PAI · additive grade
PAI-LF
Properties of the LF condition, compared with the other PAI grades.
PAI compounded with graphite plus PTFE lubricant for the lowest dry-running friction coefficient and low wear at high PV, at the cost of strength and ductility versus unfilled resin.
What is PAI-LF?
PAI-LF is PAI in the LF grade — pAI compounded with graphite plus PTFE lubricant for the lowest dry-running friction coefficient and low wear at high PV, at the cost of strength and ductility versus unfilled resin. PAI-LF has a tensile strength of 110 MPa (16 ksi), stronger than 91% of polymer grades. Elongation at break is 5% and the elastic modulus is 7 GPa (1.02 Msi). PAI-LF has a density of 1.51 g/cm³ (0.0546 lb/in³), heavier than 88% of polymer grades. Its glass-transition temperature is 275°C (527 °F). Unfilled (Electrical) is the default condition FabDigit quotes; LF is available on request or by drawing note.
Advantages
- Conducts heat well — 0.55 W/m·K (0.318 BTU/hr·ft·°F), better than 99% of polymer grades
- High service temperature — 250°C (482 °F), better than 94% of polymer grades
- Low, predictable mold shrinkage — 0.3%, better than 91% of polymer grades
- Stiff — 7 GPa (1.02 Msi), better than 89% of polymer grades
- Good UV / weathering resistance — 60/100, better than 80% of polymer grades
Limitations
- High embodied carbon — 14 kg CO₂/kg, worse than 95% of polymer grades
- Limited formability — 8/100, worse than 91% of polymer grades
- Difficult to weld — 5/100, worse than 90% of polymer grades
- Heavy — 1.51 g/cm³ (0.0546 lb/in³), worse than 88% of polymer grades
PAI-LF properties
Typical room-temperature values for PAI-LF — 37 properties are specific to this condition; the rest are grade-level values shared by every PAI grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical4
PAI-LF has a density of 1.51 g/cm³ (0.0546 lb/in³), heavier than 88% of polymer grades. Its glass-transition temperature is 275°C (527 °F).
Mechanical13
PAI-LF has a tensile strength of 110 MPa (16 ksi), stronger than 91% of polymer grades. Elongation at break is 5% and the elastic modulus is 7 GPa (1.02 Msi).
Thermal10
PAI-LF is rated for continuous service to 250°C (482 °F). It conducts heat at 0.55 W/m·K (0.318 BTU/hr·ft·°F), better than 99% of polymer grades. Thermal expansion is 25 µm/m·K (13.9 µin/in·°F).
Electrical7
PAI-LF is an electrical insulator with a dielectric strength of 23 kV/mm (584.2 V/mil) and a resistivity of 1×10¹⁵ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (80/100), worse than 55% of polymer grades. UV resistance is good.
Sustainability3
Producing a kilogram of PAI-LF takes about 250 MJ of energy and emits 14 kg of CO₂ — more than 93% of polymer grades. Typical recycled content is 0%.
Manufacturability7
PAI-LF's machinability is good (58/100, worse than 55% of polymer grades); weldability not recommended (5/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other PAI grades and fills
PAI is also supplied in 4 other conditions. The full side-by-side table is on the PAI overview.
- Unfilled (Electrical)DefaultChoose for insulators, connectors and thin-wall parts needing maximum toughness/elongation and the best dielectric properties.152 MPa tensile
- GF30Choose for stiff, dimensionally stable structural parts that must stay electrically insulating at high temperature.205 MPa tensile
- CF30Choose for the highest stiffness/strength-to-weight and lowest thermal expansion — aerospace brackets, high-speed rotating parts, ESD-tolerant applications.205 MPa tensile
- Bearing GradeChoose for unlubricated or marginally lubricated wear parts — seal rings, thrust washers, bushings, valve seats — where low friction and high PV matter more than elongation.117 MPa tensile
- LFPAI compounded with graphite plus PTFE lubricant for the lowest dry-running friction coefficient and low wear at high PV, at the cost of strength and ductility versus unfilled resin.110 MPa tensile
Working with PAI-LF
Is PAI easy to machine?
Machines like a hard, abrasive engineering plastic — use sharp carbide or PCD tooling, moderate speeds, light finishing cuts, and machine after post-cure to avoid dimensional drift.
Can PAI be welded?
Not fusion weldable in practice; join by epoxy adhesive bonding, PAI adhesive film, or mechanical fasteners with generous bearing area.
Can PAI be formed, bent or molded?
Injection mold with dried resin at 335–365 °C melt and 200–230 °C mold, then post-cure parts in stages to ~260 °C for several days to develop full strength and chemical resistance.
What surface finishes work on PAI?
Natural amber-to-black surfaces polish well and accept plasma or chemical etch before plating/bonding; paint and metallization require thorough drying because of moisture pickup.
PAI chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| titanium dioxidepigment/processing aid in unfilled 4203-type grades | ≈ 3 | 3 |
| PTFEinternal lubricant; ~3% in bearing grades | 0.5 – 3 | 0.5 |
| graphitebearing/wear grades only (4301 ≈ 12%, 4275 ≈ 20%) | 0 – 20 | 12 |
| glass fiberGF30 (5030) variant only | ≈ 30 | 30 |
| carbon fiberCF30 (7130) variant only | ≈ 30 | 30 |
| polyamide-imide (trimellitic anhydride +amide-imide backbone; base resin of all grades | balance | — |
PAI-LF — frequently asked
What is PAI-LF used for?
PAI-LF is typically used for thrust washers, bearings and bearing cages, seal rings for aero-engine and hydraulic systems, insulating washers and spacers, high-temperature electrical connectors and precision gears. In short: highest strength carbon-plastic.
What is the tensile strength of PAI-LF?
PAI-LF has a typical tensile strength of 110 MPa (16 ksi) — stronger than 91% of polymer grades. Strength varies by condition: see the 5 listed tempers.
Is PAI-LF easy to machine?
Reasonably — machinability is rated good (58/100, worse than 55% of polymer grades). Machines like a hard, abrasive engineering plastic — use sharp carbide or PCD tooling, moderate speeds, light finishing cuts, and machine after post-cure to avoid dimensional drift.
Can PAI-LF be welded?
Not readily — weldability is rated not recommended (5/100). Not fusion weldable in practice; join by epoxy adhesive bonding, PAI adhesive film, or mechanical fasteners with generous bearing area.
What surface finishes work on PAI-LF?
Natural amber-to-black surfaces polish well and accept plasma or chemical etch before plating/bonding; paint and metallization require thorough drying because of moisture pickup.
Can PAI-LF be formed, bent or molded?
Injection mold with dried resin at 335–365 °C melt and 200–230 °C mold, then post-cure parts in stages to ~260 °C for several days to develop full strength and chemical resistance.
What is the maximum service temperature of PAI-LF?
PAI-LF is rated for continuous use to about 250°C (482 °F), and briefly to 280°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in PAI-LF?
Yes — PAI-LF is available for CNC machining, sheet metal and injection molding with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Torlon PAI Design Guide and grade datasheets (4203L, 4301, 4275, 5030, 7130) — Solvay Specialty Polymers (2021)
- Duratron T4203 / T4301 / T4501 PAI stock shape datasheets — Mitsubishi Chemical Advanced Materials (Quadrant) (2022)
- TECATOR / PAI machinable stock shapes datasheet — Ensinger (2022)
- CAMPUS / UL Prospector polyamide-imide typical property records — CAMPUS Plastics (2023)
- ASM Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.