Dumet
DUMET: WIRE / RIBBON
Dumet is a glass-to-metal sealing alloy. It is a bimetal made of a nickel-iron core encased in an oxygen-free-high- conductivity (OFHC) copper sheath. Dumet wire is used as a glass-to-metal seal in manufacturing of lamps, diodes, and capacitor slug leads. It is used as the pinch-lead in Lead-in-Wires that are used in incandescent, fluorescent tube, automotive, halogens, HID, decorative, and other special purpose lamps. JLC boasts of being the world’s largest producer of lamp grade Dumet wire.
Grades of Supply:
- Bare Dumet Wire
- Oxidized Dumet Wire
- Borated Dumet Wire
- Nickel-Plated Dumet Wire
All grades are supplied as annealed wire.
Nominal Chemical Composition (%)
| Alloy | Ni | C | Mn | Si | S | P | Fe |
|---|---|---|---|---|---|---|---|
| NiFe42 Core | 41-43 | Max 0.05 | Max 1.0 | Max 0.30 | Max 0.02 | Max 0.02 | Balance |
Two grades are available which are identified with Copper sheath as follows:
| Copper* Sheath | |
|---|---|
| 24 ± 2 % of the total weight | 26 ± 2 % of the total weight |
* Min 99.99% OFHC Copper
Nominal Physical & Electrical Properties
(for cold drawn & annealed wire)
| Density | Electrical Resistivity at 20°C | |
|---|---|---|
| Alloy | g/cm³ | µΩ-cm |
| Dumet wire | 8.35 | 6-9 |
Nominal Mechanical Properties
(for cold drawn & annealed wire)
Alloy Dumet wire | Coeff. of Linear Expansion between 20-400°C 10-6/°C Radial: 8.5-10 Axial: 5.5-7.0 | Tensile strength N/mm² Min: 400 Max: 600 | Elongation % at L0=100 mm Nominal dia in mm Min: 20 Max: 30 |
For Borated and Oxidized Dumet, color of the wire surface is as per ASTM color standard F29-63T.