English 
The core advantages and characteristics of round bearing silicone sealing pads
The round bearing silicone sealing gasket is specially designed for the circular structure of the bearing. Combining the characteristics of silicone material and the requirements of sealing function, it has irreplaceable application value in the field of industrial machinery. The specific advantages and characteristics are as follows:
I. Strong material adaptability, meeting the core requirements of bearing conditions
1. Wide temperature range is stable, adaptable to multi-scene temperature fluctuations
The temperature resistance range of silicone material reaches -40℃~200℃ (the special formula can be expanded to -60℃~250℃), which can adapt to the temperature changes of the bearing during start-stop and high-speed operation (such as the heating of motor bearings and the low-temperature environment of outdoor equipment). It will not be hardened, brittled or softened due to alternating cold and hot, and long-term Hold the sealed elastic.
2. Excellent chemical stability, oil resistance and corrosion resistance
It has strong resistance to lubricating oil, grease (such as mineral oil, synthetic oil) commonly used in bearings and dust, water vapour, weak acid and alkali and other media in the industrial environment. It does not swell and does not age, which can effectively prevent oil leakage and impurities from invading the bearing, and prolongs the bearing lubrication cycle.
3. The elastic rebound is good, which compensates for the assembly error.
The Shaw hardness of silicone can be customised (50A~80A), with excellent compression rebound rate (when the compression rate is 20%, the rebound rate is ≥90%), which can compensate for the assembly gap between the bearing and the bearing seat, the processing tolerance, and the slight vibration displacement during bearing operation, and always maintain a tight fit to avoid "sealing loss Effect".
II. Circular structure design, accurately matching the bearing sealing scene
1. The shape is fully adapted, and the sealing fit is high.
It is accurately matched with the round inner ring/outer ring of the bearing and the round mounting hole of the bearing seat. There is no redundancy of edges, and the sealing surface can achieve "seamless fit throughout the whole circle". Compared with the shaped sealing pad, it can minimise the sealing blind area and prevent dust and impurities from entering the gap.
2. It can integrate the functional structure and enhance the sealing effect.
Special structures can be customised according to the bearing type (such as deep groove ball bearings, tapered roller bearings):
◦ Lip-shaped sealing design: the inner ring of the sealing gasket increases the elastic lip mouth, fits the rotating surface of the inner ring of the bearing, and has both "dynamic sealing" (anti-oil leakage) and "static sealing" (dustproof);
◦ Groove/convex structure: the outer ring is designed with a ring groove, which is coordinated with the raised positioning of the bearing seat to prevent the sealing gasket from shifting when the bearing is running;
◦ Composite layer design: the surface composite polytetrafluoroethylene (PTFE) coating reduces the friction coefficient with the rotating surface of the bearing and reduces wear.
III. The sealing performance is reliable and the service life of the bearing is extended.
1. Multi-dimensional sealing, blocking "double threat"
At the same time, "anti-leakage" and "anti-intrusion" are realised: on the one hand, it prevents the lubricanting oil inside the bearing from being thrown out by centrifugal force; on the other hand, it prevents external dust, metal debris and water vapour from entering the bearing track to avoid "abrasive grain wear" and "rust and jamming", which can extend the service life of the bearing by 30% to 50%.
2. Wear-resistant, fatigue-resistant, adapt to long-term dynamic operation
The structure of the silicone molecular chain is stable, and the tear strength is ≥15kN/m. When the bearing rotates at high speed (such as the rotation speed ≤3000r/min), the friction loss with the bearing surface is small. After 1000 hours of dynamic wear testing, the thickness loss of the sealing surface is ≤0.1mm, no cracks and no damage, suitable for long-term Continuous working conditions.
IV. Convenient installation and maintenance, reducing the cost of use
1. Lightweight, easy to install, adaptable to automated assembly
The density of silicone is only 1.1~1.3g/cm³, light in weight and good flexibility. It can be directly inserted into the outer ring of the bearing or embedded in the groove of the bearing seat without complicated tools; some styles can be designed with "self-positioning convex" to avoid misalignment during installation, adapt to the automated assembly line, and improve production efficiency.
2. Easy to clean and low maintenance cost
The surface is smooth and not easy to stick to dust. During daily maintenance, you only need to wipe it with alcohol or neutral detergent. Silicone ageing is slow, and its service life can reach 3 to 5 years under conventional working conditions. There is no need to replace it frequently, which reduces downtime and maintenance and accessories costs.
V. High degree of customisation, suitable for special bearing needs
1. The dimensional accuracy can be controlled to meet the requirements of precision bearings.
The round size tolerance can be controlled at ±0.05mm, which is suitable for micro bearings (such as diameter less than 10mm) to large industrial bearings (such as diameter more than 500mm). The inner ring aperture, outer ring diameter and thickness can be customised on demand to accurately match the sealing space of different models of bearings.
2. Functional modular customisation
Additional functions can be added according to special working conditions:
◦ Flame-retardant type: add flame retardant, pass UL94 V-0 certification, adapt to high-risk scenarios such as motors and wind power;
◦ Conductive type: filled with conductive carbon black to eliminate static electricity generated by bearing operation and avoid electrostatic breakdown or spark ignition;
◦ With skeleton type: embedded metal skeleton (such as steel ring, copper ring), enhance structural rigidity, and adapt to high-pressure and high-load bearings (such as hydraulic pump bearings).
VI. Environmental protection and compliance, in line with industrial standards
It uses food-grade/industrial-grade silicone raw materials and has passed RoHS 2.0, REACH and other environmental protection certifications. It is free of heavy metals and halogen-free release, and can be used in bearing sealing scenarios with strict environmental protection requirements such as medical equipment and food processing machinery; some products can provide MSDS (material safety data sheet) and Third-party sealing performance test reports (such as oil-resistant swelling test, compression rebound test) meet the requirements of industrial compliance.
In summary, the core value of the round bearing silicone gasket is: based on the "elasticity + weather resistance" of silicone material, taking the "precise adaptability" of the circular structure as the core, through functional design and customisation ability, it realises the "long-term sealing, working condition adaptation, low-cost maintenance" of the bearing, which is the first of industrial bearing sealing. One of the optional accessories.
FAQ:
The following are the frequently asked questions and professional answers of round bearing silicone sealing gaskets, focussing on the core requirements of bearing sealing (dustproof, oil-proof, temperature-resistant, sealing performance), and providing technical reference in combination with industrial application scenarios:
I. Material selection and performance
Q1: What material is used for the round bearing silicone gasket? Which scenes are suitable for different materials?
• Core material:
1. Ordinary silicone (VMQ): temperature-resistant -40℃~200℃, suitable for dry, oil-free/light oil environments (such as dust-proof sealing of motor bearings), low cost but poor oil resistance.
2. Fluorosilicone rubber (FVMQ): Introduce fluorogroup, resistant to mineral oil and hydraulic oil, temperature-resistant -60℃~250℃, suitable for oil-immersed bearings such as automobile engines and gearboxes.
3. Silicone + metal skeleton: enhances rigidity and prevents the deformation of the gasket. It is used for high-pressure and high-speed bearings (such as machine tool spindle bearings).
• Selection principle: fluorosilicon rubber must be selected for scenes of contact with mineral oil and high temperature (>150℃); skeletonless type can be selected for static sealing, and skeleton-free for dynamic sealing (bearing rotation) is required.
Q2: How to measure the sealing performance? What is the key indicator of non-oil leakage?
• Core indicators:
◦ Compression permanent deformation rate: tested according to ASTM D395 standard, the deformation rate ≤20% after 200℃×70h is qualified (the larger the deformation, the worse the sealing).
◦ Oil-resistant volume expansion rate: The expansion rate of fluorosilicone rubber is ≤30% after 150℃×70h in IRM903 oil. Excessive expansion is likely to cause the sealing cavity to be stuck.
◦ Lip contact pressure: During dynamic sealing, the contact pressure between the lip and the outer ring of the bearing should be maintained at 0.1~0.3MPa. If the pressure is not enough, it is easy to leak liquid, and if it is too large, it will aggravate wear.
• Key design: The lip-shaped sealing gasket (not the flat pad) realises dynamic sealing through "lip-mouth elastic fitting", which is the core structure of bearing leakage prevention.
Q3: How much pressure and speed can it withstand?
• Pressure-resistant range: static sealing ≤10MPa, dynamic sealing (when the bearing rotates) ≤3MPa, if exceeded, an enhanced model with a metal skeleton should be selected.
• Speed resistance: the ordinary model is suitable for ≤3000r/min, and the fluorosilicone rubber + skeleton model is suitable for ≤5000r/min (too high speed is easy to cause heat and ageing of the lips).
II. Installation and adaptation
Q4: What preparations need to be made before installation? What are the consequences of incorrect installation?
• Installation steps:
1. Cleaning: Wipe the surface of the bearing seat sealing groove and gasket with anhydrous alcohol to remove iron shavings and oil stains (impurities will scratch the lips and cause oil leakage).
2. Positioning: Make sure that the lip mouth of the sealing gasket is facing the medium side (such as the direction of the oil chamber). The skeleton-free model should avoid stretching deformation during installation.
3. Compression: The compression rate of the sealing gasket is controlled at 20%~30% (e.g. the gasket with a thickness of 5mm is compressed to 3.5~4mm after installation). The compression is not enough to leak liquid, and excessive tightness will cause the bearing to be stuck.
• Common error consequences: lip and mouth reverse → 100% leakage; compression rate >40% → permanent deformation of the sealing gasket, failure within 3 months; impurities on the surface → lip and mouth wear, oil seepage within 1 month.
Q5: How to match the bearing size? What is the tolerance requirement?
• Size adaptation: The inner diameter of the sealing gasket should be 0.5~1mm smaller than the diameter of the outer ring of the bearing (over-matching), and the outer diameter should be 0.2~0.5mm larger than the inner diameter of the sealing groove (to prevent displacement).
• Tolerance standard: according to GB/T 3452.1-2005 (O-shaped rubber seal for hydraulic and pneumatic), diameter tolerance ≤±0.1mm, thickness tolerance ≤±0.05mm (precision bearings need higher precision).
• Customised tips: Provide the bearing model (such as 6205 deep groove ball bearing) or the sealing groove size (inner diameter × outer diameter × depth), and the manufacturer can directly match the standard model.
Q6: Do I need special tools for installation?
• Conventional tools: rubber mounting sleeve (to avoid scratching the lips with hard objects such as screwdrivers), torque wrench (control the bearing end cover to tighten the torque to prevent the sealing pad from being unevenly loaded).
• Special scenarios: high-speed bearings (>3000r/min) need to be coated with food-grade silicone oil (lubricate the lip to reduce initial wear), and the use of butter (which will corrode silicone) is prohibited.
III. Causes and solutions for failure
Q7: What are the common causes of oil leakage in sealing gaskets? How to solve it?
Failure reasons and solutions
1. The material is wrongly selected (ordinary silicone is used in oil environment) and replaced with fluorosilicone rubber material
2. Lip wear (excessive speed or impurity scratch) Reduce the speed/clean the sealing cavity and replace the sealing pad with wear-resistant coating
3. Insufficient compression rate (too loose installation) Re-adjust the gap of the bearing end cover to ensure the compression rate of 20%~30%
4. Ageing of the sealing gasket (long-term high temperature) Replace high-temperature resistant fluorosilicone rubber, or add a bearing heat dissipation device
Q8: What is the reason for the deformation and cracking of the sealing gasket?
• Causes of deformation:
◦ Excessive stretching during installation (non-skeleton models are prone to occur);
◦ Poor media compatibility (such as swelling caused by contact with ester-type synthetic oil).
• Causes of cracking:
◦ Low-temperature embrittisation (low-40°C low-temperature resistant formula is not selected);
◦ Long-term compression leads to stress fatigue (compression rate > 35%).
• Solution: Choose phenyl-containing silicone in low-temperature scenarios; when the type of oil is unknown, fluorosilicone rubber is preferred; control the compression rate within a reasonable range.
Q9: Is it normal for the gasket to heat up when the bearing is running?
• Normal range: the temperature is 5~10℃ higher than the bearing body (lip friction heat), the maximum is not more than 80℃.
• Abnormal fever: when the temperature is >100℃, it needs to be checked:
1. Whether the compression rate is too large (too tight leads to increased friction);
2. Whether the lips are worn (metal friction produces high temperature);
3. Whether the lubrication is insufficient (need to be coated with silicone oil).
IV. Life and maintenance
Q10: How long is the normal service life? When do you need to replace it?
• Life span:
◦ Ordinary silicone (dry environment): 1 to 2 years;
◦ Fluoro silicone rubber (oil-soaked environment): 2~3 years;
◦ High-speed bearings (>3000r/min): about 1 year (requires regular inspection).
• Change the signal:
1. Oil seepage and oil stain accumulation appear on the bearing end cover;
2. There is an abnormal sound when the bearing is running (the gasket is stuck or worn);
3. Cracks, hardening or deformation appear on the lip of the sealing gasket.
Q11: How to maintain it on a daily basis?
• Regular inspection: clean the bearing end cover every month to observe whether there are traces of oil seepage; touch the sealing pad by hand every 3 months to check whether it is hardened.
• Lubrication and maintenance: Apply a special silicone lubricant every 6 months in the dynamic sealing scene (it is forbidden to use engine oil, it will corrode silicone).
• Storage requirements: Unused pads should be sealed and stored in a dry environment below 25 ℃ to avoid direct sunlight (UV accelerated ageing).
V. Customisation and compliance
Q12: What customised requirements are supported?
• Structural customisation: lip shape (single lip/double lip), flat pad, with skeleton/no skeleton, with positioning hole (to prevent rotation).
• Performance customisation:
◦ Temperature resistance: -80℃~300℃ (special formula);
◦ Wear resistance: add polytetrafluoroethylene (PTFE) filler;
◦ Flame retardant: UL94 V-0 level (suitable for explosion-proof equipment).
• Size customisation: the minimum inner diameter is 5mm (micro bearing), the maximum outer diameter is 500mm (large mechanical bearing), and the tolerance can reach ±0.03mm.
Q13: What certifications are required for industrial scenarios?
• Basic certification: ISO 9001 (quality management), ISO 16232 (automotive industry cleanliness).
• Special certification:
◦ Food machinery: FDA 21 CFR 177.2600 (food contact safety);
◦ Automotive industry: IATF 16949 (auto parts standard);
◦ Environmental protection requirements: RoHS 2.0 (restrict heavy metals).
VI. Selection suggestions
1. Motor bearing: choose fluorosilicone rubber double-lip skeleton model (dustproof + anti-bearing grease leakage), temperature resistance ≥150℃.
2. Automotive gearbox bearings: fluorosilicone rubber must be selected, which needs to pass the transmission oil resistance test (150℃×1000h expansion rate≤25%).
3. Micro-precision bearing: choose ultra-thin without skeleton (thickness 1~2mm) with a tolerance of ±0.03mm to avoid affecting the accuracy of the bearing.
4. High-temperature equipment bearings: choose silicone with ceramic filler, with temperature resistance ≥250℃, and cooperate with the metal skeleton to enhance rigidity.
Through the above answer, it can be accurately selected according to the bearing type and working conditions (temperature, medium, rotation speed) to avoid equipment failure caused by sealing failure.
