Compact coil feed lines: small size, large impact

Compact lines help stampers save floor space, and they can also reduce tool wear and improve reliability.

Compact feed lines, developed more than 30 years ago, have become the new norm in metal forming. North American manufacturers are embracing this traditionally European technology, developed for multiprocess shops where floor space is at a premium.

In addition to floor-space constraints, application parameters play a role in determining whether a compact coil line is the right investment. Industry applications for these compact lines vary widely; however, the lines are especially important for high-volume users such as automotive and construction industries that depend on leveled, stress-relieved materials to produce a large variety of parts with high quality requirements.

High-volume part suppliers to OEMs find compact lines not only use floor space efficiently, they also are critical in lowering scrap rates and improving parts and overall equipment effectiveness (see Compact Line Helps Transform Tier 1). Because a compact line has fewer components and material does not have to travel as far as it does on standard, long-loop coil lines, it is likely that fewer disruptions will occur during the stamping process and the tools will wear less.

Standard lines are designed to handle a broad range of materials, from mild steel all the way up to advanced high-strength steel (AHSS) in various thicknesses and widths. However, these lines typically require a loop pit to create the necessary buffer between the continuously running decoiler, leveler, and the stamping press or the start-stop shear. This extends the length of coil and time required for the feeding process. A standard coil line also needs a precise loop design to avoid adding stress into the material, because leveling must be done just before the stamping operation so that the material quality is not affected negatively. The loop pit needs a foundation as well.

Small But Mighty

In contrast, a compact coil line does not need a loop and pit because the coil is mounted above the leveler and feeding mechanisms. A compact line has many of the same capabilities as a conventional line but occupies less floor space and, often, with simplified operation. Even at its small size—less than half the size of a standard line—it can handle thick and strong materials. These floor-space savers can process coils up to 20 tons with widths up to 59 inches (1,500 millimeters) and thicknesses between 0.031 and 0.47 in. (0.8 and 12 mm).

Multipurpose. In addition, compact coil lines generally are multipurpose machines: a combination decoiler, roller feeder, and leveler.

Tight Control. Additional features of compact lines are precise control of material tension upstream and downstream to control timing and material position and a pilot release system that prevents tool damage. The measuring wheel positions the coil strip into the stamping tool precisely, thus also preventing unwanted feeds and operating as a measuring slip to increase accuracy. As a result, the time for setup is reduced, as are decoiling and recoiling times.

Short Coil Change Times. Because a second coil can be placed on the machine while the first coil is engaged in feeding, rapid threading reduces coil change times to less than five minutes.

When Not Applicable

Some ultrahigh speeds (above 80 strokes per minute [SPM]) and unique materials such as prepainted and nonfoiled surfaces may not be a good fit for compact lines. However, stampers that are able to process materials within a compact line’s capacity will find them to be just the right size—not only for the shop floor, but also for the bottom line.

Photos courtesy of ARKU Coil Systems Inc.

Figure 1
TransForm Automotive provides transmission parts, such as clutch housings, clutch hubs, clutch drums, carriers, torque converter pistons, and assemblies, for major automotive OEMS.

Compact Line Helps Transform Tier1

TransForm Automotive, Sterling Heights, Mich., provides transmission parts for major automotive OEMS (see Figure 1). The Tier 1 stamping manufacturer produces clutch housings, clutch hubs, clutch drums, carriers, torque converter pistons, and assemblies.

The company introduced the roller die forming process to North America in 1997. The process uses tooling technology, developed in Germany, which consists of a full set of rollers located in the lower die set and a mandrel mounted to the upper die set. Its spline processing and geometry expertise are recognized throughout the powertrain engineering community. The company also has full prototype manufacturing and testing capabilities.

The manufacturer uses ARKU compact, multifunction coil processing machines to initiate tasks that involve high-end machine tools in the downstream operations, including in its high-volume processing lines in its London, Ont., Canada, plant. The London plant is on track to produce approximately 6.2 million parts in 2016.

According to TransForm Automotive Vice President Engineering Tom Meier, “The compact lines start everything [see Figure 2]. They are first in a line of press equipment worth millions of dollars. If the compact lines aren’t running, the other machines aren’t running either.”

With steel prices on the rise, TransForm Automotive relies on the material-saving capabilities provided by the zigzag traversing feeders. The manufacturer’s ARKU compact feed lines zigzag from side to side at 30 SPM. This optimizes material utilization, especially in the production of round punched parts.

Material optimization is just part of the bottom-line impact of the company’s compact lines. With fewer components in the coil line and decreased travel time of the material compared to a standard feed line, downtime has been reduced as well, Meier said. “The scrap rate is extremely low, but even more critical, the reliability is excellent,” Meier added. “We have annual downtimes of only about 30 hours between two compact lines. That’s an equipment availability of 99.9 percent.

“Elimination of the looping pit significantly increases productive space and frees up areas for additional machines,” Meier continued. “Our process reliability increased, as did our productivity. It’s also easier to operate, since the entire line can be monitored and adjusted from a single operator location [see Figure 3]. Adjustments can be made quickly and are immediately evident.”

Meier added, “These little compact lines really have had a huge impact on our business.”

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