NP329 Bleached Linen Melamine Laminate Sheet
NP329 Bleached Linen Melamine Laminate Sheet is a bleached linen composite combined with a melamine resin system, providing better arc resistance than NP320E and resistance to ammonia-based refrigerants. The material is a hard, durable laminate that should be heated to punch but machines very well with standard machining equipment, delivering an arc resistance of 135 seconds, a comparative tracking index of 200 V, and a compressive strength of 44,000 psi flatwise. No NEMA grade is assigned to this material. Not UL Listed.
Key Properties
- Flexural Strength, Condition A LW / CW: 32,200 / 25,500 psi (222.0) / (175.8) MPa (ASTM D790)
- Compressive Strength, Condition A Flatwise: 44,000 psi (303.4) MPa (ASTM D695)
- Tensile Strength, Condition A LW / CW: 24,100 / 13,700 psi (166.2) / (94.5) MPa (ASTM D638)
- Arc Resistance, Condition A: 135 sec (ASTM D495)
- Comparative Tracking Index: 200 V (ASTM D3638)
- Temperature Index — Mechanical: 130°C (UL Bulletin 746b)
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- Specifications
- Applications
- General Info
- FAQs
Physical Properties
| Property | Value | Test Method |
| Specific Gravity | 1.47 | ASTM D792 |
| Rockwell Hardness (0.250″ Build-up) | 95 M Scale | ASTM D785 |
| Moisture Absorption, Condition D₁-24/23 | 3.60% | ASTM D570 |
| Flexural Strength, Condition A LW / CW | 32,200 / 25,500 psi (222.0) / (175.8) MPa | ASTM D790 |
| Flexural Modulus, Condition A LW / CW | 1,700 / 1,100 kpsi (11.7) / (7.6) GPa | ASTM D790 |
| Tensile Strength, Condition A LW / CW | 24,100 / 13,700 psi (166.2) / (94.5) MPa | ASTM D638 |
| Tensile Modulus, Condition A LW / CW | 2,600 / 1,500 kpsi (17.9) / (10.3) GPa | — |
| Izod Impact Strength, Condition E-48/50 LW / CW | 1.80 / 1.30 ft-lb/in (0.96) / (0.69) J/cm | ASTM D256 |
| Compressive Strength, Condition A Flatwise | 44,000 psi (303.4) MPa | ASTM D695 |
| Bonding Strength, Condition A | 1,600 lb (725.7) kg | ASTM D229 |
| Bonding Strength, Condition D-48/50 | 1,400 lb (635.0) kg | ASTM D229 |
| Shear Strength, Condition A Perpendicular | 26,000 psi (179.3) MPa | ASTM D732 |
Thermal Properties
| Property | Value | Test Method |
| Temperature Index — Mechanical | 130°C | UL Bulletin 746b |
| Coefficient of Thermal Expansion, X-axis / Y-axis | 18.0 / 19.0 (“/”/°C × 10⁻⁶) | IPC-TM 650-2.4.24 |
| Flammability Rating, Condition A | HB | UL Bulletin 94 |
Electrical Properties
| Property | Value | Test Method |
| Dissipation Factor @ 1 MHz, Condition A | 0.070 | ASTM D150 |
| Dissipation Factor @ 1 MHz, Condition D-24/23 | 0.090 | ASTM D150 |
| Relative Permittivity @ 1 MHz, Condition A | 7.20 | ASTM D150 |
| Relative Permittivity @ 1 MHz, Condition D-24/23 | 8.60 | ASTM D150 |
| Breakdown Voltage, Condition A | 65 kVolts | ASTM D149 |
| Breakdown Voltage, Condition D-48/50 | 9 kVolts | ASTM D149 |
| Electric Strength, Condition A | 380 Volts/mil (149.6) kV/cm | ASTM D149 |
| Electric Strength, Condition D-48/50 | 100 Volts/mil (39.4) kV/cm | ASTM D149 |
| Arc Resistance, Condition A | 135 sec | ASTM D495 |
| Comparative Tracking Index | 200 V | ASTM D3638 |
- Electrical insulation components requiring improved arc resistance vs. linen phenolic grades
- Insulation components in ammonia-based refrigerant systems
- Precision-machined melamine linen insulation parts requiring fine surface finish
- Heated-punch fabricated insulation components
- General electrical and mechanical insulation applications where melamine resin chemistry is preferred
Common industries: Electrical Equipment Manufacturing, Refrigeration and HVAC, Industrial Manufacturing, Precision Machining, General Engineering.
NP329 Bleached Linen Melamine Laminate Sheet is a specialty melamine resin laminate constructed from bleached linen fabric — a distinct material family from the phenolic linen grades — designed specifically for applications requiring improved arc resistance and resistance to ammonia-based refrigerants compared to standard linen phenolic grades such as NP320E. The melamine resin system delivers an arc resistance of 135 seconds vs.
15 seconds for NP320E, and a comparative tracking index of 200 V. This combination of superior arc and tracking performance makes NP329 the preferred linen-based laminate for electrical insulation applications where arc fault resistance or exposure to ammonia refrigerants is a design consideration.
The material delivers a flexural strength of 32,200 / 25,500 psi (LW/CW), a compressive strength of 44,000 psi flatwise, and a tensile strength of 24,100 / 13,700 psi (LW/CW). The tensile modulus is 2,600 / 1,500 kpsi (LW/CW). Breakdown voltage is 65 kV (Condition A) and electric strength is 380 Volts/mil (Condition A). Both bonding strength conditions are listed: 1,600 lb (Condition A) and 1,400 lb (Condition D-48/50).
The mechanical temperature index is 130°C; the electrical temperature index value is not listed on the manufacturer’s TDS. Moisture absorption is 3.60% and flammability is rated HB per UL 94. NP329 is hard enough to require heating for punch operations, but machines very well with standard machining equipment.
What differentiates NP329 Bleached Linen Melamine Laminate Sheet from NP320E (linen phenolic, Grade LE)?
NP329 uses a melamine resin system rather than a phenolic resin, which delivers significantly better arc resistance — 135 seconds vs. 15 seconds for NP320E — and a comparative tracking index of 200 V vs. 170 V. NP329 is also specifically resistant to ammonia-based refrigerants, which NP320E does not address. The trade-off is that NP329 carries no NEMA grade designation and no compliance specifications, while NP320E is certifiable to NEMA Grade LE, MIL-I-24768/13 FBE, and other specifications. For applications where arc resistance or ammonia resistance is the primary driver and specification compliance is not required, NP329 is the superior choice.
Why does arc resistance matter when selecting a linen laminate for electrical insulation?
Arc resistance measures how long a material surface withstands a high-voltage electrical arc before carbonizing and forming a conductive tracking path. In switchgear, contactors, and electrical enclosures where arc fault events can occur, a higher arc resistance means the insulation surface resists the formation of conductive carbon deposits that would cause further arcing and potential failure. NP329's melamine resin system achieves 135 seconds vs. 15 seconds for standard linen phenolic grades — a nine-fold improvement that meaningfully extends the insulation's functional life in arc-prone environments.
What is the mechanical temperature index for NP329 Bleached Linen Melamine Laminate Sheet?
The mechanical temperature index is 130°C, as listed on the Technical Datasheet. The electrical temperature index value is not listed on the manufacturer's TDS.
Does NP329 Bleached Linen Melamine Laminate Sheet carry any NEMA or compliance specifications?
No. NP329 carries no NEMA grade designation and no compliance specifications are listed on the manufacturer's TDS. Applications requiring a NEMA-designated or specification-compliant linen laminate should specify NP320 (NEMA Grade L) or NP320E (NEMA Grade LE).
How should NP329 Bleached Linen Melamine Laminate Sheet be specified?
Specify grade (NP329 Bleached Linen Melamine Laminate Sheet), thickness, fabrication method (machined or heated punch), dimensional tolerances, and finished format. Note that no NEMA grade or compliance specification applies to this material per the manufacturer's TDS.
