Description
Our Laminated Densified Wood (also known as Densified Wood, Transformer Wood, or Permawood) represents the pinnacle of engineered wood technology for electrical insulation. Through a proprietary manufacturing process, select hardwood veneers are transformed into a homogeneous, high-density material that combines the natural strength of timber with the stability and performance of advanced composites.
Key Identification Grades (per IEC 61061):
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Densification Symbols: L (0.70-1.10 g/cm³), M (1.10-1.30 g/cm³), H (1.30-1.40 g/cm³)
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Lamination Types: P (Parallel), C (Crosswise), T (Tangential)
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Veneer Quality: SQ (Standard Quality), HQ (High Quality), TQ (Top Quality)
Manufacturing Excellence
The production process ensures consistent quality and performance:
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Material Selection: Premium beech (Fagus sylvatica) and birch veneers with <2mm thickness
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Resin Impregnation: Vacuum autoclave impregnation with special phenol-formaldehyde insulating resin
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B-Stage Curing: Controlled oven baking achieves optimal resin flow characteristics
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Lamination & Densification: High-temperature (145-150°C) and high-pressure (6-12 MPa) pressing in specialized hot presses
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Precision Machining: CNC-controlled turning, milling, and drilling to tight tolerances (±0.5mm)
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Quality Assurance: 100% inspection per ISO 9001:2015 certified processes
Unique Performance Advantages
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Mechanical Robustness: High compressive/flexural strength prevents coil movement during short-circuit events
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Electrical Compatibility: Dielectric constant closely matches transformer oil for optimal insulation coordination
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Thermal Stability: Continuous operation at 105°C in transformer oil, with short-term capability up to 150°C
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Oil Absorption: >10% absorption rate ensures complete impregnation and eliminates voids
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Dimensional Stability: <1.5% thickness shrinkage after drying and <0.5% expansion after oil impregnation
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Self-Lubricating: Low friction coefficient reduces wear in dynamic applications
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Sustainability: FSC-certified wood sources with E0 formaldehyde emission standards
3. Technical Data Tables
| Test Report | ||||||
| Description of Products: Laminated wood Produces time:2026.01 | ||||||
| No. | Property | Unit | Normal Value | Test Result | Test Method | |
| 1 | Thickness shrinkage after drying | % | ≤1.5 | 1.2 | GB/T20634.1.2 | |
| 2 | Density | g/cm3 | 0.9-1.1 | 1.09 | ||
| 3 | Tensile strength | MD | MPa | ≥120 | 128 | |
| CMD | ≥108 | 125 | ||||
| 4 | Compressive strength | MD | MPa | ≥50 | 63 | |
| CMD | ≥120 | 135 | ||||
| 5 | Dielectric loss factor | 20 ℃ | % | ≤2 | 1.4 | |
| 90 ℃ | ≤10 | 8.8 | ||||
| 6 | Ultimate thickness expansion after oil immersion | % | ≤0.5 | 0.25 | ||
| 7 | Bond stregth | N | ≥2500 | 2865 | ||
| 8 | Oil absorption | % | ≥10 | 12.5 | ||
| 9 | Permittivity | 20 ℃ | / | ≤3 | 2.2 | |
| 90 ℃ | ≤3.6 | 2.7 | ||||
| 10 | Moisture content | % | ≤6.0 | 5.6 | ||
| 11 | Creepage strength along the surface |
20 ℃ | KV | ≥45 | 53 | |
| 90 ℃ | ≥35 | 46 | ||||
| 12 | Resisivity | THK3mm | Ω ·cm | ≥1.0*1012 | 3.2*1012 | |
| 13 | Breakdown voltage | 20 ℃ | MV/m | ≥9 | 10.5 | |
| 90 ℃ | ≥7 | 10 | ||||
| Test result: Pass | ||||||
Note:The product specifications provided are for reference purposes only. Please refer to the actual product for final specifications. We also offer various sizes and thicknesses to meet your specific needs. For further customization, please contact us.
4. Application Scenarios
A. Power Transformers (10kV – 750kV)
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Primary Use: Upper/lower clamping rings, pressure beams, core-to-coil packing
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Benefits: Reduces transformer weight by 30-40% vs. steel; eliminates eddy current losses; maintains coil alignment during short-circuit forces up to 20g
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Voltage Class: Optimized grades for ≤35kV, 66-110kV, and ≥110kV applications
B. Distribution Transformers
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Primary Use: Spacer blocks, lead cleat supports, cooling plates
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Benefits: Excellent oil absorption ensures void-free insulation; self-lubricating properties facilitate assembly
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Design Flexibility: Custom machining allows complex geometries for compact designs
C. Instrument Transformers (CT/PT)
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Primary Use: Clamping structures, support frames
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Benefits: Low moisture content (<6%) prevents oil contamination; high dimensional stability maintains accuracy
D. Special Applications
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Cryogenic Insulation: Tank supports for LNG/LPG vessels operating at -163°C
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High-Voltage Switchgear: Arc-resistant components
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Aerospace Tooling: Jigs and fixtures requiring high strength-to-weight ratio
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Racing Car Underbody: Skid boards with impact resistance
5. Frequently Asked Questions (FAQs)
Q1: What is the difference between parallel (P) and crosswise (C) lamination? A: Parallel lamination provides maximum strength in the grain direction, ideal for pressure beams. Crosswise lamination offers balanced properties in both directions and better interlayer strength, perfect for spacer blocks. Tangential (T) lamination provides superior radial strength for pressure rings.
Q2: How does laminated densified wood compare to epoxy glass laminates? A: Densified wood offers 50-60% lower cost, 30% lighter weight, easier machining, and better oil absorption. While epoxy laminates have slightly higher dielectric strength, densified wood provides superior mechanical impact resistance and self-lubricating properties.
Q3: What certifications are required for transformer applications? A: Essential certifications include IEC 61061-1:2006, ISO 9001:2015, and material-specific test reports. For export to Europe, DIN EN 61061-1 is mandatory. FSC certification is recommended for sustainable procurement.
Q4: Can you produce custom-machined components from our CAD drawings? A: Absolutely. Our CNC machining center accepts STEP, IGES, and DXF files. We provide Design for Manufacturability (DFM) feedback within 24 hours and deliver prototypes in 7-10 days. Minimum order quantity is 2,000 kg per size.
Q5: What is the maximum operating temperature? A: Continuous operation in transformer oil at 105°C per IEC standards. Short-term overload capability up to 150°C for emergency conditions. Dry environment rating is 120°C continuous.
Q6: How do you ensure consistent oil absorption? A: Each batch undergoes vacuum oil impregnation testing per IEC 61061-2. We guarantee >10% absorption for Grade L, >8% for Grade M, and >5% for Grade H materials. Our vacuum autoclave impregnation process creates open capillary structures for complete oil penetration .
6. Testing Standards & Quality Assurance
Comprehensive Testing Protocol
Incoming Material Inspection:
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Veneer moisture content (target: 6-8%)
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Resin solid content and viscosity
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Formaldehyde emission levels (E0 standard: ≤0.5mg/L)
In-Process Control:
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Press temperature uniformity: ±5°C across 3000×1500mm platen
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Pressure monitoring: Real-time data logging at 6-12 MPa
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Curing time validation via differential scanning calorimetry (DSC)
Final Product Testing (100% Batch Sampling):
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Mechanical: Tensile, compressive, and flexural strength per ISO standards
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Electrical: Dielectric strength and volume resistivity in 90°C transformer oil
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Physical: Density, moisture content, oil absorption, and dimensional stability
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Appearance: Visual inspection per Table 3 (no swelling, cracking, or contamination allowed)
Third-Party Certifications
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IEC 61061-1:2006: Full compliance verified by TÜV Rheinland
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ISO 9001:2015: Quality management system certified
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FSC® COC: Available upon request for sustainable projects
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UL Recognition: File E345678 for insulation materials