The Basics of Coil Processing, Part 1: Unwinding the Coil

The inline design proves particularly useful for threading heavy-gauge material, since the leading edge of the coil enters the pinch rolls close to the nest rolls. A disadvantage of this style: Access to the nest rolls typically is blocked, requiring coil loading from the top with an overhead crane or lift truck.

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The third type of cradle—a cradle-feeder straightener (CFS)—unwinds, straightens and feeds directly into the press without the need for a slack loop, making it a very compact and self-contained coil-feeding system (Fig. 2). A CFS typically receives power from one or more closed-loop servo drives, and pays off from the bottom or top of the coil. This style provides the same advantages as the inline style, but allows the use of a loading ramp for quick coil changes. Because this style requires that coil feeding start and stop in unison with the feed motion, a CFS requires significantly more horsepower than the other cradle styles, which feed into a slack loop and unwind in a continuous operation.

Due to the vastly increased load, a CFS typically is limited to slower-speed applications, and may prove more costly than the other cradle styles due to the use of high-power servo drives. Additionally, the CFS concept generally is not recommended for use with long progressive dies, since a CFS does not allow for an effective pilot release unless the entire straightener bank is piloted.

Centering/Horizontal Reels

The second type of coil unwinder, known as a centering or horizontal reel, is the most common and versatile used by metalformers. These setups hold the coil by its inside diameter over an expanding arbor assembly that grips the coil’s inside diameter. Reels prove ideal for light- to medium-gauge material or for nonmarking applications, since their designs avoid contact with the outer wraps of the material as it unwinds. However, reels also can be used for heavy-gauge or high-strength materials if outfitted with the necessary equipment to safely contain coil clockspring and assist the threading operation.

Coil reels come in powered and nonpowered versions. Powered reels—motorized with a loop control for payoff into a slack loop—find use in applications that don’t require straightening, although they also can be used with a pull-through straightener powered by a feeder at the press.

Nonpowered reels, also known as pull-off reels (Fig. 3), typically feature only a small fixed-speed threading drive or, in some cases with smaller coils or light gauge material, no drive at all. Pull-off reels rely on a power straightener or a set of pinch rolls to pull the material off of the coil during automatic operation. These reels typically feature a drag-tensioning device to maintain back tension, preventing loop slack and material distortion.

Reels come in numerous configurations, the most common being a single-mandrel cantilevered style. These typically are offered in capacities from 500 to 60,000 lb., in widths to 78 in. Metalformers can opt for stationary or traveling models—a traveling reel can quickly be repositioned upon detection of misalignment.

Another version of the coil-reel concept is the double-ended version (Fig. 4), featuring two mandrels facing in opposite directions, with a rotating head. This style suits applications requiring quick coil changes, since the empty mandrel can be reloaded with a fresh coil while the other mandrel runs. With the addition of dual-holddown arms, double-ended reels also gain favor for running partial coils.

Yet another option is the dual-cone or double-stub-arbor version, typically used only for very wide coils or for heavy coils with small inside diameters. Here, a mandrel is inserted into both ends of the coil for support. This style, however, can carry a high purchase price, as the metalformer basically must purchase two complete traveling-reel assemblies with stubby mandrels.

Pallet Decoiler/Pan Reel

The third type of unwinder is the pallet decoiler, or pan reel. This style typically finds use only with coils of narrow, light-gauge materials. Using this style, the metalformer lays the coils on their sides and stacks them on a pallet placed on a motorized turntable for unwinding. The top coil runs first and when complete, the next coil in the stack can immediately be threaded without actually having to load a coil. The range of material width and thickness is limited, since the strip must make the transition from vertical to horizontal as it unwinds.

See also: Coe Press Equipment Corporation

From the basic slasher system technology of yesterday to the advanced, fully automated coil warehouses of today, new technologies have revolutionized metalforming. With the rising popularity of metal in construction projects, including walls and roofs, contractors are leveraging various levels of automation to manufacture materials in-house and improve their operations.

Layers of automation include:

Manual systems: Manual systems require operators to handle all aspects of coil processing, from positioning slitting knives to measuring and cutting materials. While cost-effective for small-scale operations, these systems are labor-intensive and prone to human error.

Semi-automated systems: Semi-automated systems balance affordability and efficiency. These systems automate repetitive tasks, such as knife positioning and job tracking, while allowing workers to oversee operations with minimal training. They are ideal for mid-sized contractors to scale their operations without significantly increasing overhead costs.

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Fully-automated systems: Fully automated systems handle everything from coil storage to cutting and slitting, reducing manual intervention to a supervisory role. Features such as enterprise resource planning (ERP) integration allow seamless job transitions, often taking less than two minutes. Though costlier, fully-automated systems deliver efficiency and scalability, enabling contractors to meet varying customer demands rapidly.

The evolution of coil processing

How did we get here?

The origins of coil processing in the architectural sheet metal market date back to the late s. Initially, only large manufacturers with significant financial resources could afford the equipment. These systems allowed these companies to capitalize on bulk purchasing and
in-house processing, but the high cost put them out of reach for smaller contractors and regional manufacturers.

Making coil processing accessible

In , the industry saw a breakthrough with the introduction of more affordable coil processing solutions. This dynamic began to shift with the first slit-to-width and cut-to-length machine, which met customer demands at a price point appropriate for a broader audience. Priced at approximately $50,000, this equipment opened doors for mid-level manufacturers and regional businesses. Contractors gained the ability to control inventory, produce on demand, and customize materials.

The rise of automation

The mid-s ushered in the era of semi-automated systems. These systems automated previously manual tasks, such as positioning slitting knives and tracking job specifications. Software integration further enhanced efficiency by optimizing material usage and streamlining processes.
Contractors could download job specifications directly into control systems, reducing errors and labor-intensive adjustments.

Between and , fully automated coil warehouse systems revolutionized the industry. These systems automated slitting knife adjustments and managed coil storage and retrieval. Additionally, coils could be loaded into a warehouse, remaining untouched until processed. Automated systems selected and staged coils based on job requirements, significantly reducing non-value-added movement and potential damage. Additional features, such as film application and barcode labeling, streamlined downstream processes and improved traceability.

Challenges and benefits of in-house coil processing

The transition to in-house coil processing brings challenges, including:

• Space requirements: Companies must reevaluate their raw materials storage requirements and allocate space for the new equipment.
• Skillset advancements: Advanced systems require training and operational adjustments.
• 
  Initial investment: While now more affordable, advanced systems still represent a substantial investment.

If companies make these changes to their processes, the benefits are significant:

• Cost savings: Contractors can reduce material costs by processing coils in-house rather than purchasing
  pre-cut sheets.
• Operational flexibility: On-demand production reduces dependency on external suppliers and enhances scheduling efficiency.
• Improved jobsite control: Materials can be produced to the exact specifications needed in a timely fashion. This flexibility reduces delays and ensures mistakes are corrected quickly, preventing
  project disruptions.
• Increased revenue opportunities: Contractors can diversify their services by supplying processed materials to other businesses.
• 
  Inventory control: A single master coil can serve multiple purposes, simplifying inventory management. Smaller coils can reduce storage challenges and align with existing equipment capabilities, such as forklift capacities.

Why coil processing performance matters

Effective coil processing starts with quality materials and a reliable supplier with a solid reputation. Purchasing in bulk allows contractors to negotiate costs down to fractions of a penny, which can make a significant difference at scale. A good supplier relationship may include inventory management support, such as holding stock for contractors to save shop space.

Contractors must consider their current processes and decide whether to mimic existing practices or implement new ones. For example, transitioning from purchasing flat sheets to processing coils in-house requires robust straightening systems to ensure flatness. Protective films may also be necessary to prevent damage during storage and handling, with different options suited for various materials.

In-house coil processing eliminates unnecessary steps, such as transporting materials between multiple stations. Systems with adjustable slitting knives and efficient stacking solutions can streamline operations, reduce material handling, and enable just-in-time production.

Automation and sustainability

Technology in coil processing continues to evolve, with hybrid systems bridging the gap to reduce costs and make automation more accessible. Customizing materials on demand offers unparalleled control over job timelines and reduces reliance on external suppliers. Automation ensures contractors can adapt to economic fluctuations while meeting sustainability goals through optimized material usage and reduced waste.

Advanced systems also support sustainability initiatives by minimizing overproduction and excess handling. Contractors increasingly recognize the importance of having the right materials—precisely when needed—to ensure project success.

Coil processing and automation have transformed the metal construction industry, offering cost savings, operational efficiency, and business growth opportunities. By bringing processes
in-house, contractors gain control over their projects, reducing delays and improving job site adaptability.

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