Wire drawing dies are tools with highly-polished, specially-shaped holes through which wire is drawn to reduce its diameter. They have a metal case and a nib made of tungsten carbide (TC), polycrystalline diamond (PCD), or natural diamond.
When selecting wire drawing dies, wire material and drawing parameters are important specifications to consider. Typically, wire materials include copper, stainless steel, aluminum alloy steel, tungsten, galvanized high-carbon steel, gold, silver, stainless steel, low-carbon steel, molybdenum, and nickel. Drawing parameters include measurements such as inlet diameter, bell radius, entrance angle, approach angle, bearing and back relief. Elongation, the ratio of length after drawing to the length prior to drawing, is also an important consideration when choosing wire drawing dies.
There are many different types of wire drawing dies. Examples include standard wire drawing dies, PCD wire drawing dies, TC wire drawing dies, and enameling wire drawing dies. Standard wire drawing dies have a well-defined reduction angle that reduces drawing force and provides uniform die-formation with a consistent surface finish. PCD wire drawing dies use polycrystalline diamond (PCD), a synthetic material which provides superior resistance to cracking and wear. TC wire drawing dies are made from tungsten carbide, an extremely hard and scratch-resistant material that is often used in tool bits. Tungsten carbide wire drawing dies are often used to draw thicker wires, and in applications where PCD dies are too expensive. Enameling wire drawing dies are used with enameled wires and may feature internal geometries which are suitable for very small wire sizes.
Wire drawing dies are used with a variety of wire drawing tools and equipment. Pull-in dogs are used to grip a wire’s end as it enters the die. After the pull-in dog is fastened to the block, the wire is drawn through the die. Wire drawing dies are also used with both single-block and multiple-block machines. With single-block equipment, the wire passes through a die and collects on a standard block. With multiple-block machines, the wire is pulled through a die and wrapped around a slightly-tapered block. The wire then moves upward onto collector pins and exits the upper section to reduce back tension. Typically, inverted drawing machines or gravity blocks are used with coarser wire sizes, or to draw wire that requires superior surface quality. Wire drawing dies for these machines are available from a variety of suppliers.