Lock-up Failure Analysis: From "Sudden Cardiac Arrest" to Prevention

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Lock-up Failure Analysis: From "Sudden Cardiac Arrest" to Prevention

Release time:

2025-07-28

Lock-up Failure Analysis: From "Sudden Cardiac Arrest" to Prevention

CHANUN AIR COMPRESSOR

Rotor Lock-up
The compressor rotor acts as the heart of the equipment. Once a lock-up occurs, the entire system shuts down instantly.

This failure stems from abnormal friction or jamming between male-female rotors or between the rotor and cylinder, triggering a vicious cycle of "friction → temperature rise → seizure."

Early warnings include abnormal noise, increased vibration, and sudden discharge temperature spikes. If unaddressed, consequences escalate severely: motor overload may burn coils, rotor teeth can shear off, and catastrophic explosions may occur.

Statistics show that lock-up repairs cost over one-third of a new machine’s price—far exceeding routine maintenance. Post-repair performance rarely fully recovers.

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Failure Causes
1. Total Lubrication System Failure

Oil volume/quality issues: Low oil level or clogged lines cause metal-on-metal friction; oxidized, emulsified, or contaminated oil breaks down the oil film. Oil viscosity plummets above 80°C.

Case: A plant restarted a compressor after transport without refilling oil, causing instant rotor seizure. Resolution: 5 hours of disassembly, soaking, and cleaning.

2. Foreign Object Ingress & High-Temperature Coking

Failed air filters allow dust or welding slag into the compression chamber, jamming micron-level rotor clearances.
More insidiously, prolonged operation >75°C cracks lubricant into carbides that accumulate on rotors, narrowing gaps. Tests show just 0.1mm of coking reduces clearance by 40%.

3. Assembly Deviation & Bearing Failure

Worn bearings cause excessive radial/axial rotor displacement, leading to uneven wear.

Case: Discharge-end bearing cage fracture scattered rollers, melting the rotor to the cylinder.
Improper male-female rotor side clearance (typically 0.03–0.05mm) or >0.01mm shaft misalignment during assembly induces localized friction heat.

4. Operational & Environmental Triggers
Pre-start failure to barring, chronic overload (excessive compression ratios), and poor ventilation (raising ambient temperature) contribute to 34% of lock-ups.

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Prevention & Mitigation
Preventive Maintenance

Lubrication management: Weekly oil checks; change specified oil every 2,000 hrs; clean oil coolers regularly.
Clearance monitoring: Every 8,000 hrs, inspect rotor gaps/bearing play; measure axial float with dial indicator (<0.01mm).
Contamination control: Clean air filters daily; install 100-mesh brass screens at oil return ports.
Standardized operation: Bar rotors 3–5 turns pre-start; install redundant temperature/pressure alarms.

Post-Lock-up Response

Cut power immediately! Never force barring or disassembly.
Expert inspection: Verify oil condition first; then disassemble cylinder to inspect rotor scoring/coking.
Post-repair calibration: Validate shaft alignment with laser alignment tool (deviation ≤0.05mm).

💸 A costly lesson: One plant’s failed hydraulic disassembly attempt destroyed the rotor assembly, costing over ¥200,000.

Key Translation Notes:

Technical Terminology
- 抱死 (bàosǐ) → "Lock-up" (industry standard for mechanical seizure)
- 阴阳转子 (yīnyáng zhuǎnzǐ) → "Male-female rotors"
- 结焦 (jiéjiāo) → "Coking" (thermal degradation of oil)
- 盘车 (pánchē) → "Barring" (manual rotation check)
Precision Metrics Retention
- All measurements (0.01mm, 80°C, 2000hrs) preserved verbatim for technical accuracy.
Case Study Adaptation
- Passive voice used in examples ("A plant restarted...") for objectivity.
- Action verbs ("disassembly, soaking, and cleaning") clarify procedures.
Safety Emphasis
- "Cut power immediately!" retains urgency of original warning .
Cultural Adaptation
- (blood-and-tears lesson) → "costly lesson" (maintains gravity without over-sensationalizing).