NiFe 70/30 & NiFe 52/48 - Nickel Iron wire have been developed to produce high-temperature coefficients of resistance (Positive Temperature Coefficient or PTC) in order to provide a ‘self-limiting’ heating wire.
When the temperature of the wire is around 250 °C the element resistance will have doubled and the power output will have halved.
Improved temperature control
Reduced energy consumption
Reduced power if overheating
High start-up power.
Nickel Iron wire are available in sizes down to 0.09 mm.
Physical and Mechanical Properties of Nickel Iron Wire
| | Units | NiFe 70/30 | NiFe 52/48 | |
|---|---|---|---|---|
| Maximum continuous operating temperature in air | °C | 600 | 600 | |
| °F | 1100 | 1100 | ||
| Nominal composition | % | Ni 70 | Ni 52 | |
| Fe 30 | Fe 48 | |||
| Density at 20°C | g/cm³ | 8.45 | 8.2 | |
| lb/in³ | 0.305 | 0.296 | ||
| Resistivity at 20°C | µΩcm | 21 | 37 | |
| Ω/cmf | 130 | 220 | ||
| Coefficient of thermal expansion, | 20 – 100°C | 1/K | 15 x 10^6 | 10 x 10^6 |
| 68 – 212°F | 1/°F | 8.3 x 10^6 | 5.6 x 10^6 | |
| Thermal conductivity at | 20°C | W/mK | 17 | 17 |
| 68°F | Btu.in/ft².h.°F | 120 | 120 | |
| Specific heat capacity at | 20°C | kJ/kgK | 0.52 | 0.5 |
| 68°F | Btu/lb°F | 0.12 | 0.12 | |
| Melting point (approx.) | °C | 1430 | 1435 | |
| °F | 2610 | 2620 | ||
| Magnetic properties (up to Curie point) | Magnetic | Magnetic | ||
| Curie point | °C | 610 | 530 | |
| °F | 1130 | 990 | ||
| Tensile strength Rm(0.5 mm wire) | N/mm² | 640 | 610 | |
| lb/in² | 93000 | 88000 | ||
| Yield point Rp0.2(0.5 mm wire) | N/mm² | 340 | 340 | |
| lb/in² | 49000 | 49000 | ||
| Elongation at break (approx.) (0.5 mm wire) | % | 30 | 30 | |
Temperature Dependant Factors
Reference temperature 20°C
| Temp °C | 100 | 150 | 200 | 250 | 300 | 350 | 400 | 450 | 500 |
| Temp °F | 212 | 302 | 392 | 482 | 572 | 662 | 752 | 842 | 932 |
| 70/30 Ni/Fe | 1.35 | 1.57 | 1.8 | 2.05 | 2.3 | 2.56 | 2.82 | 3.1 | 3.4 |
| 52/48 Ni/Fe | 1.33 | 1.53 | 1.73 | 1.93 | 2.13 | 2.32 | 2.49 | 2.64 | 2.77 |
The figures given in these tables represent nominal or typical values.
Information contained within this technical data sheet is based upon the general experience of Scott Precision Wire Ltd and is believed to be correct at the time of issue.
No warranty is given or is to be implied from the details above.
Customers are advised to carry out independent tests in order to determine the suitability of any Scott Precision Wire Ltd product for an application.