three drawbacks:
- Susceptibility to wear: standard seals damage the soft shaft surface.
- High friction: conventional seals raise energy consumption and generate more heat.
- Costly post-treatment: nitriding, hard chrome plating or other hardening processes cost time and money.
Where unhardened stainless steel shafts are suitable
Not in every application. VR radial shaft seals deliver optimum performance under these conditions:
- Moderate pressure and moderate speed. Suitable up to about 6 bar and 5 m/s circumferential speed.
- Non-abrasive media. Ideal for clean media such as water, oils or air. Abrasive media damage the shaft surface and shorten service life.
- Optimised shaft surface. Roller-burnishing the running track is an inexpensive step that improves hardness and roughness values and extends seal life considerably.
- Alternative for more demanding conditions. At high pressure, high speeds or with abrasive media, non-corroding shaft sleeves are the practical solution.
Why VR seals work here
- The shaft surface is preserved. Precisely preloaded radial and tangential sealing lips prevent destructive running-in marks.
- No post-treatment needed. Hardening the shaft is unnecessary — which saves time and cost.
- Less friction, less energy. The design minimises friction and improves the energy efficiency of the application.
- Long service life within the defined window. As long as the limits named are observed, these seals are very durable.
Typical fields of use
- Food and pharmaceutical industry: mixers, pumps, packaging machines. Easy to clean and corrosion-resistant.
- Medical technology: pumps, centrifuges, instruments and sensors. Also suitable for capillary tubes from 0.6 mm diameter.
- Marine and subsea technology: propeller shafts and underwater robotics, where high corrosion resistance is called for.
Sustainable as a side effect
- Recyclability: no chemical bond between metal and elastomer part, hence separation by type.
- Energy saving: lower friction losses reduce consumption in the application.
- Recyclate content: the design permits a high proportion of recycled materials without impairing quality.
Conclusion
For unhardened stainless steel shafts, VR radial shaft seals are the fitting solution — provided pressure, speed and media properties stay within the recommended limits. For more demanding conditions, shaft sleeves are the effective alternative.