Trim Conveying & Pneumatic Material Handling

Handling System Provides A Perfect Fit

Double Eagle Coating Co. squeezes out a cost-effective solution to safely meet its trim handling needs.

When faced with the problem of finding the safest and most cost-effective way to handle the sharp-edged scrap produced from its new side trimmer, Double Eagle Steel Coating Co. in Dearborn, Mich. Turned to Quickdraft of Canton, Ohio.

“We were facing a major problem with handling trim from the new side trimmer at our coating line,” says Raymond J. Dykstra, engineering manager at Double Eagle. “Space was extremely limited; safety was a major concern; and our budget wouldn't allow for handling the scrap multiple times with manpower.”

Before going to Quickdraft, Dykstra researched alternatives with Ed Gilliland, project manager from Capital Engineering Inc. of Hammond, Ind., and other from Double Eagle. The traditional systems fell into two categories: mechanical conveyors and airborne conveyors. In either approach, the trim from the coated steel was chopped into manageable pieces.

With the mechanical conveyors, the pieces would have to be loaded onto the conveyor by some means and then the conveyor apparatus would have to be routed through the plant to some location where the scrap could be gathered for disposal.

At this particular coating line, transferring the pieces from the choppers to a conveyor belt was not economically feasible. Moreover, there was insufficient space to construct a conveyor properly.

Airborne conveyors were studied in depth. The trim scrap could be captured at a reasonable cost but trenching would have to be provided for a considerable distance. That cost was excessive but of even greater concern was the routing. The conveyor would have to go through an existing power substation. This would have created an undesirable situation whereby production equipment would reside in a restricted area requiring access by unauthorized personnel for performing regular maintenance.

Pinpointing concerns

All of the approaches examined had significant shortcomings in safety and environmental factors. Containing the sharp-edged scrap, for example, was a major concern. Extensive and costly safety measures would have to be taken to ensure that the pieces did not escape their confines and that personnel did not get entangled with the conveyors.

The zinc dust from the coating created by the trim scraps was another concern for Double Eagle. Thus the company's planning for traditional trim handling methods included provisions for a dust collection system.

In the course of his extensive analysis, Dykstra came across some aluminum product applications of pneumatic conveying which had been successfully engineered by Quickdraft, an engineering company with more than 35 years of expertise in the field.

“Quickdraft is preeminent in pneumatic conveying for paper, film, foil and metals such as aluminum. They have a great track record with companies such as Champion International, Reynolds Metals, DuPont and Allegheny-Ludlum,” Dykstra explains, “but they hadn't done a project with the specifications we required.”

After evaluations, simulated tests of the system at Quickdraft's Canton plant, and even visits by Double Eagle employees to other companies which utilized systems developed by Quickdraft, Double Eagle decided to purchase the newly designed system from Quickdraft.

The system's innovative “push-pull” design is the basis for the smooth operation of Double Eagle's trim handling operations. Trim from the galvanized sheet steel is chopped into 7-in. long pieces. These drop into a specially engineered hopper over an ejector.

A powerful fan upstream of the ejector provides the motive force to “push” the pieces into a vertically inclined duct rising approximately 50 ft. and penetrating the outside wall of the mill. The duct continues in a horizontal plane through a Quickdraft eductor and then into a filtered knock out receiver.

“Push-pull” design

A turbo unit injects air into the plenum of the eductor which creates a vacuum sufficient to “pull” the pieces through the vertical rise and through the eductor into the receiver.

At the receiver, the air and material are separated and the material is directed into a chute. An automatic diverter assembly is furnished in the chute so that the scrap material can be deposited into either of two trailers. Special provisions are made to spread the loading evenly. When a trailer is filled, it can be driven away while the trailer in the other bay is being loaded. No material handling is required.

Since the air is filtered at the receiver, the airborne dust particles created in trimming and chopping the coated steel are captured and controlled.

Dykstra and Capital Engineering's Gilliland acknowledged that there were some glitches—as could be expected in a project as innovative and extensive as this. Some design modifications were required along the way.

The system has been operational now for more than a year and Double Eagle is pleased with its performance. Dykstra and Gilliland cite the following as some of the most important features of the system:

• Safety: The entire process is either enclosed or contained, for maximum safety.

• Routing: The Quickdraft duct was installed vertically and overhead away from all other equipment in the mill. This was a major factor in restricting cost and installation time.

• Scrap handling: With this design, scrap is captured at the trim slitting point and conveyed directly to the scrap hauling trailers. Any other approach would have required two or three intermediate handling steps along with increased personnel costs and greater potential for accidents.

• Dust collection: Dust from the slitting and chopping operations can be a big concern in terms of contaminating the product, but the suction of the Quickdraft system captures most of the contaminants and filters them through the receiver. Otherwise, a separate dust collection system would have been required.

• Maintenance: The system is designed to minimize maintenance requirements and that has been the experience. A stand-by turbo blower unit was installed with the initial order as insurance for continuous operation. Both units continue to alternate, ensuring continuous operation with no special maintenance requirements.

The system has solved some vexing problems with trim handling for Double Eagle, and possible most important, the system had a role in the major cost reductions achieved by Double Eagle this past year by trimming product “on line.”