Sealing Products
Product Features
1.Two Main Structural Types: Determining Speed and Protection Level
● Contact sealing (e.g., rubber lip seal, code "RS"): The lip tightly contacts the inner ring groove. Excellent protection, effectively prevents dust and water, but generates more friction heat at high speeds; the limit speed is typically 20%-30% lower than non-contact types.
● Non-contact sealing (e.g., metal dust cap "Z" or clearance seal "RZ"): Has an extremely narrow labyrinth clearance (no direct friction). Low friction torque and heat generation, suitable for high-speed conditions, but provides weaker protection against fine dust and liquids.
2.Key Material Features: Determining Temperature and Media Resistance
● Nitrile rubber (NBR): Most common, good oil resistance, typical operating temperature range -30C to +120C.
● Fluoro rubber (FKM/Viton): High temperature resistance (up to 200C) and acid/alkali corrosion resistance, higher cost.
● Silicone rubber (VMQ): Suitable for extremely low temperature environments down to -60C.
● Metal dust caps: Typically SPCC cold-rolled steel, no upper temperature limit, but no elastic compensation and prone to deformation.
3.Key Performance Parameters (Critical Selection Indicators)
● Linear speed (limit speed): Contact-type rubber seal lips have linear speed limits (typically less than 15-20 m/s); overspeed can cause lip ablation or squealing.
● Static and dynamic sealing: Contact types effectively prevent splash water in static conditions; however, during dynamic rotation, under centrifugal force, the grease leakage rate (approximately 0.5-2g/year) is the core quality metric.
● Friction torque: Nearly zero for non-contact types; contact types generate additional torque loss, affecting motor power consumption.
4.Installation and Maintenance Features (Special Notes)
● Built-in maintenance-free: Bearings with seals are pre-filled with grease at the factory; before installation, heating, cleaning, or kerosene soaking are strictly prohibited, as this will wash away the grease and damage the rubber lip.
● Unidirectional: Some seals have directionality (dual-lip design); during installation, ensure the seal lip faces the grease side to utilize the "pumping effect" to draw oil back inside.
5.Special "Breathability" and "Noise Reduction" Design
● High-end seals have pressure relief grooves at the lip to prevent internal negative pressure that sucks in dust during high-speed rotation.
● Optimizing the lip waveform (e.g., sine wave) can reduce friction vibration and lower noise by 3-5 decibels.
Summary:
Selecting a seal is about finding the balance between protection requirements and speed loss. If the working environment is humid and dusty, prioritize contact-type (RS); if it is an ultra-high-speed spindle, prioritize non-contact dust caps (Z); if strong acids or alkalis are involved, fluoro rubber (FKM) material must be specified.
Applications of Bearing Sealing Products
The applications of bearing sealing products are extremely broad, with core value in preventing pollutant intrusion, preventing lubricant leakage, thereby protecting bearings and extending equipment life.
● Automotive Industry: The largest application market. Widely used in wheel hub bearings, engines, transmissions, drive shafts, steering systems, generators, etc. Especially in new energy vehicles, low-friction sealing technology is crucial for extending range.
● Aerospace: Extremely demanding requirements. Used in aircraft engine bearing chambers to prevent lubricating oil leakage and high-temperature airflow intrusion; also used in airframe rod-end bearings and other flight control components.
● Energy and Heavy Industry: Used in wind turbines, requiring long life and high reliability; used in water pumps to cope with fluid erosion and contamination; used in harsh environments prone to contamination such as mining, construction, papermaking, and agriculture; also used in oil and gas extraction.
● Food and Beverage: Food-grade (NSF H1 certified) materials and corrosion-resistant stainless steel must be used to prevent lubricant contamination of products, and to withstand frequent high-pressure water washing.
● Other Industrial and Emerging Fields: Covering motors, medical equipment, semiconductor manufacturing, printing, and construction machinery.
In summary, from automobiles to aircraft, from food processing to wind power, bearing sealing products are key components ensuring the reliable operation of modern industrial equipment.
Installation Precautions for Bearing Sealing Products
When installing bearing sealing products (whether bearing assemblies with seals or independent shaft seals), the core principles are to prevent lip damage and ensure correct orientation. Sealing components are extremely fragile; one installation mistake can lead to direct scrapping.
1.Before Installation: Strict Inspection and Guidance
● Deburring and chamfering: Sharp edges and burrs on the shaft journal or housing bore are the "number one killer" of seal lips. Before installation, be sure to repair these and set a 15-30 degree guide chamfer at the entrance, apply grease transition to prevent lip curling or scratching.
● Cleaning: Iron filings or sand particles are strictly prohibited; during rotation, they will grind the seal lip and shaft diameter.
2.Core of Force Application: The Force Point Must Be Correct
● Installing bearings with seals (e.g., 6202-2RS): The pressing force must act on the "outer ring" end face. If pressing through the inner ring, force is transmitted through the rolling elements, causing raceway indentations and seal deformation, directly scrapping the bearing.
● Installing independent shaft seals: The pressing force must act on the seal metal casing end face. Striking the rubber portion where the seal lip is located is absolutely not allowed.
3.Direction and Orientation: The "Pumping Effect" of the Lip
● The main seal lip must face the side of the medium being sealed (lubricating oil/grease). Installing backwards will cause a "pumping effect" during high-speed rotation, drawing internal grease out and actually sucking external dust in.
● For double-lip seals with a dust lip, the secondary lip (spring-free side) faces outward (dust protection).
4.Absolute Prohibition: Never Clean "Sealed Bearings"
● Bearings with seals (suffix RS/2RS) are pre-filled with grease at the factory; before installation, "NEVER" soak them in kerosene or gasoline for cleaning! Cleaning agents will dissolve the internal dedicated lubricant and corrode the rubber lip, causing the bearing to "dry grind" and burn out. These bearings should be installed directly after opening.
5.Environment and Temperature Control
● Heating limit: If hot mounting is necessary, the heating temperature must not exceed 80C (ordinary NBR rubber lips will harden and fail above 120C).
● Eccentricity compensation: During installation, the seal and shaft must be concentric.
6.Special Techniques for Independent Oil Seals
● Oiling: Before installation, be sure to apply a thin layer of lubricating grease (or specialized assembly oil) on the seal lip to prevent "dry friction" from burning the lip during initial startup.
● Specialized tools: Specialized pressing sleeves must be used to ensure uniform pressure. Striking directly with a hammer is strictly prohibited.
Direction toward oil, press on outer ring, never clean, oil to prevent dryness.
