Overview of several common materials for wire drawing dies

After decades of development, many new drawing die materials have emerged. According to the type of material, the wire drawing die can be divided into alloy steel die, cemented carbide die, natural diamond die, polycrystalline diamond die, CVD diamond die and ceramic die. In recent years, the development of new materials has greatly enriched the application range of wire drawing dies and improved the service life of wire drawing dies.

(1) The alloy steel mold is an early material for the drawing die. The materials used to make the alloy steel mold are mainly carbon tool steel and alloy tool steel. However, due to the poor hardness and wear resistance of the alloy steel mold and short life, it cannot meet the needs of modern production, so the alloy steel mold is quickly eliminated, and the alloy steel mold is almost invisible in the current production and processing.

(2) The cemented carbide mold is made of cemented carbide. Cemented carbide is a tungsten-cobalt alloy whose main components are tungsten carbide and cobalt. Tungsten carbide is the "skeleton" of the alloy, which is mainly used for hard wear resistance; cobalt is a bond metal and is a source of alloy toughness. Therefore, the cemented carbide mold has the following characteristics compared with the alloy steel mold: high wear resistance, good polishing property, small adhesion, low friction coefficient, low energy consumption, high corrosion resistance, and these characteristics make the brushed carbide The mold has a wide range of processing adaptability and has become the most widely used drawing die.

(3) Natural diamond is an allotrope of carbon. The mold made with it has the characteristics of high hardness and good wear resistance. However, natural diamond is more brittle and difficult to process, and is generally used to manufacture wire drawing dies having a diameter of 1.2 mm or less. In addition, natural diamonds are expensive and supply is scarce, so natural diamond molds are not the economical and practical drawing tools that people ultimately seek.

(4) Polycrystalline diamond is formed by a carefully selected high quality synthetic diamond single crystal and a small amount of a bonding agent such as silicon or titanium, which is polymerized under high temperature and high pressure conditions. Polycrystalline diamond has high hardness and good wear resistance. Compared with other materials, it has its own unique advantages: due to the anisotropy of natural diamond, during the drawing process, when the entire hole is around When working, natural diamond will have preferential wear at a certain position of the hole; and polycrystalline diamond is polycrystalline and isotropic, thus avoiding the phenomenon of uneven wear of the die hole and the non-circular hole. Compared with cemented carbide, the tensile strength of polycrystalline diamond is only 70% of the commonly used cemented carbide, but 250% harder than the hard alloy, so that the polycrystalline diamond mold has more advantages than the cemented carbide mold. . The wire drawing die made of polycrystalline diamond has good wear resistance, uniform inner hole wear, strong impact resistance, high wire drawing efficiency, and the price is much cheaper than natural diamond. Therefore, polycrystalline diamond wire drawing dies are widely used in the wire drawing industry.

5) CVD (Chemical Vapor Deposition) It has the advantages of single crystal diamond smoothness, temperature resistance, wear resistance of polycrystalline diamond and low price, and it is very good in replacing the rare natural diamond to prepare the drawing die tool. Good results, its widespread use will bring new vitality to the wire drawing industry.

(6) High-performance ceramic materials have the characteristics of high hardness, good wear resistance, strong chemical stability, excellent high-temperature mechanical properties and difficult adhesion to metals, and can be widely used in the processing of difficult-to-machine materials. In the past three decades, the addition of various carbides, nitrides, borides, oxides, whiskers or small amounts of metals has been developed due to the effective control of raw material purity and grain size in the ceramic material manufacturing process. And the use of a variety of toughening and strengthening mechanisms, so that the strength, toughness and impact resistance of ceramic materials have been greatly improved.

    (7) The coated wire drawing die is a newly developed new technology. The main method is to coat the metal film on the brushed die of the cemented carbide. The metal film is a pure titanium coating, which has the advantages of good finish and temperature resistance, titanium wear resistance and low cost, and has achieved good results in replacing the hard wire drawing die tool.