industry news, news 07/07/2026 0
The surface galvanizing technical flow for zig zag wire is a multi-stage process designed to apply a uniform, adherent zinc coating for corrosion protection, building upon the precise geometries achieved through prior cold bending or hot rolling production steps. This flow ensures the coating integrity is maintained across the entire complex profile, including bends and arc transitions, without filling gaps or altering the wire’s dimensional tolerances.
Effective galvanizing begins with meticulous surface preparation. The formed zig zag wire first undergoes degreasing to remove oils and drawing compounds from manufacturing. This is typically done in an alkaline cleaning bath, followed by thorough rinsing. The next critical step is pickling, where the wire is immersed in a heated hydrochloric or sulfuric acid solution to dissolve mill scale, rust, and any remaining oxides, revealing a chemically clean, active steel surface. For some alloy steels, an additional fluxing stage follows, involving immersion in a zinc-ammonium chloride solution. This flux layer prevents re-oxidation before galvanizing and promotes optimal zinc wetting and adhesion during the coating process. The configuration of the zig zag wire—its bends and pitch—requires careful racking or basketing to ensure all surfaces, including internal angles, are fully exposed to cleaning and pickling solutions without allowing wires to nest together, which would create uncoated contact points.
The pre-treated wire is then immersed in a molten zinc bath, maintained at a temperature between 440°C and 460°C. The immersion time is precisely controlled based on wire diameter and steel chemistry to allow for the proper metallurgical reaction between iron and zinc. As the wire enters the bath, the flux layer vaporizes, and the clean steel surface reacts with the molten zinc to form a series of zinc-iron alloy layers, topped by a layer of pure zinc. For zig zag wire, the entry and withdrawal angles and speeds are carefully managed to allow molten zinc to flow freely over and off the complex profile, preventing excessive buildup on lower bends or the formation of drips and runs that could create uneven coating thickness or bridge gaps in the pattern.
Following withdrawal, the wire passes through a centrifuge or is vibrated while the zinc is still liquid. This step, crucial for open profiles like zig zag wire, uses centrifugal force or vibration to shed excess zinc from the surface, ensuring a smooth, uniform coating and preventing the bends from being fused together by solidified zinc. The wire then moves to a controlled cooling area. Cooling must be gradual and even to prevent coating cracking due to differential thermal contraction between the steel core and the zinc coating, a risk heightened at sharp bend points.
Once cooled, the galvanized zig zag wire undergoes rigorous inspection. Coating thickness is measured at multiple points, including on the straight segments and at the apex of bends, using magnetic or electromagnetic gauges. The specification typically requires a minimum average thickness, with particular attention paid to ensuring the coating at the bends—where stress is highest—meets or exceeds this minimum. Adherence is tested via standard methods like the Preece test (copper sulfate dip) or a more rigorous quench test, where a sample is rapidly cooled in water to check for coating flaking.
The final visual inspection checks for coating continuity, smoothness, and the absence of defects such as bare spots, ash inclusions, or gross dross particles. The wire is also checked for any distortion or dimensional change that may have occurred during the thermal cycle of galvanizing. The completed product is a zig zag wire with a continuous, protective zinc coating that follows every contour of its profile, providing long-term corrosion resistance suitable for outdoor, industrial, or harsh environment applications while preserving its precise mechanical geometry.