The continuous operation of industrial equipment relies on reliable rotary shaft seals. As a core basic component, the failure of a skeleton oil seal can lead to lubricating oil leakage, bearing seizure, and even equipment shutdown, resulting in direct production losses.

I. Material Failure-Related Faults

Rubber aging and cracking appear as radial cracks on the lip, with Shore hardness increasing by 5-10 degrees. Causes include Nitrile Butadiene Rubber (NBR) operating at high temperatures for extended periods, exposure to strong acids or alkalis, or outdoor equipment lacking ozone protection. For high-temperature conditions, switch to FKM (Viton) resistant to 200°C, coat the lip with PTFE to enhance chemical resistance, and install ozone monitoring for outdoor equipment.

Spring failure leads to a sudden increase in leakage. Disassembly reveals broken or loose springs. Causes include fatigue beyond design life, humid environments without 316L stainless steel springs, and scratches from tools during installation. Inspect via spring tension test (difference between free height and working height <15%). Improvement measures include using a dual-spring structure, zinc-nickel alloy plating (salt spray resistance ≥500h), and dedicated installation guide tools.

Skeleton deformation causes the oil seal to tilt and contact the shaft unevenly. The incidence is significantly higher in equipment such as rotary lobe pumps that frequently withstand instantaneous torque impacts. Causes include starting torque exceeding limits, bore coaxiality >0.05mm, and thermal expansion stress concentration between metal and rubber. Repair requires switching to spring steel skeleton, using a segmented structure, and controlling coaxiality to <0.02mm with a laser alignment tool.

- Bonve Pump Industry Cam-Type Twin Rotary Lobe Pump -

II. Installation Defect-Related Faults

Lip damage is the main cause of short-term leakage in newly installed oil seals, presenting as scratches or rolled edges on the lip. Causes include installation using sharp tools, shaft surface roughness Ra >0.8μm, and shaft end chamfer <15°×2mm. Standardized process: polish the shaft to Ra ≤0.4μm, apply grease, use a 10°-15° tapered guide sleeve, and press in evenly with a hydraulic press.

Incorrect installation direction causes intermittent leakage related to rotation direction. Judgment by appearance: the lip faces the medium side (oil side diameter 0.5-1mm larger), the spring groove is on the air side. It is recommended that suppliers laser-mark direction arrows.

Improper interference fit leads to early lip wear or clearance leakage. Strictly match shaft diameter: 20-50mm corresponds to 0.7-1.0mm interference, 8%-12% compression rate; 50-100mm corresponds to 1.0-1.3mm, 10%-15%; 100-150mm corresponds to 1.3-1.6mm, 12%-18%. The lip contact width should be controlled within 15%-25% of the shaft diameter.

III. Abnormal Operating Condition Faults

Lubrication failure causes the lip to carbonize and harden, with a sharp increase in friction coefficient. Causes include lubricating oil particle size >NAS Class 9, insufficient oil level, or incorrect use of high extreme-pressure gear oil. Inspect moisture content and acid value every 500 operating hours, install an oil level alarm, and select higher-grade synthetic oil for high-speed shafts.

Shaft eccentricity manifests as severe unilateral wear, with leakage increasing as speed rises. Causes include bearing radial clearance >0.1mm, coupling parallel deviation >0.05mm, and foundation settlement >0.2mm/m. Diagnose via vibration analysis. Remedial measures: replace with reduced-clearance bearings, correct foundation deviation, and perform on-site dynamic balancing.

Dry running leaves a blue oxide layer on the lip, with temperatures exceeding 150°C. Causes include excessive starts per hour, lubricating oil draining back during shutdown, and lack of an oil return line design. Solutions: use variable frequency soft start, add an oil reservoir, and use an oil seal with a 15°-20° oil return angle.

Bonve pump always adheres to the philosophy of "Wholeheartedly Making Good Rotor Pumps," committed to providing global customers with customized conveying and mixing solutions. If you have technical inquiries, selection needs, case references, or other cooperation intentions related to Bonve rotor pumps, please feel free to contact us.  

Service Hotline: 0574-87588986 13586591794  

Official Website: www.bvpumps.com  

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We look forward to working with you to drive efficiency and innovation in industrial fluid transmission with precision technology.