Aircraft parts maker automates fabrication.
In addition, the cell and its computer control system can produce small batches more economically, respond more quickly to specification changes, use a higher percentage of each sheet, and process orders more rapidly than previously possible, according to Dick Estes, general manager of the facility.
Brought onstream early this year, the 100,000-sq-ft plant now produces a wide variety of cut, drilled, and formed parts for fairchild civilian and military aircraft (Figures 3 and 4), and also for aircraft built by other manufacturers. Later, when the plant has been more fully equipped, Fairchild plans to market fabricated parts to other industries such as appliance and electronics manufacturers.
The fabrication cell is the first in a series of flexible manufacturing cells planned for the facility. As funding and technology become available, cells for automated bending and forming--as well as additional cells for routing and drilling--will be added.
About 156 different alloys and gages of aluminum sheet are now being cut. The sheets range from 0.016" to 0.200" in thickness, and up to 48" X 144" in size. Several sheets at once
Material brought into the plant is stored flat. When called for by production scheduling, the sheets are moved into a staging area where they are stacked vertically.
Upon demand, an operator uses an overhead, underriding crane to transfer the sheets to a straightener and then to a 1/4" X 12-ft capacity hydraulic shear from Cincinnati Inc, Cincinnati, OH. Here sheets of identical material are cut to the uniform size required for a production nesting order.
The operator then places a 1/4"-thick baseplate (always wider than the sheets to be routed and drilled) on a cart, and stacks the uniformly cut aluminum sheets on the baseplate. The nest thus formed usually totals 1/2" in depth.
The operator then manually clamps the cut sheets and baseplate together, and drills a series of about eight holes along one edge of the stack. He inserts pop rivets in the holes, securing the sheets to the baseplate.
The operator then removes the manual clamps and, using a cart, wheels the nest to the custom-built nest storage and retrieval rack. The first unit in the flexible fabrication cell, this rack can hold up to 12 assembled nests.
When called for by the computer-based production schedule, an extractor automoatically pulls the required nest from the rack, tilts it, and transfers it to the CNC routing and drilling machine provided by Trumpf America Inc, Farmington, CT. Hydraulic clamps at the top of the machine's infeed table automatically secure one end of the nest.
The CNC routing and drilling machine (Figure 6) has 6 spindles holding 4 drills, 1 router, and 1 riveter. Motors for the drill heads are 5-hp, 18,000-rpm, aircooled units; drill shank diameters range up to 0.413". The routing head has a 12-1/2-hp, 14,000-rpm motor; this spindle can handle routing cutters from 0.236" to 1.000" dia.
After the nest has been automatically clamped and positioned under the spindles, the machine drills a series of holes along one edge of the nest. The riveter then positions and drives rivets into these holes, ensuring that the sheets will not shift within the nest during the machining cycle.
Next, the machine drills and routs according to a nesting program, generated with software from Camsco Inc, Richardson, TX. Programmed on a Model 1000E computer from Hewlett-Packard, Palo Alto, CA, the nesting program is first uploaded to the plant supervisory computer (see Figure 5), a Model MV 4000 from Data General Corp, Westboro, MA.
This computer download APT-generated CL (cutter-line) files to the Trumpf machine's Vega CNC controller. Provided by Vega Servo-Control Inc, troy, MI, the controller contains a built-in postprocessor that converts the nesting-program data directly into machine commands. Separation is manual
Drilling and routing completed, the Trumpf automatically drills out the rivets that hold workpieces, and then discharges the machined nest to an unload cart. Using a small jib crane, the cell operator transfers the nest to a flat table. Here he manually removes the cut parts from the nest, placing them on one of two belt conveyors leading to degreasing and deburring equipment. He is aided in this by a CRT display that shows--in color outline--the parts to be handled.
Separating the cut parts from the nest's skeleton or lattice, and handling the skeleton and baseplates, occupy about 20 percent of the operator's time. He spends the balance of this time in monitoring the cell's automatic material handling and machining, and in watching for tool wear and malfunctions.
Parts larger than 8" in the long dimension go onto a belt conveyor feeding a Model WB-300 unheated belt washer from Detrex Chemical Industries, Detroit, MI. These parts then pass on an intermediate belt conveyor to a Somaca Model FSD-6364 flat-part deburring machine from Sommer & Maca Industries, Chicago, IL. Belt speeds through the degreaser and deburring machine can be set between 5 fmp and 12-1/2 fpm.
Parts smaller than 8" are placed on a second, parallel conveyor that carries them to manual degreasing and deburring machines. This is done because the three brushes in the deburring machine would upend the smaller parts, flip them around, and not accomplish the required deburring. The stray parts might also jam the conveyor
At the discharge end of the cell, the parts drop into trays dispensed from an automatic, custom-built dispenser. Each tray bears a paper label imprinted with a bar code and man-readable symbols.
A bar-code scanner from Scope Inc, Reston, VA, reads the bar code and relays it to the supervisory computer. One of this computer's files maintains a cross-index between part numbers and tray numbers.
Bar-coded trays of parts then go into a STAK manned storage and retrieval system from Stanley-Vidmar, Allentown, PA. Here an operator uses a manually operated hydraulic lift to pick and place trays in two parallel racks. Fairchild plans to eventually automate this storage and retrieval system.
From rack storage, trays of parts may go to one or more of several stations for additional processing. One of these is a bending station comprised of two CNC hydraulic press brakes--one a Model 90, the other a Model 135--from Cincinnati Inc, Cincinnati, OH. This cell is now manually operated, but may eventually be automated with vision-aided robots.
Another station centers around a Quintus Model QCF fluid-cell (bladder) press from ASEA Inc, White Plains, NY. Rated 500 psi to 14,500 psi, the press shapes parts by compressing them between a neoprene cell or bladder filled with liquid and a set of machined metal forms accurately placed in the press bed. Fairchild recently bought a five-axis CNC machining center to make forms for the press. (For more on fluid forming, see "Drawing complex shapes: High-pressure fluid forming pays off," in our Sept 1983 issue.)
Other processing units now in place and operating include heat-treat furnaces, freezers, and chemical-treating tanks. Sponsored by Air Force
Development of the flexible fabrication cell and its control system was carried out by the Cleveland, OH, office of Booz * Allen & Hamilton Inc, New York, NY. Direction of the 27-month program was handled by Charles Skinner, vice president; Paul Takacs, program manager; and engineers John Lambert and Ted Caridi. Implementation at the site was supervised by Dick Estes and by Frank Jack, project manager.
Sponsor of the $2.7-million contract for analysis, design and engineering was the Intergrated Computer-Aided Manufacturing (ICAM) Office of the US Air Force's Systems Command, Wright-Patterson Force's technical director for the project was Lt Kenneth Lillie.
The plant and all its standard equipment and software were purchased directly by Fairchild Industries. Custom-designed modules were funded by the Air Force.
Motivation for the program came primarily from the Air Force. Recently, a joint study by the Air Force and the Boeing Airplane Co, Seattle, WA, revealed that over 85 percent of the labor costs in aircraft production stem from fabrication of small metal parts. Reduction of the costs in this labor-intensive function will benefit American taxpayers as well as the aircraft manufacturers.
Fairchild Industries has estimated that the cell and its computer controls can pay for themselves in one to two years with three-shift operation, or in three years with two-shift operation. Currently the plant is running one shift only. The need to boost volume and achieve payback is one of the reasons for Fairchild's marketing efforts among other aircraft manufacturers and in the appliance and electronics industries.
Since the technologies involved were developed and implemented under Air Force ICAM sponsorship, they can be acquired by interested US companies. Copies fo initial and interim reports on the program and system are available from Lt Lillie. His telephone number at Wright-Patterson AFB is 513-255-7371.
In addition, details on the flexible fabrication cell may be obtained from Charles Skinner at Booz * Allen & Hamilton Inc, Cleveland, OH. His phone number is 216-524-5900.
For literature on the equipment and software now in the plant, see the box. Information on fabricated metal parts from the Fairchild plant may be obtained by writing to: Dick Estes, General Manager, Fairchild Precision Fabrication Center, PO Box 7545, 4800 Cargo Drive, Columbus East Industrial Park, Columbus, GAS 31908. The phone number is 404-568-6586.
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|Author:||Quinlan, Joseph C.|
|Publication:||Tooling & Production|
|Date:||Jun 1, 1984|
|Previous Article:||Machine vision to serve flexible systems.|
|Next Article:||Management's midsection.|
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