Special rolling bearings are required for the chemical industry that can withstand aggressive media, high temperatures, and precision demands; often hybrid bearings (ceramic balls, steel rings), plastic bearings with ceramic or glass balls, or full ceramic bearings (e.g., silicon nitride) are used to resist corrosion, enable high speeds, and minimize maintenance.
Key Requirements and Solutions:
- Corrosion Resistance: Standard chrome steel bearings often fail. The following are preferred:
- Hybrid Rolling Bearings: Combination of chrome steel rings and rolling elements made of ceramics (such as silicon nitride, Si3N4) or plastics (PTFE, PEEK).
- Plastic Bearings: Cages and sometimes rolling elements made of plastics like PTFE, with rolling elements made of glass or ceramic to protect against acids and alkalis.
- Full Ceramic Bearings: Rings and rolling elements made from ceramics (e.g., silicon nitride) for extreme resistance.
- High Speeds & Low Friction: Ceramics and plastics reduce friction, enabling higher speeds and improved efficiency.
- Electrical Insulation: Bearings with insulating coatings or hybrid bearings are used when current flow must be prevented (e.g., in frequency converters).
- Dry Running: Some ceramic and hybrid bearings can operate dry or with minimal lubrication, which is advantageous in the chemical industry.
Typical Bearing Designs:
- Deep Groove Ball Bearings: Versatile use, accommodate radial and axial loads.
- Angular Contact Ball Bearings: For combined load conditions.
- Cylindrical Roller Bearings: For high radial loads.
Manufacturers:
- Major suppliers such as Schaeffler, SKF, NSK, NTN offer standard and custom solutions.
- Specialists like CeramTec and SLF manufacture tailored solutions.
Conclusion: The choice strongly depends on the specific application – the aggressiveness of the medium, load, and speed determine the material (standard steel, hybrid,