"Go-Between," Feature Article, May 2005

go-between

Shop floor software taps into CAD systems to get vital manufacturing information.

by Jean Thilmany, Associate Editor

manufacturing and mechanical engineers find themselves linked by more than just the words in their job titles. Although they might inhabit different parts of the plant or work at separate companies, the engineers have always worked together to turn a design into a part. Now, software that makes it easier to bridge the gap between design and manufacturing has stepped up that cooperation.

Computer-aided design systems have long been linked with the computer-aided manufacturing software that directs manufacturing equipment. CAM software takes CAD data to the shop floor by essentially telling shop-floor machines how to make a part.

CAM applications are now finding a host of new uses—for instance, to program a laser-projection system that helps operators lay out composite materials.

Manufacturers turn to coordinate measuring machines to inspect against CAD or for reverse engineering.

Beyond CAM, manufacturers are finding new uses for software that converts CAD into pertinent manufacturing information.

In this day of complex engineered parts, many companies now inspect parts against CAD specifications, rather than against blueprints. For this, they rely on inspection software that brings CAD data directly to the manufactured part. Some suppliers now reverse engineer customer parts with help from hardware and software applications that convert manufacturing measurements into CAD data.

follow the laser beam

A recently released software application that moves numbers from CAD straight to a manufacturing floor laser-projection system cut production time at an aircraft composite-part supplier by 30 percent. Lee Smith, engineering systems manager at the company, Northwest Composites Inc. in Marysville, Wash., said he expects that number to rise.

Picture an aircraft panel. Nearly any panel will do. The composite part is made up of layer upon layer of resin-soaked fabric.

"It's like layers of cloth impregnated with resin, stacked together to make up a part thickness, then cured in an
autoclave," Smith said. "The plies get stuck together when heated. The heat cures out the part."

As a manager, Smith is always on the lookout for technology that helps his operators layer the plies, which is an exacting job. Each ply must be set down just so. He recently brought in CAM software for a unique use. The application essentially translates an OEM-supplied CAD file into ply-layout information vital to floor operators. So far, it has cut layout time by around one-third.

Here's how it works. First, engineers at Smith's company import a supplier's CAD file to the software, called LaserEdge Planner. They're now using the software on its first project to help build doors for a military aircraft.

Programmers get exact ply information from that imported CAD file. They see the number of plies needed for the part and then determine exactly how each ply must be laid on the mandrel, the tool on which the plies are layered before they're sent to the autoclave.

Each ply has to be oriented very specifically and no two plies are necessarily placed exactly the same, Smith said. The company's laser, fed by information from the planning software, casts a ply outline to the mandrel. Each outline is specific to each ply and is based on planning-software numbers. The operator chooses the correct ply and places it exactly as the laser specifies.

end of art tools

Previously, engineers spent about three days creating a miscellaneous indexing tool unique to each job, Smith said. The fiberglass tool was about the same size and shape as the mandrel on which operators lay the plies. Engineers drew lines on the tool to represent each ply an operator would be setting down. It looked rather like an art template, Smith said.

"The operator would heave it up on the mandrel, mark the ply location, take it back off, lay out the ply, then heave it up there again," Smith said.

Doing away with that tool by bringing in software to help turn CAD numbers into a laser image made for the 30 percent cut in production time, he added. As employees become more familiar with the software, which has been in place only a few months now, that percentage should increase, he said. Northwest Composites brought in the software, from Virtek Vision International Inc. of Waterloo, Ontario.

Part inspection against CAD rather than 2-D data is more common when many industries, especially automotive, have smooth-flowing surfaces.

Production for the military-aircraft doors is the first project on which Northwest Composites put to work the CAD-to-laser software. The company bought the laser, also from Virtek, about a year ago and had been looking for ways to step up its efficiency.

Before coupling the laser with its planning software, engineers transcribed the CAD file on their own to determine individual ply layouts, then made up the indexing tool or programmed the laser. Now the planning application automates that laser-programming step.

"With the software, we go from model right to laser," Smith said. "The laser gets its information from CAD.

"You're not physically digitizing a CAD part," he added. "It lets you go right off a 3-D CAD model. That's the model you want to build to. You don't need to do anything to it."
The system can read many CAD systems.

automatic inspector

Inspection applications take CAD data out to the shop floor to check part specifications against the finished product. They might not spell the doom of Inspector Nine at the end of the assembly line, but those software tools prove invaluable to check manufactured parts against the original CAD design.

Most original equipment manufacturers now ask their suppliers to inspect parts against the CAD data they've supplied rather than against 2-D blueprints, said Brian Griffiths, a business development manager at Delcam, based in Birmingham, England. The company makes CAD and CAD inspection software, among other products.

The company's PowerInspect product, like Smith's laser software, reads CAD data directly into a manufacturing application. In this case, the CAD info goes directly into an inspection or measurement device rather than into a laser.

Inspecting against an engineer's original CAD data saves time and can improve accuracy from the get-go, Griffiths said.

Manufacturers can use a measuring device to check the dimensions of parts against the nominal CAD data. If the instrument houses the inspection software to translate CAD information, the system can provide instantaneous readings.

"If you had a 2-D drawing, a guy would look at the blueprint and see the dimensions specified on that, and then measure the part to see if they align," Griffiths said. "But with CAD-based inspection, you measure a feature with a measurement device. The CAD nominal is already in there and it'll tell you the deviation from the nominal.

"Another big advantage of CAD inspection is it's a lot easier," he added. "In the old days, you'd be looking at blueprints and you'd have to keep checking the release dates of the blueprints to make sure you're looking at the most recent ones. Then, you'd have to manually key all the measurement numbers into whatever software you were going to use with the measuring device."

Software applications like his company's cut inspection time by as much as a factor of 10, he said.

One of the main reasons that inspection against CAD data has become more common is the increasing complexity of components in practically all industries, Griffiths said. Automotive interiors today mainly feature smooth-flowing surfaces instead of the comparatively boxy shapes of a few years ago. It's difficult to describe these complex surfaces unambiguously in 2-D drawings. Clearly, any ambiguity in the drawing undermines the reliability of the inspection process, he said.

Stefan Schneider of Modellbau Hirt cites that reason and others for his company's move to CAD inspection software.

Schneider heads the CAD and computer-aided manufacturing division at Modellbau Hirt of Kšnigswinter, Germany. The company makes models for foundries and other automotive suppliers.

The modelmaking company recently added inspection software from Delcam. Engineers are using the software to move part data back into the CAD system.

Engineers needed that new application because many companies supply plastic or foam models of parts they'd like created. Modellbau Hirt needed to get CAD data from the 3-D models in order to make the parts. And those supplied shapes can't be measured by hand, Schneider said.

"In model making, you often have to work with free- form surfaces, which can't be measured by geometric methods at all," he said.

Engineers recently tied the measuring system and inspection software to generate CAD data for a toy trailer. "The starting point was a model made of foamed plastic," Schneider said.

To get the construction geometry, he measured key points on the model with the measuring system. The inspection software translated those numbers back into the CAD system.

The company uses the PowerInspect software coupled with a PowerShape CAD system, both from Delcam. Its measuring machine is from Zett Mess of Sankt Augustin, Germany.

starting with a shape

Modellbau Hirt used its inspection and measurement software to reverse-engineer a part back into the CAD system. That technique is finding a following.

A pattern-making company in Toronto, Formglas, uses a portable coordinate measuring machine arm to reverse-engineer metal parts, said Joshua Waterman, a company supervisor.

Formglas traditionally makes molds for a variety of building and recreational products that include architectural columns and casino gaming tables and displays. Customers want to reproduce original products but make them from composite with gypsum filler. To do that, they need the mold supplied by Formglas.

A big part of the company's business naturally came from architects and designers who needed a unique shape formed, Waterman said. Recently, Formglas engineers branched into another line of work. They still make architectural and design molds, but they're also taking on customers in the aviation, trucking, and marine industries that want to convert their metal parts into molded parts.

Engineers at Formglas capture the metal part's free-form surfaces with a portable coordinate measuring arm that digitizes parts within an eight-foot spherical reach. For this, they use the FaroArm from Faro Technologies Inc. of Lake Mary, Fla.

Part information sent to a portable measuring arm's CAM software package can be sent directly into any number of CAD applications to create a digitized part.

For big jobs, engineers turn to a portable measuring arm, called a Tracker, from the same vendor that projects a laser beam to a movable reflector mounted on the part to be measured and then back to the arm.

"Our customers may not always have drawings of the objects from the OEM who made the item," Waterman said. "When they want to modify the design or convert the object from metal to a molded composite, we digitize the surface so we have an electronic image of it."

The data that define the part are fed into the digitizer's software package, called CAM2 Measure, from Faro. Information from that package can go directly into any number of CAD applications, although Formglas engineers usually work in Catia from Dassault Systémes of Paris.

Engineers at Formglas then work with customers to modify the CAD design. It often must be slightly altered from the original to account for the requirements of the molding.

The company has digitized everything from wheel parts for light aircraft to entire airplane wings.

Recently, engineers reverse-engineered an engine shroud for a light plane. The part measured just over four feet and included some complex curves critical to the craft's aerodynamic performance, Waterman said. The shroud had to be recreated at exactly the same dimensions as the original part, he said.

The Formglas operator dragged the measuring arm over the cover to build a 3-D point cloud of the surface. When that surface was converted into CAD data, engineers completed the job by checking things like rib placement and reinforcements, and adjusting the design to make sure that the cover could perform aerodynamically and that it could be molded.

Applications like these that are taking CAD data out to manufacturing, for one purpose or another, have been finding their home over the last several years. Whether for programming a laser, reverse-engineering a part, or something else entirely, these applications bring the intentions of the design engineer closer to the manufacturer.

Lee Smith of Northwest Composites summed up his company's incentive for bringing in the technology: "This new system cuts the number of tools we need, and it increases accuracy." It also may save someone from having to reinvent the wheel, or any other part.