The metal-cased oil seal is a typical representative of oil seals. In everyday language, the term "oil seal" usually refers to this type. It is a rotary shaft lip seal primarily used to separate lubricated parts in a transmission from the external environment, preventing leakage of lubricating oil.

The word "cased" (or "skeleton") aptly describes its structural feature – the metal case acts like the rebar in reinforced concrete, providing reinforcement so that the seal maintains its shape and tension.

The sealing principle can be summarised as a "controlled leakage" oil film seal:

1,Oil film formation – a very thin layer of lubricating oil is maintained between the seal lip and the rotating shaft.

2,Surface tension effect – at the interface with air, the oil film forms a meniscus due to surface tension, preventing the working medium from leaking out.

3,Dynamic balance – sealing effectiveness depends on oil film thickness: too thick leads to leakage, too thin causes dry friction and premature wear.
Therefore, it is essential to apply lubricating oil to the seal during

installation and ensure the seal is perpendicular to the shaft centreline. Ideally, a slight seepage of lubricant occurs during operation, forming a stable oil film at the sealing face.

Metal-cased oil seals are widely used for sealing various rotating shafts:

Automotive / Motorcycles – crankshafts, camshafts, gearboxes, differentials, shock absorbers, engines, axles, front and rear wheels.
Industrial equipment – gearboxes, bearing housings, reducers, blowers, air compressors, pumps, motors.
Wind power – wind turbine gearbox seals.
Their two main functions are:

Preventing lubricating oil leakage.
Preventing ingress of contaminants such as sand, dust, moisture, etc.
Speed matching – use high-speed seals for high-speed shafts and low-speed seals for low-speed shafts; do not interchange.
Temperature compatibility – choose fluoroelastomer or silicone rubber for high temperatures; choose cold-resistant materials for low temperatures.
Pressure limitation – ordinary oil seals have poor pressure resistance (approx. 0.5 bar); for higher pressures, use a pressure-supporting backup ring.
Eccentricity control – excessive runout or misalignment will impair sealing performance.
Shaft surface finish – recommended Ra 0.2–0.8 μm; higher smoothness extends service life.
Shaft hardness – recommended ≥ HRC 45 to prevent axial scoring.
Installation orientation – ensure the seal is perpendicular to the shaft centreline.
Pre-lubrication – apply a small amount of lubricating oil to the lip before installation.

Q 1. What's the payment term?
A: We accept T/T 50% advance ,   50% balance before booking shipping date.

Q 3. What is your standard packing?
A: All the goods will be packed by carton box and loaded with pallets. Special packing method can be accepted when needed.

Q 4. Could you please tell us the month capacity of your products ?
A: It depends on which model, we produce more than 500 tons rubber materials per month.

Q 5. what kind of certificates you have ?
A1: We have been ISO9001:2015 and ISO14001:2004 certified by SGS since 2015.
A2: We have various rubber compounds approved by ROHS and REACH.

Q6: How to check the quality of the bulk order?
A1: We provide preproduction samples before mass production for all customers if needed.
A2: We accept third party inspection such as TUV, INTERTEK, BV, etc.

Q 7: Do you use any international standards for the rubber products?
A: Yes, we mainly use GB/T3452.1-2005 standard to define the quality of the rubber materials.

Q8: What materials are available to produce from your side?
A: NBR, EPDM, SILICONE, FPM(FKM), PTFE,POM,PU,NEOPRENE(CR), NR, IIR, SBR, ACM, AEM, Fluorosilicone(FVMQ), FFKM, Liquid Silicone, Sponge, etc.

Q9: Do you provide maintenance on tooling?
A: We maintain all tooling and will replace as needed.

Q10: How many empolyees you have?
A:We have 25 empolyees at time of December 2024.

Customer can choose 4ways for get the goods.

NINGBO PALT IMPORT AND EXPORT CO.,LTD (The factory name is Huan Ling Sealing  )the products including the O-rings, Flat washer, rubber rings, ED-Ring,Bonded seal,PTFE rings, O-ring Kit,rubber ball, Y-rings,Rubber Strip,Piston U-seal,Rod U-seal,Glyd-Ring,Sitefeng seals, v-shaped rings, X-rings and other various non-standard rubber.In addition,The main material can be NBR, EPDM, FKM, , AFLAS, CR, Butyl, HNBR, SILICON, FFKM, PU or approved by  etc.

Huan Ling Sealing has the product is made of imported raw materials, quality excellent, the company products have been exported to Europe and the United States, the feedback is good, is a broad seal users trustworthy company.

Huan Ling Sealing established in 2011. Huan Ling Sealing is a professional rubber products manufacturer .Business involves the engineering machinery, plastic machinery, hydraulic press, compressor, die-casting machine, ceramic machinery, port machinery, metallurgical machinery, steel, steamboat manufacturing, coal mine machinery, chemical machinery, light industry machinery, mining machinery and machine tools, and other fields and industries.