A cylindrical bushing used to create the die nib.

The nib, a cylindrical bushing with an inside contour design for wiredrawing, is made of a hard material, such as tungsten carbide or diamond that is too expensive or too brittle to become the whole die. The carbide nibs are cold pressed with the inside contour formed before the final sinter step that gives the material its hardness. Large diameter nibs are machine turned or drilled into the die contour before the final sintering is done. The nib is ground on the outside diameter before cold pressing or heat shrinking the nib into a metal casing that increases the nib strength and for mounting in the wiredrawing machine. This is the working part of a wiredrawing die. The nib plus casing is the die. See Die.

A wiredrawing die made from one of the forms of diamond. They are more expensive than carbide dies but wear longer and are often used for drawing finer wire sizes. Industrial diamonds often draw to 0.005 to 1 mm (0.002 to 0.04 in.) for harder wires and up to 2.5 mm (0.1 in. for copper. They are specified in B.S. 2946, which deals with quality of the dia­mond, the mounting, casing, size tolerance and marking. See entries for Die, Diamond Natural; Die, Synthetic Single Crystal; and Die, PCD Diamond.

The industrial grade of natural diamond is primarily used for small diameter nonferrous wiredrawing and for achieving better surface finishes on the drawn wire.

Machines designed to manufacture the die from the rough cored or drilled condition and/or the reworking of worn dies.

A man-made polycrystalline diamond (PCD) is often used for drawing nonferrous metals. They can also be used for stainless steel and specialty alloy products in smaller diameters where the higher cost can be justified over carbide because of longer die life or improved wire tolerances. PCD material has replaced natural diamonds in many applications.

See Dies, Cored Nib.

Dies having non-circular cross sections, for instance, square, hex­agon, etc.

A die that has two pairs of rollers, a ver­tical pair with an oval groove to form an oval shape, followed by rolling to a round shape with a horizontal pair. Ideally, they offer lower power consumption, higher drawing speed, reduction in inter­mediate annealing and cleaning, improved wire properties and elimination of expen­sive lubricants. However, they take longer to set up, cannot be used for finishing passes and the shape of the oval groove is critical to ensure that the wire does not turn over and that it will be round after the next rolling.

These were used before diamond dies and may still be useful for soft metals such as gold and silver. Their cost is less than that of diamond dies, but performance may be the same as that of sintered carbide dies. Sapphires were also used.

See Die, Ruby.

A pair of steel blocks, which, when put together in a die holder, form a circular or sector shaped hole. Or, a solid die (carbide, natural, or polycrystalline) used to collect and hold multiple wires in a single group or “strand.”

The single-crystal man-made diamond die can be used in applications where natural diamonds are used. The crystal has a stable strength that corresponds to the highest value for natural diamond. It is often used in dies that must bear great stress.

The most commonly used die material, it is most often used for ferrous drawing applications. Normal wire die sizes using carbide is .020 to 19.05 mm (.008 to .750 in.). Carbide is softer than diamond but is a tougher and less expensive material that can be reworked into larger sizes more than its diamond counterpart. It often is replaced by diamonds, however, when either increased die life and/or closer diameter tolerance is required.

Any electrical insulating material that is a non-conductor of electricity.

That property of an imperfect dielectric whereby there is an accumulation of electric charges within the body of the material when it is placed in an electric field.

The voltage required to cause an electrical failure or breakthrough of the insulation. It is divisible by thickness to give dielectric strength.

Coatings that offer high temperature resistance with thinner walls and durability and are applied by extrusion to electrical conductors.

(K). It is a measure of the dielectric loss through an insulation and also indicates the charging current required for a conductor. It determines the electrostatic energy stored per unit volume for unit potential gradient. This numerical value usually is given relative to a vacuum. Also called permittivity and specific inductive capacity.

The change in relative capacitance due to change in frequency.