In industrial equipment, oil seals are critical components that prevent lubricant leakage and contaminant intrusion. TC and TG oil seals, as two mainstream skeleton oil seal models, are often used for sealing rotating shafts, but many customers easily confuse the two when selecting them.
TC/TG Oil Seal Core Definition and Structural Analysis
1. TC Oil Seal: Double-lip fully enclosed, the preferred general-purpose type.
Designation Meaning: “T” represents a double-lip structure (1 main lip + 1 secondary lip), and “C” represents a metal skeleton with a fully rubber-enclosed outer ring.
Typical Structure: Composed of a metal skeleton, rubber sealing body, main lip, secondary lip (dustproof lip), and self-tightening coil spring.
Main Lip: Closely fits the shaft surface, responsible for oil prevention and retaining internal lubricant.
Secondary Lip: Located outside the main lip, responsible for dust prevention, blocking external dust and impurities from entering.
Fully Rubber-Enclosed Outer Ring: Enhances the fit with the mounting hole, improves sealing reliability, and is suitable for non-high-precision mounting holes.
Core Features: Mature structure, moderate cost, dual protection against dust and oil, making it the most widely used general-purpose oil seal.
2. TG Oil Seal: Metal housing, reinforced general-purpose type.
Designation Meaning: “T” represents a double-lip structure, “G” represents a metal housing (some are partially rubber-coated), often resulting in reinforced models such as TG4.
Typical Structure: Metal frame + metal housing + double lips + spring.
Metal Housing: Provides higher structural rigidity, suitable for high-precision assembly and rigid mounting cavities.
Outer Ring Design: Some TG oil seals (such as TG4) have annular external threads for easy installation and to aid in leak prevention.
Lip Optimization: Often uses a multi-lip design (such as triple lip) to improve sealing and load-bearing capacity.
Core Features: Higher rigidity, better pressure resistance, high installation precision requirements, can replace many conventional models such as TC and TB.
Key performance comparison of TC and TG oil seals: TC vs TG
| Comparison Item | TC Oil Seal | TG Oil Seal | Customer Selection Focus |
|---|---|---|---|
| Outer Case Structure | Fully rubber-covered metal skeleton | Metal outer case (partially rubber-coated) | Mounting bore accuracy: TC fits low-precision bores; TG requires high-precision bores |
| Seal Structure | Double lips (main lip + auxiliary lip) | Double lips (main lip + auxiliary lip) | Dust protection: Both provide dust resistance; TG with multi-lip design offers stronger protection |
| Pressure Resistance | Standard (≤0.05MPa) | Relatively high (for slightly high-pressure conditions) | System pressure: TG is more suitable for moderately pressurized applications |
| Temperature Resistance | Standard (NBR: -40℃~120℃; FKM: -20℃~200℃) | Standard (same as TC, depends on material) | Medium temperature: Determined by rubber material, not by model |
| Installation Compatibility | Wide compatibility, high installation tolerance | Suitable for high-precision assembly, rigid outer case | Installation process: TG requires strict bore tolerance control; TC is easier to install |
| Cost Level | Lower, cost-effective | Slightly higher, due to optimized structure and materials | Budget: TC for limited budget; TG for higher performance requirements |
| Typical Applications | Automotive gearboxes, agricultural machinery, general pumps/motors | Electric motors, compressors, high-precision hydraulic systems | Equipment precision & working conditions: TG for high-precision equipment; TC for general applications |
How to choose the right model?
1. Scenarios where TC oil seals are preferred:
General operating conditions: The equipment operates in an environment with some dust, requiring both oil and dust protection.
Installation conditions: The mounting hole precision is not high, or there is slight misalignment of the equipment housing.
Cost-sensitive: High cost-effectiveness is sought, with large-scale use and strict cost control requirements.
Common equipment: General rotating equipment such as agricultural machinery, ordinary industrial pumps, and automotive differentials.
2. Scenarios where TG oil seals are preferred:
High precision requirements: High equipment assembly precision is required, and the mounting hole and oil seal housing must fit tightly.
Enhanced pressure resistance: The system has slightly high pressure, or higher requirements are placed on the rigidity of the oil seal.
Clean environment: The internal environment of the equipment is relatively clean, with low dust protection requirements, but enhanced sealing reliability is needed.
Alternative selection: Need to replace older models of oil seals such as TC and TB, seeking higher performance and versatility.
3. Four Essential Factors for Seal Selection:
Size Matching: Shaft diameter, bore diameter, and width must strictly conform to standards (e.g., metric mm or imperial inch), ideally accurate to three decimal places.
Material Selection:
NBR (Nitrile Butadiene Rubber): Suitable for conventional mineral oils and greases, temperature resistance -40℃~120℃, moderate cost.
FKM (Fluororubber): Suitable for high-temperature and highly corrosive media, temperature resistance -20℃~200℃, higher cost.
Operating Parameters: Confirm linear velocity (≤30m/s), working pressure (≤0.05MPa), media type, and temperature to ensure compatibility with oil seal parameters.
Installation and Maintenance: Confirm mounting hole dimensions and tolerances. For TG oil seals, strict control of hole position accuracy is required to avoid improper installation leading to failure.
Q&A: Frequently Asked Questions
Can TG oil seals replace TC oil seals?
Provided that the dimensions and operating conditions are compatible, TG oil seals can generally replace TC oil seals and have advantages in pressure resistance and rigidity. However, it should be noted that TG oil seals require higher precision in mounting holes and are slightly more expensive than TC oil seals, requiring comprehensive evaluation.
What is the function of the secondary lip of the TC oil seal? Is it necessary to retain it?
The secondary lip is mainly used to prevent dust and impurities from entering, protect the main lip and shaft surface, and extend the service life of the oil seal. In clean environments with very little dust, a single-lip oil seal can be selected, but under normal operating conditions, it is recommended to retain the secondary lip to improve reliability.
How to determine if an oil seal has failed?
Common signs of failure include: oil leakage or seepage at the shaft end of the equipment; abnormal noise during operation (dry friction); wear, hardening, cracking or deformation of the oil seal lip; and impurities entering the equipment, leading to wear of bearings and other components.
Conclusion
TC oil seals are the preferred choice for their versatility and cost-effectiveness, suitable for most routine operating conditions; TG oil seals are reinforced, high-precision, and adaptable models, suitable for scenarios with higher requirements for sealing reliability and rigidity.
When selecting a seal, it is necessary to comprehensively consider installation conditions, operating parameters, and cost budget, prioritizing matching dimensions and materials to ensure a perfect fit between the oil seal and the equipment, achieving long-term stable operation.
