Critical Factors Influencing the Quality of Wire Drawing Process

During the drawing process, it is common to encounter issues such as wire hardening, difficulty in drawing, high breakage rates, excessive streaks, and a limitation on the number of drawing passes, which pose difficulties for operation and result in production losses. There are numerous reasons for these problems, primarily due to the following factors:

1. Wire material quality

Surface quality issues such as ellipses, overlaps, shrinkage holes, spots, blemishes, and burrs all pose difficulties in stretching. Additionally, the inherent quality of the wire, such as its mechanical properties, chemical composition, and microstructure, significantly affect the quality of the product after wire drawing.

2. Rust Removal and Pickling

Wires are typically hot-rolled before being drawn, resulting in a surface with hard ferric oxide scale. The oxide scale can be divided into three layers: ferric oxide, ferrous ferric oxide, and magnetite. If not removed, it can easily damage the wire drawing die. Only after removing the oxide scale can the wire be drawn. Removal methods include mechanical rust removal, chemical acid washing, and electrolytic acid washing, among others. Poor handling can affect the drawing process.

3. Compression rate coordination

During the cold drawing process, the compression ratio is a crucial factor. Excessive compression increases deformation resistance and the required power, and it also tends to harden the wire material, leading to a higher rate of breakage. Generally, an appropriate compression ratio for wire drawing is around 20%-30%.

4. Lubricants and Cooling

During the stretching process, the addition of lubricant forms a thin film on the metal surface due to pressure within the working cone angle, preventing direct friction between the metal and the mold cavity. This reduces frictional forces, thereby lowering the equipment's power load and extending the lifespan of the wire drawing mold. However, it is crucial to lower the wire drawing temperature and ensure adequate water pressure to keep the mold in the carriage of the wire drawing machine wet. Poor cooling can lead to excessive wire temperature, damaging the lubricant and causing mold deformation and wear that affects the drawing process.

5. Winding Technology and Winding Speed Coordination

The rate of drawing speed, often referred to as line speed, should match the drawing process and cannot be increased blindly. If these issues are not properly addressed, merely increasing the drawing speed will not boost production; instead, it can damage equipment and molds, harden the wire material, resulting in poor quality and low yield.