Key Standards for Judging Skeleton Oil Seal Quality

When assessing the quality of skeleton oil seals, two main aspects should be considered: appearance and performance. Below are commonly accepted standards.

Appearance Inspection

Surface Quality: A high-quality oil seal should have a smooth, even surface without burrs, cracks, bubbles, or embedded impurities. The rubber must show uniform color, the metal frame should be free of rust, and the sealing lip (edge) must be sharp, even, and without notches.

Dimensional Accuracy: Using a vernier caliper, the tolerance for inner and outer diameters is typically within ±0.1 mm. The lip interference fit should ideally be 0.1–0.3 mm. The seal face should clearly display the dimensions (shaft diameter × outer diameter × height), manufacturer name, and trademark.

Structural Integrity: Rubber must bond tightly with the reinforcement ring, with no looseness or misalignment. The inner and outer surfaces should not expose metal. For seals with springs, the spring must be rust-free, undeformed, and firmly seated in its groove.

Performance Testing

Oil Resistance: Immerse the seal in transmission oil No. 25 at 70 ± 5 °C for 24 hours. The weight change should remain within −3% to +5%. Alternatively, immerse in a mixture of 75% gasoline No. 120 and 25% benzene at 20 ± 5 °C for 24 hours; the weight change should not exceed +20%.

High-Temperature Resistance: The seal material must withstand a wide range of operating temperatures. A premium oil seal should maintain sealing properties under both high and low temperatures without aging, hardening, or softening.

Sealing Performance: Through installation testing, verify that the seal prevents oil leakage during shaft rotation and blocks external contaminants. Standardized pressure and temperature tests are typically used to confirm sealing effectiveness.

Physical Properties: Measure hardness (tolerance ±5 Shore A), tensile and compressive strength, and friction/aging resistance using professional testing instruments.

By checking both appearance and performance against these standards, you can quickly determine whether a skeleton oil seal meets quality requirements.