Black Tungsten Wires and Clean Tungsten Wires, Tungsten Filament Wires

We supply tungsten wire, tungsten bar, tungsten plate, tungsten sheet, tungsten rod, tungsten electrode, tungsten fabricated parts, tungsten alloy, tungsten copper alloy, tungsten heavy alloy. Please contact with our sales department for more details.

We produces two types of tungsten wire - Pure and WAL (K-Al-Si doped).

Pure tungsten wire is produced in sizes above. 020 inches in diameter. Typical usage is for restraightening into rod products and for applications where there is a low alkali content requirement.

WAL is wire which has been doped with trace amounts of potassium, causing the wire to exhibit an elongated interlocking grain structure with non-sag properties after recrystallization. WAL wire is produced in sizes from less than 0.02mm up to 6.5mm in diameter and is used largely for lamp filament and wire filament applications.

Dimensions and Tolerances
Wire diameters are generally expressed in terms of mm(or inches). For thin wires from 0.02mm up to 0.5mm in diameter, the diameter of the wire is measured by weight per unit length. That is, the weight expressed in mg of a 200 mm length of wire.

The standard diameter tolerance is 3% of the weight measurement. Closer tolerances are available, depending upon the application for the wire product.

For thicker wires from 0.5mm up to 6.5mm in diameter, the mm measurements are used. The tolerances are expressed as a percentage of the diameter. Standard tolerance is 1.5%.

Tensile Strength
Tensile strength for tungsten wire is usually expressed in grams per milligram weight of a 200mm (or) g/mg/200mm. The normal range of values is from 40 to 110 grams. In general, as tensile strength increases, wire straightness decreases.

Straightness
Wire may be finished in the unstraightened or as drawn condition and is controlled to FOTMA's internal standards, In addition, wire can be straightened via mechanical or heat treating processes. Typically, the measure of the straightness of a tungsten wire is obtained by cutting a ten inch long piece of wire and allowing it to lie on a flat clean surface. The maximum deviation from a straight line along its length is the quantitative measure of its straightness. In general, as the degree of straightness increases, tensile strength decreases.

Splits
Longitudinal cracks with a depth of more than 15% of the wire diameter are called splits. The wire is checked for splits with an eddy current split detector. The split level for a given length of wire is typically less than 5%.

Quality and Finish
Wire is free of scratches, kinks and distortions insofar as they are harmful to the intended end use of the product. Surface finish is supplied in the black, as drawn condition, where drawing lubricants and oxides are retained on the surface, or in the cleaned condition by firing in hydrogen or electrochemical etching.

Spooling
Wire is spooled on clean, defect free spools. For very large diameters, tungsten wire is self coiled. Spools are level filled without piling near flanges. The outer end of the wire is properly marked and attached securely to the spool or self coil.