Zinc Burn-Back When Welding Galvanized Strip
Galvanized coil saves a post-plating step, but welding it burns the zinc at the seam and leaves a grey, corroded line that buyers reject. Mills that overheat the weld zone also clog tooling with zinc fumes, shortening roll life and raising maintenance.
Why Galvanized Strip Burns at the Weld
Zinc vaporizes at a much lower temperature than steel, so an unguided or over-driven seam overheats the coating and leaves wide burn-back. Without fast, even cooling the heat spreads along the body and dulls the coating, while zinc residue abrades unprotected roll surfaces.
The ZY20 Galvanized Tube Mill Solution
Dedicated seam guidance and adjustable squeeze pressure keep the weld zone narrow, limiting zinc burn-back to a thin, controllable line.
A 100 kW solid-state HF welder delivers stable, focused heat, and ≥10 t/h spray plus overflow-pool cooling quenches the seam before the coating dulls.
The line forms HR, CR and galvanized coil through the same pass, with 42CrMo hardened shafts and side-pull quick change for fast material switch-over.
Technical Specifications of the ZY20 Tube Mill
| Parameter | Specification |
|---|
| Tube outside diameter | φ10–26 mm |
| Wall thickness | 0.4–1.5 mm |
| Rated production speed | up to 90 m/min |
| Raw material | HR / CR low-carbon steel, galvanized steel |
| HF welder power | 100 kW solid-state |
| Forming stands | 5 rough + 3 finish |
| Sizing stands | 6 horizontal + 6 vertical |
| Leveling rolls | 7-roll precision leveler |
| Cut length / precision | 4–8 m, ±3 mm |
| Coolant flow | ≥10 t/h spray + overflow pool |
| Roll shaft material | 42CrMo quenched & tempered + HF hardened |
Complete Continuous Production Process
Every ZY20 runs one continuous flow from coil to finished cut tube. An uncoiler feeds strip through a 7-roll precision leveler that removes coil-set, then double-radius forming shapes it in 5 rough and 3 finish stands without edge wave. A 100 kW solid-state HF welder fuses the seam under squeeze pressure with a dedicated seam guide, and an automatic outside-burr unit clears the bead immediately. ≥10 t/h spray plus overflow-pool cooling locks the shape, the 6-horizontal + 6-vertical sizing train sets the diameter, and a 4-roll Turk head straightens the tube before the microcomputer flying saw cuts 4–8m lengths to ±3mm. Overload-protected stands and 42CrMo hardened shafts keep the whole line stable over long runs.
Where the ZY20 Galvanized Tube Mill Is Applied
Galvanized light construction, greenhouse framing, fence and guardrail tube, and any φ10-26mm zinc-coated section that must skip a separate plating step.
How to Select a Galvanized Tube Mill
Confirm your coil is galvanized and note the coating weight, then match OD and wall to φ10-26mm / 0.4-1.5mm. Verify cooling capacity and seam control for minimal burn-back, and size utilities for your speed.
Installation, Support and After-Sales
The ZY20 ships as a turnkey package with layout and foundation drawings so you can prepare the site before delivery. Engineer-led on-site installation and commissioning bring the line to rated output, with operator training to hand over a running mill. A one-year warranty with spare-parts support protects the investment, and because the line accepts HR, CR and galvanized coil, you can adapt to changing material costs and market demand without re-tooling.
Frequently Asked Questions About the ZY20 Galvanized Tube Mill
Will the zinc coating survive welding?
Yes — narrow seam guidance and fast cooling keep burn-back thin and controllable.
Can I switch between galvanized and black steel?
Yes, the same pass handles HR, CR and galvanized coil with quick roll change.
How is tooling protected from zinc residue?
42CrMo hardened shafts and rapid-cooling design reduce zinc build-up and wear.
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