In a word, it was efficiency. People are constantly striving to find better ways to do things. They want everything to be bigger, stronger, faster, and more efficient. The pursuit of efficiency led inventive men and women to create the elevator, television, facsimile machine, 1.0-liter gasoline engine, and the Internet .

New generation continues quest for efficiency The metalworking industries are no stranger to the pursuit of efficiency. Gone are the day of easy profits and "cooperative competition." Today's "dog-eat-dog" approach to business is readily apparent. With fierce competition, the need for increased production efficiency is greater then ever.

Can pallet decoiling help in this quest for increased manufacturing efficiency? What does this new coil handling technology promise regarding efficiency in metal stamping and forming plants? When can pallet decoilers be used successfully? What are there limitations? This article will address these questions.

Pallet decoilers generally use some type of control point, ranging from front and side dancer arms to control slide drums, to actuate the drive system. In some instances, free-standing sensors are used.

Older versions of pallet decoilers were generally "on/of" styles that reacted to a microswitch on a dancer arm. Modern designs use some version of a variable-speed DC drive.

Pallet decoilers also offer what is generally considered to be a safe method of decoiling flat stock. Unlike traditional crane and "C" hook loading, no manual coil handling is required while loading a pallet decoiler. Back pain and abrasions are unlikely when coil loading is done from a forklift.

Misconceptions about pallet decoilers are common in metal-working plants. Many believe that these types of uncoilers can be used only for very narrow and/or thin material. Others believe that they are capable of operating effectively only at slow speed or light loads.

The new generation of pallet decoilers, however, is more versatile then are the older styles. Decoilers now on the market can handle material width up to 30 inches, although generally in thickness under 0.050 inch. Some decoilers can run stock as thick as 0.187 inch.

Some can handle speeds up to 400 feet per minute and quick-start roll forming lines. Still others designs can accommodate loads in excess of 25,000 pounds.

With traditional coil handling methods, a coil usually picked up off a coil stack either by a crane or a "C" hook. In some instances, a coil would be placed on an automated up-ender to turn the coil inside diameter (ID) horizontal. The coil would then be either be loaded onto a mandrel reel or be dropped into a coil cradle. Usually, changeover times for these procedures range from 5 to 20 minutes.

Other applications in which pallet decoilers may be useful include four-slide and cut-to-length operations, which have similar downtime and labor demands.

New technology such as specialized controllers and high-torque drive systems that some "high-end" pallet decoilers employ have increased their capabilities in demanding environments. For example, most consider that high-speed, clutch-driven roll formers with their immediate acceleration are too demanding for pallet decoilers. However, some pallet decoilers equipped with the new controls and systems can be used in such capacities.

An additional benefit for those running high-speed presses or mills is that some pallet decoilers can handle coils with outside diameters (ODs) as large as 80 inches, while many mandrels and cradles are limited to the typical 48- or 60- inch OD coils. The larger coils allow longer production runs between changeovers.

In some instances, the reduction in coil changeovers allows one operator to run several lines at once. One automotive supplier in Michigan, for example, uses pallet decoiling with all 12 of its roll forming lines in a new facility that has no mandrel reels, cradles, cranes, or up-enders. The company also increased coil ODs, began placing the coils at the lines rather than in a central storage area, and purchased new mill controls. Now, each operator runs two mills simultaneously, and production rates have jumped 400 percent.

Progress is also being made in paying off heavy-gauge stock from a pallet decoiler. This has always been the biggest drawback for decoilers, because thick strip tend to have a great deal of "clock spring." And it is difficult to turn flat. Some pallet decoilers now include features such as plane turners and coil containment systems to combat the problem.

Another potential drawback is space limitations. Some newer pallet decoilers no longer require a loop of material to properly decoil the stock. On lower-end models, however, a loop of material is still necessary for proper decoiling, possibly requiring more room than do reels or cradles.

Finally, applications in which the user is constantly banding and unbanding the coils for short production runs are not well suited for pallet decoilers. When various strip widths gauges are run alternately, double mandrel reels often provide quicker coil changeovers than pallet decoilers.

The decoiler should have properly rated acceleration and decel-eration times. This is the time needed for the platform to accelerate to full speed from a dead stop and to stop completely from full speed. If the decoiler does not have a quick ramp-up build into its controls, the system will fail to keep up with quick-start presses and mills. Conversely, if the decelerating time is inadequate, the decoiler will not stop quickly enough, and the coil stock will likely over-travel, creating other problems.

The horsepower required is inversely proportional to the acceleration/deceleration requirements. To illustrate, consider an application that calls for a 1-HP motor with a four-second acceleration/deceleration time. If the acceleration/deceleration time were increased 100 percent to eight seconds, the horsepower requirements would be reduced by 50 percent to ½ HP. Conversely, if the acceleration/deceleration time were cut in half to 2 seconds, the horsepower requirements would double to 2 HP.

A final consideration before buying is the type of drive with which the decoiler is equipped. Generally, electric (DC) and hyghdro-static drives are considered to be the quickest reacting. Pneumatic systems are rarely used because they are generally regarded too "jerky" and inconsistent for pallet decoiling.