ISO Test Data Comparison · September 3, 2026 · Juhai R&D Center
PA6 GF30 vs PA66 GF30 — Side-by-Side ISO Test Data Comparison
You know PA6 and PA66 are different nylons — but when both are reinforced with 30% glass fiber, the practical gaps in strength, heat resistance and cost become measurable. This article compares Juhai's premium PA6 BFE01 (GF30) against PA66 BFE04 (GF30) using actual ISO-standard test data from our R&D laboratory. No generic spec sheet estimates — real numbers from real pellets.
Table of Contents
- 1. Full Side-by-Side Property Table
- 2. Mechanical Performance: Strength, Stiffness and Impact
- 3. Thermal Performance: HDT, Melting Point and Continuous Use
- 4. Dimensional Stability, Shrinkage & Moisture
- 5. Injection Molding Parameters Compared
- 6. Cost-Performance Analysis
- 7. Application Recommendations: Which to Use When
- 8. Frequently Asked Questions (FAQ)
1. Full Side-by-Side Property Table
All values below are from Juhai Plastics in-house testing per ISO standards, performed on freshly compounded production lots of PA6 BFE01 (Premium 30% GF PA6) and PA66 BFE04 (Premium 30% GF PA66). Test conditions follow ISO standards strictly — no idealized lab data.
| Property | Test Standard | PA6 GF30 (BFE01) | PA66 GF30 (BFE04) | Difference |
|---|---|---|---|---|
| Tensile Strength | ISO 527 | 162 MPa | 190 MPa | PA66 +17% |
| Tensile Modulus | ISO 527 | 8,500 MPa | 9,200 MPa | PA66 +8% |
| Elongation at Break | ISO 527 | 3.2% | 3.0% | PA6 +7% |
| Flexural Strength | ISO 178 | 245 MPa | 280 MPa | PA66 +14% |
| Flexural Modulus | ISO 178 | 7,400 MPa | 8,100 MPa | PA66 +9% |
| Notched Izod Impact, 23°C | ISO 180/1A | 17 kJ/m² | 18 kJ/m² | PA66 +6% |
| Unnotched Izod, 23°C | ISO 180/1U | 78 kJ/m² | 85 kJ/m² | PA66 +9% |
| Rockwell Hardness | R Scale | R 114 | R 118 | PA66 +4 |
| HDT @1.82 MPa (critical) | ISO 75/Af | 198°C | 250°C | PA66 +52°C |
| HDT @0.45 MPa | ISO 75/Bf | 211°C | 265°C | PA66 +54°C |
| Vicat Softening Temp | B/50 | 215°C | 252°C | PA66 +37°C |
| Melting Point (DSC Peak) | ISO 3146 | 222°C | 260°C | PA66 +38°C |
| Density | ISO 1183 | 1.35 g/cm³ | 1.38 g/cm³ | PA66 +2% |
| Mold Shrinkage — Flow | ISO 294-4 | 0.33% | 0.30% | PA6 +0.03% |
| Mold Shrinkage — Cross | ISO 294-4 | 0.90% | 0.85% | PA6 +0.05% |
| Water Absorption (24h) | ISO 62 | 0.95% | 0.60% | PA6 +58% |
| Continuous Use Temp | UL 746B | 120°C | 140°C long-term / 170°C short-term | PA66 +20°C |
2. Mechanical Performance: Strength, Stiffness and Impact
At 30% glass fiber loading, PA66 GF30 is consistently 8–17% stronger and stiffer than PA6 GF30 across all ISO-standard tensile, flexural and hardness measurements. This is the most predictable difference in the comparison.
Tensile and Flexural Strength
The 17% tensile gap (162 vs 190 MPa) and 14% flexural gap (245 vs 280 MPa) come from PA66's denser inter-molecular hydrogen bonding. The hexamethylenediamine-adipic acid backbone packs more tightly than PA6's caprolactam chain, giving stiffer fiber-polymer interfaces and more efficient stress transfer from the glass fibers.
Practical impact: For structural parts where 162 MPa is sufficient, PA6 GF30 is the budget winner. But if you're designing to a safety margin of 1.5x on a 170 MPa yield requirement, PA6 GF30 can't reach it — only PA66 GF30 gives you that margin.
Impact Resistance
The impact difference is much smaller than the tensile gap. Notched Izod only differs by 6% (17 vs 18 kJ/m²), and both grades show ductile break mode at 23°C. Unnotched Izod follows a similar pattern (78 vs 85 kJ/m²). This means that for clips, snap fits and housings where impact matters more than raw strength, PA6 GF30 delivers nearly identical performance to PA66 GF30.
3. Thermal Performance: HDT, Melting Point and Continuous Use
This is where PA66 GF30 delivers its most dramatic advantage. The 52°C HDT gap at 1.82 MPa (198°C vs 250°C) is the single most important reason to pay the PA66 premium.
HDT Comparison
Heat Deflection Temperature measures the temperature at which a beam deflects 0.25 mm under a specified load. PA66 GF30 holds its shape at 52°C higher than PA6 GF30 under the 1.82 MPa load that matters for structural brackets.
Practical impact: If your part operates continuously above 150°C — a bracket under a hot engine, a connector near a power transistor, or a housing for a high-power LED driver — PA6 GF30 may soften and deform over time. PA66 GF30's 250°C HDT gives it reliable long-term stability at 180°C.
Continuous Use Temperature
PA6 GF30 (BFE01) has a UL 746B continuous use temperature of 120°C. PA66 GF30 (BFE04) is rated 140°C long-term / 170°C short-term for electrical applications. For general engineering use where UL certification is not required, PA6 GF30 has been validated in-house at 140°C continuous for non-safety-critical parts (10,000-hour heat-aging testing with < 10% tensile retention loss).
4. Dimensional Stability, Shrinkage & Moisture
Mold Shrinkage
Both grades have low shrinkage thanks to 30% glass fiber reinforcement, but PA6 GF30 has slightly higher shrinkage in both directions:
- Flow direction: PA6 GF30 0.33% vs PA66 GF30 0.30%
- Cross direction: PA6 GF30 0.90% vs PA66 GF30 0.85%
The cross-direction shrinkage is 2.7x higher than flow direction in both grades — this fiber-induced anisotropy affects warpage, especially on large flat parts. PA66 GF30's slightly more balanced shrinkage contributes to better flatness on wide housings.
Water Absorption
PA6 GF30 absorbs 58% more moisture than PA66 GF30 (0.95% vs 0.60% after 24-hour immersion per ISO 62). In practice, this means PA6 GF30 parts will swell slightly more in high-humidity environments — roughly 0.05–0.10% dimensional change at equilibrium moisture content.
However: both grades require the same pre-drying discipline. PA6 GF30 must be dried to moisture < 0.08% at 80°C for 4 hours; PA66 GF30 to moisture < 0.06% at 90°C for 4 hours. Neither can be molded "as-is" — skipping drying causes splay, silver streaks and reduced strength.
5. Injection Molding Parameters Compared
| Parameter | PA6 GF30 (BFE01) | PA66 GF30 (BFE04) |
|---|---|---|
| Melt Temperature Range | 250 – 275°C | 270 – 295°C |
| Mold Temperature Range | 70 – 100°C | 70 – 100°C |
| Class-A Surface Mold Temp | 85 – 100°C | 90 – 110°C (recommended) |
| Pre-Drying | 80°C × 4h, < 0.08% | 90°C × 4h, < 0.06% |
| MVR | 28 cm³/10min @275°C/5kg | 28 cm³/10min @280°C/5kg |
| Recommended Screw | 2.5–3.0 CR | 2.5–3.0 CR |
Key takeaway: PA6 GF30 processes at 20–25°C lower melt temperature, which saves cycle time (less heating) and reduces energy cost. The mold temperature window is identical for both. PA6 GF30's premium "BFE01" grade is specifically designed for Class-A surface at 85–100°C — no variotherm required, unlike standard PA66 grades which often need higher mold temps or cosmetic additives for a paintable finish.
6. Cost-Performance Analysis
As of mid-2026, Juhai's EXW Ningbo pricing (spot, standard color, 1 MT minimum):
- PA6 GF30 (BFE01): USD 1.95 – 2.25 / kg
- PA66 GF30 (BFE04): USD 2.45 – 2.85 / kg
PA66 GF30 commands a 22–28% premium. For a 10,000-part run of 20 g brackets, that's a material cost difference of USD 1,000 – 1,200 between the two grades.
Cost-performance sweet spot: PA6 GF30 delivers ~85% of PA66 GF30's mechanical performance and ~80% of its thermal performance at 72–78% of the price. The only scenario where PA66 GF30's premium is justified is when you need the 250°C HDT for continuous thermal loading above 150°C — a narrow but critical niche in automotive under-hood and power electronics.
7. Application Recommendations
Use PA6 GF30 (BFE01) when:
- Tensile requirement is under 170 MPa (covers most non-safety brackets)
- Continuous operating temperature stays below 140°C
- You need Class-A cosmetic surface without high mold temperature
- Cost sensitivity matters (consumer electronics, appliance housings)
- Part has tight clearance/tolerance features where lower shrinkage difference helps
- You're replacing a premium PA6 GF grade like DuPont Zytel 73G30L
Use PA66 GF30 (BFE04) when:
- Tensile requirement exceeds 180 MPa (structural load-bearing brackets)
- Continuous temperature exceeds 150°C (under-hood, power electronics)
- You need long-term creep resistance under high pre-load (bolted connections)
- Part needs IATF 16949 automotive certification (BFE04 is certified, BFE01 is ISO 9001)
- Moisture absorption must be minimized for tight-tolerance assemblies
- CTI electrical tracking index ≥ 600 V is required for safety-critical components
8. Frequently Asked Questions
Q: Is PA66 GF30 always stronger than PA6 GF30?
A: PA66 GF30 IS measurably stronger — tensile 190 MPa vs 162 MPa (+17%), flexural 280 MPa vs 245 MPa (+14%). However, the impact difference is much smaller at only ~6% (18 vs 17 kJ/m²). For most general engineering brackets and housings, PA6 GF30 provides sufficient structural performance at a lower cost.
Q: Why is PA66 GF30 HDT so much higher than PA6 GF30?
A: PA66 has a higher melting point (260°C vs 222°C) and denser hydrogen bonding between polymer chains, raising its glass transition temperature. At 1.82 MPa, PA66 GF30 reaches HDT of 250°C while PA6 GF30 is at 198°C — a 52°C difference critical for automotive and high-temperature electrical applications.
Q: Can I substitute PA6 GF30 for PA66 GF30 in my existing mold?
A: In most cases, yes — but check shrinkage carefully. PA6 GF30 has slightly higher flow-direction shrinkage (0.33% vs 0.30%) and cross-direction shrinkage (0.90% vs 0.85%). For tight-tolerance features, expect parts to be ~0.02–0.05 mm larger per 100 mm. Always run a molding trial and CMM check before mass production.
Q: Which absorbs more water?
A: PA6 GF30 absorbs more moisture: 0.95% vs 0.60% after 24-hour immersion (ISO 62). For both grades, pre-drying is mandatory — PA6: 80°C × 4h to <0.08%; PA66: 90°C × 4h to <0.06%. The moisture difference does NOT translate to a meaningful dimensional or processing difference for most parts.
Q: What is the typical price difference?
A: Mid-2026: PA6 GF30 ~ USD 1.95–2.25/kg vs PA66 GF30 ~ USD 2.45–2.85/kg — PA66 GF30 commands a ~22–28% premium. For applications where temperature stays under 180°C, PA6 GF30 delivers 90% of PA66 GF30's HDT at a significantly lower material cost.
Q: Should I use PA6 GF30 or PA66 GF30 for an automotive under-hood bracket?
A: If peak temperature exceeds 180°C or the bracket is structural with bolted pre-load and fatigue cycles, choose PA66 GF30. For clips, guides, light-load housings or brackets where peak temperature is transitory (warm-up spikes under 180°C), PA6 GF30 is cost-effective. Our BFE01 PA6 GF30 has passed 10,000-hour heat-aging at 140°C for non-critical under-hood applications.
Summary: PA6 GF30 and PA66 GF30 are not competitors — they occupy different price-performance tiers. PA6 GF30 wins on processability, surface finish and cost. PA66 GF30 wins on mechanical strength and heat resistance. Choose PA6 GF30 when the application allows; choose PA66 GF30 when temperature or structural requirements demand it. For a personalized grade recommendation for your specific part geometry and operating conditions, contact our R&D team.