Useful tips for working with nichrome

Calculation of electric heating elements made of nichrome wire

Allowable current
(I), A 1 2 3 4 5 6 7 Diameter (d) nichrome
at 700 ° C, mm 0.17 0.3 0.45 0.55 0.65 0.75 0.85 Wire section
(S), mm2 0.0227 0.0707 0.159 0.238 0.332 0.442 0.57 Length of nichrome wire for the production of electric heaters is determined based on the required power. Example: Determine the length of the nichrome wire for a tile heating element with power P = 600 W at Umains= 220 V. Solution:
1) I = P / U = 600/220 = 2.72 A
2) R = U / I = 220 / 2.72 = 81 Ohms
3) According to these data (see the table), we choose d = 0.45; S = 0.159, then the length of nichrome l = SR / ρ = 0.15981 / 1.1 = 11.6 m,
where l — wire length (m); S — conductor cross-section (mm2); R — wire resistance (Ohm); ρ — resistance (for nichrome ρ = 1.0 ÷ 1.2 Ohm mm2/ m). Nichrome Spiral Repair By winding the ends of a burnt nichrome spiral onto a piece of copper wire and bending both ends of that wire with pliers, you will give the spiral a second life. The copper wire must be at least 1 mm in diameter.

Nichrome soldering

Brazing of nichrome (nichrome with nichrome, nichrome with copper and its alloys, nichrome with steel) can be done with solder POS 61, POS 50, using a flux of the following composition, g: technical vaseline — 100, zinc chloride powder — 7, glycerin — 5. The components are thoroughly mixed until a homogeneous mass is obtained.

The surfaces to be joined are thoroughly cleaned with an emery cloth and wiped with a swab dipped in a 10% alcoholic solution of copper chloride, treated with flux, preserved and only then soldered. When tinning nichrome wire, there is the problem of making a reliable electrical connection of nichrome wire to copper wire—after all, nichrome does not lend itself well to tinning with ordinary rosin flux. It is much easier to irradiate the end of the nichrome wire if ordinary powdered citric acid is used as the flux. A very small amount of citric acid powder (in the volume of two match heads) is poured onto a wooden stand, the bare end of the wire is placed on top of the powder, and with a little effort the tip of a hot soldering iron is driven into it. The powder melts and wets the wire well.
The tinned wire is placed on rosin and tinned again — this is necessary to remove the remaining citric acid from the wire. Using the described method, you can tin-plate small items of steel and other metals.