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38 clicksTwo issues need to be distinguished:
① Insufficient hardness → Improve rigidity and surface hardness.
② Brittle fracture → Improve toughness and notched impact resistance, reduce stress cracking.
They are often contradictory: adding glass fiber increases hardness and rigidity, yet makes the material more brittle with poorer notched toughness.
PA66 + 15~30% GF
Advantages: Greatly improved tensile strength, flexural modulus and Rockwell hardness; better heat resistance.
Risk: Higher glass fiber loading leads to brittleness and lower notched impact; thin-walled parts or sharp corners are prone to cracking.
Supporting improvement for brittleness: Add toughener (MAH-grafted POE/EPDM) to make toughened glass-fiber-reinforced PA66.
Typical grade: PA66+25%GF + toughener, balancing hardness and impact resistance, widely used for automotive structural parts.
Option 2: Toughening Modification (Mainly solve brittle cracking; note: pure toughening reduces hardness)
PA66 + 8~15% grafted elastomer (POE-g-MAH / EPDM-g-MAH).
Advantages: Markedly higher notched impact strength, less brittle fracture at low temperature, improved resistance to stress cracking.
Disadvantages: Modulus, hardness and heat resistance decrease.
Suitable for parts with acceptable baseline hardness but prone to cracking or low-temperature brittle failure.
Option 3: Combined Glass Fiber + Toughening Modification (Most common, balancing hardness and crack resistance)
Recommended formulation concept:
PA66 + 20~30% glass fiber + 6~12% grafted toughener + minor lubricant / antioxidant.
Glass fiber provides hardness and rigidity; toughener improves matrix toughness and suppresses brittle cracking.
Suitable for most structural and transmission components; the mainstream modification solution apart from the wear-resistant grades you checked earlier.
Option 4: Mineral Filling (Low warpage, higher hardness, slightly better toughness than GF grades)
PA66 + Talc / Mica
Higher hardness, low cost, low warpage.
Strength improvement inferior to glass fiber grades; mediocre toughness, not recommended for heavy-load applications.
PA66/PP alloy, PA66/ABS alloy
Excellent stress-cracking resistance and toughness.
Rigidity, hardness and heat deflection temperature are lower than GF-reinforced PA66.
Supplementary Notes: Apart from formulation, cracking often arises from processing & part design.
Part design: Avoid sharp corners and abrupt wall-thickness changes; use radius transitions. Sharp corners are high-risk zones for brittle cracking.
Molding: Thorough drying (PA66 becomes brittle easily with moisture!), proper packing pressure, sufficient mold temperature to minimize residual stress.
Post-treatment: Conditioning (hot water immersion / humid aging). Water absorption raises PA66 toughness, yet slightly reduces dimension stability and hardness.
Quick Selection Guide
High hardness priority, brittleness acceptable: Standard glass-fiber-reinforced PA66.
Main pain point: brittle cracking, sufficient existing hardness: Toughened PA66.
Require both adequate hardness and crack resistance: Toughened GF-reinforced PA66 (First choice).
* The application cases shown may not fully match your target products. Please inform us of your specific requirements, and we will assist you in material selection.
