This document presents SEAMAC’s distinctive three-tier quality management system for marine propellers. The system comprises three rigorous pre-pour inspections and ten precision final-product tests. By employing internationally advanced inspection equipment and scientifically established procedures, we achieve full-process quality monitoring from raw material to finished propellers. Data shows that the system raises the acceptance rate to 99.8 % and extends service life by 30 %, delivering reliable quality assurance to customers. The article details the specific workflows, technical standards and equipment configurations for every test, demonstrating SEAMAC’s outstanding quality-control capability.
1. Introduction
As a leading propeller manufacturer, SEAMAC has built the industry’s most comprehensive quality-control system. Our quality-management system is certified as ISO 9001:2015 and strictly follows the standards of major classification societies such as BV and CCS. Statistics indicate that after adopting this system, customer complaints have fallen to 0.2 % and average product life has increased to 8–10 years. The quality-control process is described below.
2. Three-Step Pre-Pour Inspection System
2.1 Raw-Material Incoming Inspection
Inspection equipment：
- OBLF spark-atomic-emission spectrometer
- Accuracy: ±0.001 %
- Elements analyzed: 15, including Cu, Al, Ni, Fe
- Test time: 3 min/sample
- Universal materials testing machine
- Maximum load：300kN
- Accuracy class：5
- Tests: tensile strength, yield strength, etc.
Procedure：
（1）Take three samples from each batch
（2）Perform chemical analysis by spectrometry
（3）Conduct mechanical-property tests
（4）Examine metallographic structure
（5）Issue an inspection report
2.2 Melt-Process Control
Melt-Process Control：
- Real-time temperature system
- Range: 500-1600℃
- Accuracy：±5℃
- Sampling rate: 1 scan/10 s
- Furnace-side rapid analyzer
- Analysis time: 3 min
- Elements checked: 5 major elements
Control points：
（1）Maintain melt temperature at 1150±10℃
（2）Take two samples per heat for analysis
（3）Allowable composition deviation ≤0.5%
（4）Record complete melt-cooling curve
2.3 Mold-Quality Check
Mold-Quality Check：
- Mold dimensional accuracy
- Equipment: 3-D coordinate measuring machine (CMM)
- ≥50 measuring points per mold
- Tolerance class CT7
- Molding-sand properties
- Permeability test：≥80
- Wet compressive strength：≥0.12MPa
- Moisture content：5-5.5%
- Coating uniformity
- Coating thicknessgauge
- Thickness deviation≤0.1mm
3. Ten-Step Final-Product Inspection
3.1 Visual Inspection
Standards：
- Surface defects
- Allowed: pores ≤1mm
- Not allowed: cracks, cold shuts, etc.
- Dimensional check
- Tool: precision micrometer
- Accuracy：02mm
- Full-size comparison with 3-D model
3.2 Chemical-Composition Re-check
Method：
- Sampling positions: blade root, mid-span, tip
- Equipment: X-ray fluorescence spectrometer
- Allowable deviation: ±0.3 %
3.3 Mechanical-Property Tests
Tests：
- Hardness test
- Points: 5 per blade
- Standard: 180-220HB
- Equipment: Brinell hardness tester
- Impact test
- Specimens: 3
- Standard:：≥50J（-20℃）
3.4 Metallographic Analysis
Equipment：
- Optical microscope
- Factor of magnification：50-1000X
- with an image-analysis system
Analysis content：
- Grain size: 4–6
- Secondary-phase distribution
- Casting-defect assessment
3.5 Dimensional-Accuracy Inspection
System：
- Large-scale CMM propeller pitch gauge
- Measuring range：Φ6000mm
- Spatial accuracy：5+L/350μm
Inspection items：
- Pitch deviation：≤0.5%
- Profile tolerance：≤0.3mm
- Critical mating dimensions： IT7grade
3.6 Static-Balance Test
Equipment：
- Static-balance stand
- Maximum load：20T
- Sensitivity：01kg·m
Standard：
- Allowable unbalance: ≤5 %×weight
- Correction: balance weights welded on
3.7 Dynamic-Balance Test
System：
- Field dynamic-balance instrument
- Speed range：0-3000rpm
- Accuracy：01g·mm/kg
Procedure：
- Low-speed balance（200rpm）
- Service-speed balance
- Vibration limit：≤2.8mm/s
3.8 PT (Penetrant-Testing) Inspection
Equipment：
- CCS-approved PT-5 penetrant kit
- Full-blade coverage
Acceptance criteria：
- Disallowed defects：
- cracks and indications≥Φ3mm
- Crack-typedefect
- Allowed defects：
- single≤Φ2mm
- clustered≤5per 100cm²
4. Quality Traceability System
4.1 Unique Product Code
Encoding rules：
- Year (2 digits)
- Material code (1 digit)
- Serial number (5 digits)
- Inspector code (2 digits)
4.2 Data-Management System
Functions：
- End-to-end data logging
- Quality-trend analysis
- Automatic abnormality alerts
- Report auto-generation
5. Conclusion
Through rigorous three-step pre-pour inspections and ten-step final-product tests, SEAMAC has built an industry-leading quality-control system featuring：
- Comprehensive test coverage
- Advanced, high-precision equipment
- Strict, standardized criteria
- Full data traceability
Our quality commitment：
- 8 % ex-works acceptance rate
- 8-year service-life guarantee
- Complete inspection report supplied
- 24-hour quality response
Choosing SEAMAC propellers means choosing not only a product but a trustworthy quality-assurance system.
