March 2007 Edition

Aerospace Manufacturing

Nesting Isn’t Only for the Birds

A Brazilian aircraft maker was out in the cold when its CAM software supplier stopped doing business. It needed something better than a cookie-cutter solution

Nesting. Birds do it. Bees do it. Even aircraft makers do it. For airplane makers, it’s important to cut the maximum number of parts from sheet materials with a minimum amount of waste. Finding the right software to nest parts for cutting leads to increased efficiency and profit.

Empresa Brasileira de Aeronáutica S.A., commonly referred to as Embraer, is a Brazilian aircraft manufacturer producing commercial, military, and corporate aircraft and one of the largest aircraft producers in the world. Many U.S. airlines use Embraer commercial airliners on their feeder routes.

Market Research

With its headquarters and main manufacturing facility in São José dos Campos, São Paulo, the company is one of Brazil’s largest exporters.

Embraer’s original CAM system was purchased in the late 1990s to drive both its CNC routers and a Lectra conveyor knife cutter. After several years, the software company ceased trading, so Embraer set about evaluating several replacement systems. After detailed market research, it benchmarked five systems, one of which was from Jetcam International, Monaco. Embraer determined that for its applications, Jetcam was the most efficient of the five systems benchmarked for both composite cutting and sheet metal fabrication.

“Of the five systems tested, two could not generate better nests than our existing system,” Fernando Araújo, an Embraer manufacturing engineer, said. “When we approached Jetcam, we felt that they had an open approach to our further requirements.”

Programming Reduction by Remote Control

The system was installed in May 2004, and the composite programming was the first to be integrated to the Embraer system using Jetcam’s remote control processing – RCP – module. It reduced Embraer’s composite programming time by six hours across two shifts.

With the Jetcam system, Embraer has a single CAM system generating optimized NC code [G-code] for both routing and composite cutting on a Trumpf BFZ 3000 Router, a Creneau CNC Router, and a Lectra Vector 2500 conveyer knife cutter.

RCP automatically passes details on the parts to the Jetcam software, which then nests them using parameters set in Jetcam’s Stored Engineering Knowledge Technology – SEKT – database. The software then generates NC code and places it in designated directories ready for processing.

All of this takes place without a programmer performing any operation on a part or nest.

“In our old process, we had to select the orders to be nested, wait until they were nested, and sometimes manually redo a part or even the complete nest because the operator saw that it could be better optimized if made manually,” Araújo said.

“After that, the operator had to select another ‘pack’ of orders and do the same process again, spending all the day in front of the PC,” he said. “With Jetcam, the only time we spend is grouping the orders and generating the batch orders. After this, we press a button and come back later to get the results that are sent directly to the machine, without any rework.”

Embraer concentrated on optimizing and automating the composites first, due to the general manufacturing costs normally associated with them. With RCP in place and delivering savings, the airplane maker was surprised at the additional benefits that the free-form high-performance nesting – FFHPN – module provided.

No Empty Nesters

“We are achieving a four percent savings on our nest efficiency with less programming effort,” Araújo said, “which quickly amounts to a considerable sum.”

Part of that savings is due to the software’s ability to determine commonline cutting that places compatible parts directly next to each other rather than leaving a skeleton behind.

Using Jetcam software, Embraer produced dynamic nests with better flexibility than static nests due to revision control. The company has some big parts that are cut three or four times a week. These nests are longer than 100 meters with 300 different plies. For better optimization, Embraer lets the nest run overnight or the weekend and saves the results for later use. Each time it cuts the part, the engineers generate a new NC file and send it to the machine.

Getting Static

An advantage is that in static nesting and revision control, if the revision is old, Jetcam notifies the engineer when the file is opened, so the engineer won’t use it. Using static, and not dynamic nests, in these cases helps Embraer save material.

FFHPN can be configured to run for a user-defined period, so the most efficient nest can be generated within the amount of time available.

Embraer uses mosaic nesting on its routers, which shaves an hour a day from programming times. This lets “nests within nests” to be dragged and dropped onto the sheet as if they are a single component. The company uses it when there are many orders from different materials with few parts on each order.

The advantage with only one machine setup is it can produce many different small orders. Existing nests can be dragged and dropped into desired locations in exactly the same method as single components, using the bump-nesting facility.

Ongoing support and development is a concern for a company embarking on a large software implementation. Embraer drew up a detailed specification for the system.

Embraer is compiling full performance data on the routers, but the savings achieved within the composite manufacturing cells paid for the Jetcam investment in less than a year. Jetcam International

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