GI Steel Coil Slitting Line

Shijiazhuang Faith Machinery Co.,Ltd designs and manufactures GI (galvanized iron) Steel Coil Slitting Lines that address the unique handling requirements of zinc-coated strip. These lines are engineered to preserve the integrity of the protective coating while delivering accurately slit coils for downstream forming, roll-forming, or fabrication processes.

1. Coil Handling and Decoiling
Each GI slitting line begins with a heavy-duty coil car and hydraulic mandrel decoiler, capable of supporting coils up to 25 tons. Mandrels feature low-friction, polymer-coated sleeves to protect the coil ID from abrasion and prevent zinc flaking. Automated coil loading sequences position the strip precisely, reducing operator intervention and ensuring consistent feed into the line.

2. Tension Leveling and Entry Protection
Before slitting, strip passes through a multi-bar tension leveler equipped with crowned and crowned-back rolls. This unit removes camber and residual stresses—common in galvanized material—while maintaining flatness. Entry guide rollers are fitted with polyurethane sleeves to avoid surface marking. Load-cell sensors upstream of the slitter maintain tension within tight tolerances, preventing coating cracks or micro-fractures along the slit edges.

3. Precision Slitting Section
The core slitting module features upper and lower rotary knives mounted on linear guideways. Knife holders use pneumatic quick-release clamps, enabling changeovers between slit patterns in under 45 minutes. Automatic knife gap control monitors slitting torque via strain gauges on the knife shafts and adjusts knife separation to maintain clean, burr-free edges without nicking the zinc layer.

4. Edge Brushing and Scrap Management
After slitting, optional soft-bristle edge brushing units gently remove loose zinc particles along the new edges, minimizing debris in the recoiled coil. Trimmed scrap is conveyed automatically to a shear-chopper assembly, which cuts waste into uniform lengths before collection in a central recycling bin, streamlining material handling and housekeeping.

5. Recoiling and Coil Build Control
Recoilers with V-belt or disc-type braking systems rewind slit strips at speeds up to 150 m/min. Transverse coil-centering guides and laser edge sensors maintain concentric winding, avoiding telescoping and ensuring even coil builds. Programmable coil wrap tension and speed profiles accommodate variations in strip thickness (0.15 mm to 2.0 mm) and width (600 mm to 1,600 mm).

6. Automation, Data Logging, and Maintenance
A Siemens-based PLC orchestrates decoiler, leveler, slitter, and recoiler drives, with an HMI that allows operators to recall material-specific recipes instantly. Key parameters—tension setpoints, knife torque, line speed—are logged to an SQL database for traceability and process optimization. Scheduled maintenance alerts, based on runtime and cycle counts for bearings and hydraulic components, help preserve line availability and coating quality over extended production runs.