Analysis of oil seal failure phenomena, causes and measures

Skeleton oil seals are important components used in mechanical systems to isolate lubricating oil and grease and prevent them from leaking. They are usually installed on the shaft of mechanical parts. Through their lip-shaped structure and elastomer materials, they form a sealing barrier to prevent impurities such as iron filings, water and dust from invading the interior of the machine, thereby protecting the normal operation of mechanical equipment. The operation of oil seals is not completely reliable, and there are many factors affecting it and its surroundings. So what are the causes of problems with oil seals during operation? How to deal with it?

Oil seal failure phenomena

Oil leakage

This is the most common manifestation of oil seal failure. It can be observed that there is oil seepage at the installation site of the oil seal, which may be in the form of drops, or it may gradually form oil droplets that converge into an oil flow, resulting in oil stains around the equipment, which not only wastes oil resources, but also may pollute the surrounding environment and affect the overall cleanliness of the equipment. In severe cases, it may even cause safety hazards. For example, in specific environments such as open flames, leaked oil is prone to fires and other accidents.

Increased wear

Excessive wear occurs in the matching parts such as the oil seal lip and the sealed shaft diameter, which is intuitively manifested as roughness and damage on the oil seal lip, and the sealing surface is no longer smooth and flat. At the same time, the matching shaft diameter surface may also produce scratches and wear marks, which will further damage the sealing effect and may be accompanied by abnormal friction sounds, affecting the stability of equipment operation.

Aging, hardening or softening of rubber

Oil seals are generally made of rubber. When they fail, rubber aging may occur, which is manifested as darker color, loss of elasticity, harder and brittle texture, and easy cracking; or softening and sticky. In this way, the sealing performance of the oil seal will be greatly reduced, and it will not be able to effectively prevent oil leakage. In addition, the aged or deteriorated rubber is easy to fall off debris, which may cause oil pollution when mixed into the oil, affecting the normal operation of the entire lubrication system and related components.

Causes of oil seal failure

Installation

◆Improper installation: If inappropriate tools are used when installing the oil seal, or the operation method is incorrect, such as excessive force, the oil seal may be deformed, its original sealing structure may be damaged, and it may not fit the sealing surface, resulting in leakage and other failure problems. For example, using sharp tools to pry the oil seal can easily scratch the oil seal lip.

◆Inaccurate installation position: The oil seal is installed in a deviated position, and it is not accurately installed to the specified shaft diameter or cavity position, resulting in uneven gaps between the oil seal and the mating parts, some places are sealed too tightly, and some places are not sealed tightly, making it easy for oil to seep out from the parts that are not sealed tightly.

Use environment

◆Temperature is too high or too low: Extreme temperature environment has a great impact on the rubber material of the oil seal. In a high temperature environment, rubber is prone to accelerated aging and loss of elasticity. For example, if the oil seal around high-temperature running parts such as the engine is in a condition that exceeds its tolerance temperature range for a long time, the oil seal will soon fail; while the low temperature environment will make the rubber hard and brittle, reduce its flexibility, and easily crack, resulting in seal failure.

◆Chemical corrosion: If the oil seal is in an environment with corrosive gases, liquids, etc., such as in some chemical equipment, the oil contains corrosive components or there are corrosive gases such as acid and alkali in the surrounding air, the oil seal rubber will be corroded and lose its sealing ability.

Parts matching

◆Improper shaft diameter surface roughness: If the shaft diameter surface is too rough, it will accelerate the wear of the oil seal lip and damage the sealing surface prematurely; if the surface is too smooth, it may cause the oil seal lip and the shaft diameter to fail to form a good oil film, causing dry friction, which will also damage the oil seal and affect the sealing effect.

◆Improper size matching: The dimensional tolerance between the oil seal and the shaft diameter, cavity and other matching parts is unreasonable, the gap is too large, and the oil is easy to leak through the gap; if the gap is too small, the oil seal will be installed too tightly, resulting in excessive friction, causing the oil seal to heat up, wear and tear, and eventually fail.

Oil seal quality

◆Poor rubber material: The rubber oil seal produced by using poor quality rubber raw materials will not meet the requirements of aging resistance and wear resistance. It will also age and break quickly during normal use, and cannot guarantee long-term effective sealing.

◆Manufacturing process defects: During the production and manufacturing process of the oil seal, such as imperfect vulcanization process and inaccurate lip molding, it may cause uneven internal structure of the oil seal, bubbles and other quality problems, which will reduce the overall strength and sealing performance of the oil seal, and it is easy to fail after being put into use.

Measures analysis

Installation link

◆Standardized installation operation: Use professional installation tools, follow the installation instructions provided by the equipment manufacturer, and adopt the correct installation method, such as using appropriate tooling fixtures to slowly and steadily install the oil seal in place to avoid unnecessary damage and deformation of the oil seal.

◆Pre-installation inspection: Before installing the oil seal, carefully check the cleanliness of the installation part, the surface state of the shaft diameter, and whether the oil seal itself has defects, etc., to ensure that all aspects meet the installation conditions, and deal with the non-compliant areas in a timely manner, such as cleaning the installation cavity and repairing scratches on the shaft diameter surface.

Improvement of use environment

◆Temperature control: For equipment working in high temperature environment, heat insulation measures can be adopted, such as installing heat insulation cover, etc., to reduce the impact of external high temperature on oil seal; in low temperature environment, special oil seal materials with low temperature resistance can be considered, or the equipment can be properly preheated to make the oil seal work within the appropriate temperature range.

◆Anti-corrosion treatment: In an environment with chemical corrosion risk, it is necessary to select oil seal materials with corresponding corrosion resistance, and at the same time, the whole equipment should be well sealed to prevent external corrosive media from contacting the oil seal. The oil seal and equipment can also be cleaned regularly to remove the attached corrosive substances.

Optimization of component matching

◆Ensure shaft diameter quality: Reasonably process the shaft diameter surface to make its roughness reach the specified standard range, and ensure that the shape and position tolerances such as the cylindricality of the shaft diameter meet the requirements, providing a good matching surface for the oil seal.

◆Accurate selection and matching: According to the actual working conditions and design requirements of the equipment, accurately select oil seals with appropriate size tolerances to ensure that the matching clearance between the oil seal and the shaft diameter and cavity is reasonable, which can not only ensure good sealing, but also will not affect the oil seal life and sealing effect due to over-tightening or over-loosening.

Oil seal quality control

◆Select high-quality products: Purchase oil seals from regular and reputable suppliers, give priority to products of well-known brands that meet relevant quality standards, check the quality certification and other information of the oil seals to ensure that its rubber material is excellent and the manufacturing process is advanced. High-quality UKS seals must be purchased from authorized dealers.

◆Quality inspection: After the oil seals arrive, necessary quality inspections are carried out. Unqualified oil seal products are eliminated through appearance inspection, size measurement, and sealing performance tests of simulated working conditions to ensure the reliable quality of the installed oil seals.

In short, oil seal failure is a problem involving many factors. It requires comprehensive analysis and corresponding effective measures from multiple angles such as installation, use environment, component matching, and oil seal quality to ensure good sealing performance of the oil seal, extend its service life, and ensure the normal and stable operation of the equipment.