Why Do Tungsten Carbide Wire Drawing Dies Fail?
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Why Do Tungsten Carbide Wire Drawing Dies Fail?
In the production of steel wire, the consumption of wire drawing dies can be cracked or worn. Cracked molds can only be scrapped. Worn molds can be repaired and reused. Therefore, the proportion of die cracking should be minimized in production. Today I will talk about the fracture and wear forms and maintenance methods of the tungsten carbide wire drawing dies.
Statistics show that the core rupture has the following three forms:
- Longitudinal ruptures. 75% of the broken dies are longitudinal ruptures, 90% of which are normal damage caused by the thinning of the core wall after repeated grinding, and only a small part is due to the excessive drawing reduction rate and the oxide scale on the steel wire surface is not cleaned, poor coating and poor mold mounting.
- Transverse ruptures account for about 13% of the total. Transverse ruptures are mainly caused by poor mold mounting, such as excessive core taper or out-of-roundness, and poor contact between the core and the bottom surface of the casing.
- Cracks and chipping at the outlet side accounted for 6% respectively. Dies material defects and improper wire drawing techniques accounted for half of them. Chipping was mainly due to mold quality problems.
There are also 3 manifestations of the wear of the inner hole of the drawing die:
- Rough surface.
The deformation heat generated by the wire drawing causes the temperature of the mold to rise, and local oxidation color appears, causing slight wear. Poor lubrication leads to spot welding between the steel wire and the die hole surface, the tungsten carbide particles loosen, and the displacement forms scratches and corrugations. The surface of the working cone and the bearing land is rough and has a lot of wear.
- Oval wear.
The hardness of cemented carbide is uneven, the drawing direction does not coincide with the axis of the die hole, and excessive force on one side of the die hole will cause elliptical wear.
- Annular groove-like wear is typical wear caused by overuse.
During the drawing process, the die hole continuously bears the impact of the wire, which loosens the tungsten carbide particles and forms a rough surface. The rough surface scrapes off the metal chips from the surface of the steel wire, which deteriorates the lubrication condition and accelerates the wear rate. Finally, an annular groove is formed in the area where the die hole bears the greatest impact force.
From oxidation to discoloration to rough surface to the appearance of ring grooves is a process of increasing wear. Reasonable use of dies, the way to extend the life of the die is to grind it in time and replace the dies before the annular groove appears in the inner hole. The TC wire drawing dies should be cleaned and inspected in time after each use. If the surface is slightly worn, it can be directly polished or finely ground and used as processing dies after polishing. Try to control the amount of die grinding to the minimum level and increase the number of die repairs and reuses. According to GB/T 6110, when the diameter of the die hole is close to the maximum diameter of the die blank of this size, more attention should be paid to the surface of the die hole, even if there are slight lines, it must be scrapped to prevent steel wire waste. The life of the die is usually measured by the number of meters or the quality of the steel wire drawn when the wear is 0.01 mm. For the medium-sized (4.0 mm diameter) special steel wire, the lifetime value of the cemented carbide die can generally reach 300,000 meters/0.01 mm above. Mold consumption is usually expressed by the mass of hard alloy mold core consumed per ton of steel wire. The mold consumption index of special steel wire is about 150-250 g/t.
As a professional tungsten carbide wire drawing dies manufacturers, we sell drawing dies to more than 30 countries and win customers' positive feedback. If you do detect a drawing dies failure, look for clues, but don't stop with everything you see in front of you. Contact us for more solutions.
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