Steel slitting stands as a crucial process in the metal supply chain, offering the means to tailor large steel coils into narrower coils or strips. This customization enables steel suppliers to meet the specific strip width requirements of end-users across various industries, ranging from construction to appliances and automotive manufacturing. In this blog, we delve into the basics of steel slitting and explore how it brings benefits to both metal producers and consumers.
WHAT IS STEEL SLITTING?
Steel slitting involves the process of cutting wide steel coils lengthwise into multiple narrower coils or strips. This method emerged as an efficient alternative to time-consuming and labor-intensive metal slitting techniques, such as band saws or cut-to-length operations. With high-speed steel-slitting lines, steel suppliers can process materials more quickly, providing slit coils and sheets in a more cost-effective manner.
HOW DOES METAL SLITTING WORK?
During the slitting process, a steel coil is loaded by crane onto a decoiler, which then feeds the coil into the slitting line. As the coil advances through the line under tension, rotary slitting blades precisely slice the width into the required strip widths and gauges. These blades cleanly cut the steel from edge to edge, minimizing material loss.
Following the slitting, the coil may undergo processes such as edge-trimming, leveling, recoiling, or cutting to length. The final slit steel output is typically packaged and shipped to customers. Depending on the application, common slit widths can range from 1/2 inch up to 60 inches, with slitting lines accommodating steel coils up to 1/4 inch thick and over 60 inches wide.
SLITTING EQUIPMENT Various types of metal slitters are available, ranging from single-shaft equipment to high-volume, multi-shaft slitting lines, each with its own advantages and limitations. The most common machines used today are high-speed steel razor slitters, known for producing clean and accurate slit edges, even on high-strength steels.
Here are a few main types of slitting equipment:
- Slitting Saws: Circular saws with hardened teeth, ideal for shorter runs.
- Rotary Shear Slitters: Rotating blades utilizing a scissor-like shearing action to cleanly slit the coil through, leaving no residual saw teeth marks.
- High-Speed Steel Razor Slitters: Carbide blocks with razor blades attached, providing precision at high speeds and a smooth edge finish. Most modern lines utilize razor slitters.
TYPES OF SLITTING STYLES
The two primary styles of slitting are longitudinal and crosscut slitting. Let’s delve deeper into these two types.
LONGITUDINAL SLITTING This method is most common for coil processing, involving the cutting of wide coils into narrower strips in a continuous manner. The cutting direction is parallel to the length of the original metal coil. The end product is narrow strips or coils used in various applications, including roofing, construction, automotive components, and more.
CROSSCUT SLITTING Crosscutting allows the slitting of sheets into smaller sheets or strips. The process involves cutting wide sheets or coils into shorter lengths, creating individual pieces. Here, the cutting direction is perpendicular to the length of the original metal coil. The end product is individual sheets or smaller lengths of material, often used for packaging, manufacturing smaller parts, or applications requiring shorter pieces of material.
BENEFITS OF SLITTING Several key benefits differentiate slitting of steel coils and sheets from other methods, including enhanced efficiency, precision, and cost savings.
- COST SAVINGS: Slitting is a continuous operation that proves more cost-efficient per pound than cutting sheets from a shear. Slitting a wide coil on a high-speed line is equivalent to multiple cuts from a sheet shear or sawing operation, where labor, time, and consumable blade costs accumulate.For instance, slitting a 40,000-pound coil into ten slit coils takes less than an hour, whereas shearing 40,000 pounds of sheets would require 8-10 hours or more, wearing shear blades faster in the process.
- CUSTOMIZABLE: Slitting empowers steel suppliers to produce coils and sheets in custom widths based on customer needs, minimizing the need for additional processing. Instead of purchasing a standard width sheet, slitting allows for custom widths tailored to specific parts or roll-forming applications.
- PRECISION TOLERANCES: Modern high-speed slitting lines with razor slitters can maintain extremely tight width tolerances. This precision allows steel to be directly used in automated stamping presses or CNC machining centers with minimal secondary processing. Additionally, slit-edge squareness of under .010″ per inch of coil width is standard, enabling customers to stamp or form parts to close tolerances across the strip width.
- CLEAN SURFACE FINISH: The smooth, clean-sheared edges achieved through steel razor slitting provide a superior surface finish without deformation from mechanical sawing or teeth marks, as would be caused by a slitting saw or bandsaw. This surface finish integrity permits the use of thinner gauges and helps maintain corrosion resistance.