Wire Drawing Dies

In order to ensure high-quality wire and effectively control the cost of wire drawing dies, attention should be paid to the following aspects:

1. Ensure smooth operation of wire drawing equipment. The wire drawing drums and wire guide wheels should be smooth and flexible, and their run-out tolerances should be strictly controlled. If it is found that the drum and guide wheel have worn grooves, they should be repaired in time. Good lubrication conditions are important conditions to ensure the surface quality of the wire and extend the life of the mold.

Always check the lubricating strength index to remove the copper powder and impurities in the lubricating oil so that it will not contaminate the equipment and die holes. If the lubrication fails, the lubrication system must be replaced and cleaned in time.

2. Reasonable collocation of molds is the key element to ensure the surface quality of the wire rod, control the dimensions accurately and consistently, reduce the wear of the wire drum and reduce the operating load of the equipment. For the sliding wire drawing machine, it is necessary to be familiar with the mechanical elongation of the equipment and choose the sliding coefficient reasonably, which is the first step of mold matching.

The hole type of the mold is selected according to the material of the wire to be drawn and the area reduction rate of each wire drawing. Generally speaking, the harder the wire is drawn, the smaller the compression angle of the mold and the longer the sizing area; and vice versa.

The area reduction rate of each wire drawing is also closely related to the compression angle of the corresponding mold. The compression angle should be adjusted appropriately according to the size reduction rate.

3. Effective maintenance and repair of molds is essential to reduce the cost of wire drawing. Due to the vibration of the wire, a slight ring abrasion first occurred in the area contacting the wire in the compression zone of the drawing die, and then continued to expand to the sizing area, resulting in a serious decrease in the surface quality of the wire and an increase in the wire size.

Not only that, severe wear and tear will cause lateral cracks (mainly in the drawing of soft filaments) or longitudinal cracks (mainly in the drawing of hard filaments), so that the drawing die is scrapped prematurely. Therefore, it is necessary to scientifically formulate wire drawing die maintenance specifications according to the type of wire to be drawn and the characteristics of the wire drawing machine.

Under normal circumstances, slight annular wear only needs to be polished to re-use, or a slightly enlarged diameter can also meet the drawing requirements. Excessive wear will greatly reduce the number of mold repairs, and even scrap, making the cost of wire drawing increased.

Why Is the Drawing Die the Basis of Drawing Die Quality?

The drawing die is a mold for manufacturing metal wire, which is processed from coarse to fine, and gradually reaches the required size. This special mold is what we call today. Next, we will learn more about the specific use of the product.

The products produced by the wire drawing die are widely used in the fields of TV radar, instrumentation and aerospace. Therefore, related products and various aluminum alloys are made of ordinary drawing dies, diamond drawing dies, and PCD wire drawing dies.

At the same time, natural diamond as a raw material has strong wear resistance and a long service life.

The pipe production process includes several process steps of lamination, die drawing and turning. The products are divided into different varieties and have a wide range of uses.

With the continuous development of society, the quality and efficiency of this product are also constantly improving.

There is room for development in the process of adaptation. In addition, in terms of material selection and processing technology, the product has more advantages.

Therefore, it has a wide range of uses and brings great help to our lives. The above drawing die is the basis of drawing quality.

What Are the Factors That Affect the Service Life of Wire Drawing Dies?

The service life of TC Dies will not only affect the production cost but also affect the stability of product quality and production efficiency.

What factors will affect the service life of the drawing die?

• The Influence of the Production Materials on the Service Life of the Drawing Die

The mold material is one of the important factors that affect the service life of the mold. The performance of various mold materials in terms of hardness, corrosion resistance, wear resistance, fracture resistance, plastic deformation resistance, cold and hot fatigue resistance, etc. are very different, so the performance of the mold material should meet the specific conditions for the use of wire drawing dies. Otherwise, it will inevitably cause the early failure of the mold.

• The Effect of the Hole Structure on the Service Life of the Drawing Die

With the improvement of modern drawing technology, traditional mold design concepts are changing. New concepts have been introduced into modern mold design. New “straight” drawing dies are increasingly replacing traditional “arc” drawing dies. After a series of improvements, the service life of the linear drawing die is 3-4 times higher than that of the arc drawing die, and it is especially suitable for high-speed drawing.

• The Influence of the Production Process on the Service Life of the Drawing Die

During the manufacturing process of wire drawing dies, multiple processes such as forging, machining and heat treatment are required. If the manufacturing process of any process is unreasonable, it may be that the performance of the mold steel is reduced, structural defects are formed, and the hidden dangers of early mold failure are generated.

• The Influence of Working Conditions on the Service Life of the Drawing Die

The processed materials with different thicknesses and different materials have a great influence on the service life of the drawing die. The greater the strength and thickness of the processed material, the greater the force the mold needs to withstand, and its service life is relatively low. If the processed material and the mold material have a greater affinity, there may be adhesion and wear with the mold during the molding process, resulting in a reduction in the service life of the mold.

• The Influence of Reasonable Use and Maintenance of Wire Drawing Die on Its Life

During the use of the drawing die, it is reasonably used to maintain the drawing die and improve the repair level of the die. It is an important way to extend the service life of the die. In addition, good lubrication can effectively reduce friction and friction heat. Thereby reducing mold wear and improving the service life of wire drawing mold.

1.Usually refers to various molds for drawing metal wires, as well as drawing dies for drawing optical fibers. The center of all drawing dies has a certain shape of hole, round, square, octagonal or other special shapes. When the metal is pulled through the die hole, the size becomes smaller and even the shape changes. Steel molds are sufficient when drawing soft metals (such as gold and silver). The steel molds can have multiple holes with different diameters.

The drawn steel wire (steel wire) generally uses a cemented carbide mold (Tungsten carbide nib). The typical structure of this mold is a cylindrical (or slightly tapered) cemented carbide core tightly embedded in a round steel sleeve. In the (case), the inner hole of the core includes a bell radius, an entrance angel, an approach angle, a bearing, and a back relief. For drawing non-ferrous metal wires, such as copper and aluminum, wire drawing dies similar to wire dies are also used. The shape of the inner hole is slightly different. The fine wire can be used for polycrystalline dies (man-made diamonds), and also for natural diamond.

Some of the soldiers in the ancient Chinese terracotta warriors and horses of Qin Shihuang could see metal wires on the stone armor, so it is estimated that someone had mastered the drawing technique at that time. In the Ming Dynasty book of Tiangong Kaiwu, we can see the needle making process, among which the drawing die is used.

First, the definition of drawing die
Usually refers to various molds for drawing metal wires, as well as drawing dies for drawing optical fibers. The center of all drawing dies has a certain shape of hole, round, square, octagonal or other special shapes. When the metal is pulled through the die hole, the size becomes smaller and even the shape changes.

Second, the type of drawing die
1. Steel molds—Steel molds are sufficient when drawing soft metals (such as gold and silver). There can be multiple holes with different apertures on the steel mold.

2. Cemented carbide mold—Tungsten carbide nib is generally used for drawing steel wire (steel wire). The typical structure of this mold is a cylindrical (or slightly tapered) cemented carbide core. The ground is embedded in a round steel case (Bell radius), entrance angel (Entrance angel), deformation angle (approach angle), sizing belt (bearing) and Exit angle (back relief).

3. Wire molds—For drawing non-ferrous metal wires, such as copper and aluminum, wire drawing dies similar to wire dies are also used. The shape of the inner hole is somewhat different.

4. Polycrystalline mold-Polycrystalline mold (man-made diamonds) can be used for drawing thin wires, as well as wire-drawing molds using natural diamonds.

Third, the use of drawing die

The wire drawing die is a very important consumable die for drawing wires by various metal wire manufacturers (such as wire and cable factories, steel wire factories, welding wire factories, etc.). The scope of application of wire drawing die is very wide. It is mainly used for drawing linear and difficult-to-machine objects such as bars, wires, wires, pipes, etc. It is suitable for drawing processing of metal and alloy materials such as steel, copper, tungsten, molybdenum, etc.

Since the cost of the wire drawing die accounts for more than 1/2 of the wire drawing cost, how to reduce the cost of the wire drawing die and increase its service life is an urgent issue for metal wire production units.

In order to improve the production competitiveness of foreign metal products industry, more and more attention is paid to the improvement of the quality of the drawing die and the manufacturing process. Starting from the improvement of the life of the drawing die, the material, structure, manufacturing process, manufacturing equipment and testing instruments of the drawing die have been studied. Systematic research has developed composite drawing dies, new drawing die materials, new surface coating technologies, and new hole design methods for drawing dies, which have promoted the development of wire drawing production in the world.

China is a major wire producer and its output ranks among the highest in the world. China’s wire drawing die manufacturing industry has developed rapidly since the 1980s. With the continuous improvement of wire drawing die manufacturing level and continuous improvement of production technology, China’s wire drawing die manufacturing technology has further developed, especially in the materials of wire drawing die, Great progress has been made in such areas as structure. But in general, there is still a big gap with foreign countries. Although the types of wire drawing dies produced abroad are similar to those of domestic ones, the materials and processes used are more advanced. The processing accuracy, durability and wear resistance of wire drawing dies are better than those of our products. Therefore, strengthening the management of mold making, improving the quality level of wire drawing dies, and promoting the progress of mold making technology are important issues currently facing the mold making industry.

2. Drawing die material
After decades of development, many new wire drawing die materials have appeared. According to the type of material, the wire drawing die can be divided into alloy steel die, hard alloy 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 increased the service life of wire drawing dies.

(1) Alloy steel mold is an early material for wire drawing die manufacturing. The materials used to make alloy steel molds are mainly carbon tool steel and alloy tool steel. However, due to the poor hardness and abrasion resistance of the alloy steel mold, and the short life, it cannot meet the needs of modern production, so the alloy steel mold was quickly eliminated, and almost no alloy steel mold can be seen in the current production process.

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

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

(4) Polycrystalline diamond is made by carefully selecting high-quality artificial diamond single crystals with a small amount of binders such as silicon and titanium, and polymerizing under high temperature and pressure conditions. Polycrystalline diamond has high hardness and good abrasion 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 surrounded by Under working conditions, natural diamond will wear preferentially at a certain position of the hole;

Polycrystalline diamond is polycrystalline and has the characteristics of isotropy, thereby avoiding uneven wear of mold holes and out-of-round mold holes. Compared with cemented carbide, the tensile strength of polycrystalline diamond is only 70% of common cemented carbide, but 250% harder than cemented carbide. In this way, polycrystalline diamond mold has more advantages than cemented carbide mold. . The wire drawing die made of polycrystalline diamond has good wear resistance, uniform bore wear, strong impact resistance, high wire drawing efficiency, and the price is much cheaper than natural diamond. Therefore, polycrystalline diamond dies are currently widely used in the wire drawing industry.

(5) CVD (chemical vapor deposition) coating wire drawing die is a newly developed new technology. The main method is to coat the diamond film on the carbide wire drawing die. Diamond film is a pure diamond polycrystal. It has the advantages of single crystal diamond’s smoothness and temperature resistance, as well as the abrasion resistance and low price of polycrystalline diamond. It has achieved good results in preparing wire drawing tools instead of rare natural diamond. Effect, its widespread use will bring new vitality to the wire drawing industry.

(6) High-performance ceramic materials have the characteristics of high hardness, good abrasion resistance, strong chemical stability, high-temperature mechanical properties, and difficulty in bonding with metals. They can be widely used in the processing of difficult-to-process materials.

Wire drawing die is a very important consumable product used by various metal wire manufacturers to draw wires. The application range of metal wire drawing dies is very wide, mainly used for drawing straight and difficult-to-machine objects such as bars, wires, pipes, etc., and generally suitable for drawing processing operations of metal and alloy materials such as steel, copper, tungsten, molybdenum, etc. Since the cost of the carbide wire drawing die can reach more than 1/2 of the wire drawing cost, how to reduce the consumption cost of the wire dies and increase its service life has become the primary problem.
We shall discuss this problem today.

1.The wire used for drawing must be pretreated.

(1)Surface pretreatment:
The wire with dirty surface and impurities should be cleaned and dried before drawing;
Wires with a lot of oxide scale on the surface must be acidified and dried before drawing;
For wires with peeling, pits, heavy leather, etc. on the surface, they must be polished by a grinder and then drawn;

(2) Heat treatment: For wires with excessive hardness or uneven hardness, the hardness should be reduced by annealing or tempering first, and the wire can be drawn after maintaining good hardness uniformity.

2.Maintain a proper drawing surface shrinkage rate

Cemented carbide wire drawing dies have the characteristics of being hard and brittle. If they are used for shrinking drawing with large area shrinkage, it is easy to cause the die to bear the stress and easily break and scrap.

Therefore, we should select the appropriate area shrinkage for drawing according to the different mechanical properties of the wire.
Generally, the single-pass surface shrinkage rate should not exceed 20% when using tungsten carbide wire guide dies to drawing the stainless steel wire.

3. Use lubricants with good lubricating properties

During the drawing process, the quality of lubricant or wire drawing powder and the supply of wire-drawing lubricants all affect the service life of the drawing die. Therefore, the lubricant is required to have a stable oil base, good oxidation resistance, excellent lubricity, cooling and cleaning properties, and always maintain the best lubrication state throughout the production process.

During use process, we should observe the condition of the lubricating oil constantly. If severe discoloration or increase of metal powder in the lubricating oil is found, it should be replaced or filtered in time to avoid the lubricating performance of the lubricating oil from being degraded due to oxidation, and to avoid the small particles falling off during the drawing metal particles damage the mold.

4. Regular maintenance and repair of drawing dies

In the process of long-term use of the wire drawing TC dies, the die wall is subjected to strong friction and erosion of the metal wire, which will inevitably produce abrasion. The most common one is the annular groove (dent) at the wire entrance in the working area.
If it is not replaced in time for repair, the ring groove will continue to expand rapidly, making repair more difficult, and there may even be cracks in the deeper part of the ring groove, causing the mold to be completely broken and scrapped.