Introduction to Radial Shaft Seals

Radial shaft seals (also known as oil seals) are precision sealing components consisting of a metal casing and a rubber sealing lip. They are primarily used for sealing rotating shafts to prevent lubricant leakage and exclude contaminants.

 

Core Characteristics

Characteristic	Description	Advantages
High Efficiency Sealing	Lip design generates radial tightening force	Achieves dynamic rotary sealing
Dual Function	Prevents leakage and excludes contaminants	Protects bearings and lubrication systems
Compact Structure	Integrated metal casing reinforcement	Easy installation, good stability
Media Resistance	Multiple rubber material options	Adapts to different lubricants and environments
Long Service Life	Optimized lip design reduces wear	Extends equipment maintenance intervals

 

Structural Components

Component	Material	Function
Metal Casing	Low carbon steel plate	Provides structural strength and installation stability
Sealing Lip	NBR, FKM, etc	Main sealing function, generates radial force
Spring	Stainless steel wire	Compensates for lip wear, maintains pressure
Dust Lip	Same as sealing lip	Prevents external dust ingress (double lip type)

 

 Type Classification

 

Type	Characteristics	Applications
Single Lip Type	Only main sealing lip	Clean environments, leakage prevention only
Double Lip Type	Main seal lip + dust lip	Dusty environments, dual protection needed
Outer Casing Type	Exposed metal casing	Heavy duty applications, better installation stability
Inner Casing Type	Embedded metal casing	Standard applications, most common type
Hydrodynamic Type	Lip with return grooves	High speed applications, improved sealing effect

 

Performance Parameters Table

Performance Indicator	Standard Type	High Speed Type	Pressure Resistant Type	Test Standard
Suitable Speed	≤15m/s	≤25m/s	≤8m/s	ISO 6194
Pressure Resistance	≤0.05MPa	≤0.03MPa	≤0.3MPa	ISO 16589
Temperature Range	-40~100℃	-40~120℃	-40~150℃	ASTM D2000
Shaft Diameter Range	3~500mm	5~300mm	10~200mm	ISO 3601
Service Life	2000~5000h	1000~3000h	3000~8000h	SAE J1960

 

 Selection Guide

1. Operating Condition Analysis:

   · Shaft diameter and speed

   · Media type and temperature

   · Environmental conditions (dust, humidity, etc.)

2. Material Selection:

   · NBR: General purpose, resistant to petroleum-based oils

   · FKM: High temperature and chemical resistance

   · ACM: Resistant to extreme pressure additive oils

   · SIL: Wide temperature range

3. Size Determination:

   · Select specification according to shaft diameter

   · Consider installation space

   · Confirm tolerance fit

 

 Installation Requirements

1. Pre-installation Preparation:

   · Check shaft surface (hardness ≥HRC45, Ra=0.2-0.8μm)

   · Remove burrs and sharp edges

   · Clean installation area

2. Installation Methods:

   · Use special installation tools

   · Lubricate lip with grease

   · Avoid impact and傾斜 installation

3. Post-installation Inspection:

   · Confirm proper installation

   · Check for lip rolling

   · Test run for leakage check

 

 Common Failure Modes and Countermeasures

Failure Phenomenon	Possible Causes	Solutions
Leakage	Lip wear, spring detachment	Replace seal, check shaft wear
Lip Burning	Poor lubrication, overheating	Improve lubrication, reduce temperature
Aging Cracking	Media incompatibility, high temperature	Change material, reduce temperature
Installation Damage	Improper installation, unsuitable tools	Use special tools, standardize installation

Application Fields

1. Automotive Industry: Engines, transmissions, axles

2. Construction Machinery: Hydraulic systems, slewing bearings

3. Home Appliances: Washing machines, AC compressors

4. Industrial Pumps/Valves: Various rotary pumps, valves

5. Aerospace: Engines, hydraulic systems

Maintenance Recommendations

1. Regular Inspection:

   · Check leakage situation

   · Observe lip condition

   · Monitor temperature changes

2. Preventive Replacement:

   · Plan replacement based on operating hours

   · Mandatory replacement during overhaul

   · Timely replacement when abnormalities are found

3. Storage Requirements:

   · Avoid direct sunlight

   · Keep away from heat sources

   · Prevent deformation during storage

 

Radial shaft seals, as a mature rotating shaft sealing solution, can provide reliable sealing protection for rotating equipment through proper selection, correct installation, and regular maintenance. Understanding their structural characteristics, performance parameters, and failure modes is key to ensuring sealing effectiveness and extending service life.