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.
Grade selection depends on the lamp type and the manufacturing process of the lamp maker.
| 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
| Alloy | Density | Electrical Resistivity at 20°C |
|---|---|---|
| g/cm³ | µΩ-cm | |
| Dumet wire | 8.35 | 6-9 |
| Alloy | Coeff. of Linear Expansion between 20-400°C 10-6/°C |
Tensile strength N/mm² |
Elongation % at L0=100 mm Nominal dia in mm |
|||
|---|---|---|---|---|---|---|
| Radial | Axial | Min | Max | Min | Max | |
| Dumet wire | 8.5-10.0 | 5.5-7.0 | 400 | 600 | 20 | 30 |
Surface Finish
For Borated and Oxidized Dumet, color of the wire surface is as per ASTM color standard F29-63T.
The color has been divided into three parts:
| Light | Medium | Dark |
|---|---|---|
| 7.5R - 0.5YR | 3.5R - 7.5R | 2.5R - 3.5R |
For Nickel plated Dumet wire, standard plating thickness is min 2 microns.
Packaging
Available in different types of spools or drums/barrels based on customer specification. Common spool used has the following dimensions:
| Spool Type | Traverse | Bore | Flange | Tare weight |
|---|---|---|---|---|
| mm | mm | mm | gm | |
| Dumet-SP | 52 | 48 | 100 | 60 |
Barrel/drum packaging and other standard DIN spools are also available upon request. Dumet spools are individually sealed with plastic film and put in an air-tight plastic container with an activated dessicant material.
It is advisable to use the wire within six months from the date of manufacturing for best performance. The shelf life of borated, oxidised and bare dumet is only six months from the date of manufacturing.
Click here to download this data sheet in PDF format.