This paper comprehensively introduces the distinctive three-level quality control system of Liyang Propellers, which comprises three rigorous pre-furnace inspections and ten precise finished product tests. By adopting internationally advanced testing equipment and scientific technological processes, we have realized full-process quality monitoring from raw materials to finished products. Data shows that this system has increased the product qualification rate to 99.8% and extended the service life by 30%, providing customers with reliable quality assurance. The paper elaborates on the specific processes, technical standards, and equipment configurations of each test, demonstrating Liyang Propellers’ outstanding quality control capabilities.
1.Introduction
As an industry-leading propeller manufacturer, Liyang Propellers has established the most comprehensive quality control system in the sector. Our quality management system is certified to ISO 9001:2015 and strictly adheres to the standards of international classification societies such as BV and CCS. Statistics show that after the adoption of this system, the customer complaint rate has dropped to 0.2%, and the average service life of products has been extended to 8-10 years. The following is a detailed introduction to our quality control process.
2.Three-Stage Pre-Furnace Inspection System
2.1 Incoming Raw Material Inspection
Testing Equipment：
- OBLF Direct Reading Spectrometer
- Detection Accuracy：±0.001%
- Analyzable Elements: 15 types includingCu、Al、Ni、Fe
- Detection Time: 3 minutes per sample
- Universal Testing Machine
- Maximum Load：300kN
- Accuracy Class: Class5
- Testable Items: Tensile strength, yield strength, etc.
Testing Process:：
（1）Take 3 samples from each batch of raw materials
（2）Conduct spectral analysis for chemical composition
（3）Perform mechanical property testing
（4）Carry out metallographic structure observation
（5）Issue a test report
2.2 Melting Process Control
Key Equipment:：
- Real-Time Temperature Measurement SystemReal-Time Temperature Measurement System
- Temperature Measurement Range：500-1600℃
- Accuracy:：±5℃
- Sampling Frequency: 1 time per 10 seconds
- Pre-Furnace Rapid Analyzer
- Analysis Time: 3 minutes
- Detectable Elements: 5 major elements
Control Key Points:：
（1）Melting temperature is controlled within 1150±10℃
（2）Take 2 samples for analysis per heat
（3）Composition deviation ≤ 0.5%
（4）Record the complete Melting curve
2.3 Mold Quality Inspection
Inspection Items：
- Mold Dimensional Accuracy
- Measuring Equipment: Coordinate Measuring Machine (CMM)
- Number of measuring points ≥ 50 per mold
- Tolerance controlled at CT7 grade
- Molding Sand Properties
- Permeability Test：≥80
- Green CompressiveStrength：≥0.12MPa
- Moisture Content：5-5.5%
- Coating Uniformity
- Measuring Equipment: Coating Thickness Gauge
- Thickness Deviation: ≤ 0.1mm
3.Ten-Item Finished Product Testing Process
3.1 Visual Quality Inspection
Inspection Standards：
- Surface Defects
- Allowable defects: Air bubbles ≤ 1mm
- Unallowable defects: Cracks, cold shuts, etc.
- Dimensional Inspection
- Measuring tool: Professional micrometer
- Measuring accuracy: 0.02mm
- Full-size comparison against 3D model
3.4 Metallographic Structure Analysis
Testing Equipment：
- Optical Microscope
- Magnification：50-1000X
- Equipped with an image analysis system
Analysis Content：
- Grain Size: Grade 4-6
- Second Phase Distribution
- Casting Defect Evaluation
3.7 Dynamic Balance Test
Testing system：
- On-site Dynamic Balancer
- Rotational speed range：0-3000rpm
- Accuracy：01g·mm/kg
Test Procedure：
- Low-speed balancing (200rpm)
- Operating speed balancing
- Vibration value control：≤2.8mm/s
3.2 Chemical Composition Re-inspection
Test Methods：
- Sampling positions: Blade root, blade middle section, blade tip
- Testing equipment: X-ray fluorescence spectrometer (XRF spectrometer)
- Allowable deviation: ±0.3%
3.5 Dimensional Accuracy Inspection
Testing System:
- Large-scale Coordinate Measuring Machine (CMM) for Pitch
- Measuring range: Φ6000mm
- Spatial accuracy：5+L/350μm
Test Items：
- Pitch deviation：≤0.5%
- Profile tolerance：≤0.3mm
- Key fitting dimensions：IT7 grade
3.8 PT Inspection (Penetrant Testing)
Testing Equipment：
- PT-5 Penetrant Testing Agent (CCS Certified)
- Inspection scope: Entire blade
Acceptance Standards：
- Unallowable defects：
- Equivalent diameter ≥Φ3mm
- Crack-like defects
- Allowable defects：
- Single defect: ≤ Φ2mm
- Dense defects≤5/100cm²
3.3 Mechanical Performance Test
Test Items：
- Hardness Test
- Test points: 5 points per blade
- Standard value: 180-220 HB
- Testing equipment: Brinell hardness tester
- Impact Test
- Number of test pieces: 3
- Standard value: ≥50J (-20℃)
3.6 Static Balance Test
Testing Equipment：
- Static Balancing Stand
- Maximum load capacity：20T
- Sensitivity：01kg·m
Test Standards：
- Allowable unbalance: ≤0.5% × weight
- Calibration method: Counterweight welding
4.Quality Traceability System
4.1 Unique Product Code
Coding Rules：
- Year (2 digits)
- Material code (1 digit)
- Serial number (5 digits)
- Inspector code (2 digits)
4.2 Data Management System
System Functions：
- Full-process data recording
- Quality trend analysis
- Automatic abnormal alarm
- Automatic report generation
5.Conclusion
By implementing three rigorous pre-furnace inspections and ten finished product tests, Liyang Propellers has established an industry-leading quality control system. This system boasts the following advantages:
- Comprehensive coverage of test items
- Advanced equipment with high precision
- Rigorous and standardized standards
- Traceable data
Our Quality Commitments：
- Ex-factory qualification rate of 99.8%
- 8-year service life guarantee
- Provision of complete inspection reports
- 24-hour quality response
Choosing Liyang Propellers means you are selecting not just a product, but a trustworthy quality assurance system.
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