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Rx = CAx specificRx = CAx specific

DN Staff

March 26, 2001

8 Min Read
Rx = CAx specific

General CAD programs are the core of design, but with the continued pressure on suppliers to produce more reliable products faster, specialized applications that incorporate material behaviors and parameters play a key role. From stamping and forging to injected plastic, niche products help small companies remain agile, and give the flexibility needed to suppliers.

"Standard CAD tools might be able to model sheet metal, but the behavior of metal when folded is not included in the program," notes Jean Danrez, director of Hermes Metal, based in Auxerre, France. "In the last few years, we've seen a number of applications or add-ons that include these characteristics. The specialized sheet metal applications on the market today have integrated much of the 'savoir-faire' we need to correctly manipulate this material."

Design is also now connected to manufacturability. The ability to foresee and correct eventual problems during metal stamping or injection molding can save hundreds of hours of trial and error at the manufacturing stage. This has become particularly true for automobile suppliers that have seen OEMs increasingly keeping design in-house, and looking to suppliers for process management.

"The OEMs we supply to are now asking us to improve the product and the process for all parts that we have to produce," says Jiane Lu, analysis and development manager at Oxford Automotive (Elancourt, France). "This makes the use of a stamping simulation tool essential."

Smart investing. However, taking on a niche application needs to be well considered. Many smaller companies find that it is more efficient to purchase studies from either material suppliers or engineering firms. For instance, Tectro (Saarburg, Germany), a manufacturer that specializes in plastics, purchased Moldflow studies for critical applications to supplement its in-house expertise for a number of years before investing in the application.

Once the decision is made to purchase, the specific company situation will help to define the best choice. Ease-of-use is often cited as a prime criterion for smaller companies that don't have as many highly trained engineers available. The ability of the application to reliably interface with the company's existing applications is also crucial to the choice.

"We regularly use both Catia (Dassault) and Pro/Engineer (PTC), so a stand-alone Moldflow program is preferable," states Tectro Development Manager Uwe Becker. "We would only consider a Moldflow application inside Catia if we had sufficient workload in that CAD application. It's important to consider that while we would certainly get some benefits from having Moldflow within Catia, it would also mean having someone trained and dedicated to using Moldflow within the complicated Catia v4 interface."

Other considerations include downstream use of the file. If it is analysis results to be delivered to an OEM, very often it must be in the OEM's "native" format, (i.e. using the same application as the OEM). If the file is for the supplier's subcontractor, even simpler formats may be needed.

Hermes Metal, for example, manufactures some of its parts and outsources others. For the parts produced in-house, the manufacturing programmers use the same specialized CAD tool that the designers have, to unfold the part and then transfer it to its niche sheet metal CAM application. When a part is outsourced, however, they translate the file into DXF format. "In general, our subcontractors have simpler programs, which often come with the machine tool itself," Danrez explains. "The overwhelming majority of the time, this means they need DXF format."

Analyze before you buy. "Small companies should really perform a make-or-buy study before any purchase," advises Tectro's Becker. "These software programs can be expensive, so companies should be sure that they have enough work to off-set the cost of the purchase."

Training and evaluation are also essential. With one or two new releases per year, a company really needs to foresee having someone trained and dedicated to the system's use in order to be effective. "We insist on an evaluation period of several months even after the training period," adds Danrez. "There can be quite a difference between a great demonstration, and finding yourself 'trained' and seated in front of the screen while the boss is demanding finished parts!"

For a closer look at how the above companies apply niche applications, read this story's sidebar entitled "Specialized applications for specialized business."


&HEADLINE>Specialized applications for specialized business&/HEADLINE>

CatalCAD: specialized CAD

French company Hermes Metal produces metal shelves for large supermarket chains. With a product that uses extensive amounts of sheet metal, the company opted for TopBend from CatalCAD six years ago, which is dedicated to sheet metal, and CatalPA, a sheet metal CAM application.

"We chose specialized applications because we really needed a product that could integrate the particularities of sheet metal," says Director Jean Danrez, adding, "We don't have the same problems as a company that produces solid parts. Sheet metal is exceptionally thin, and therefore requires real expertise to manipulate it. It spreads a bit when folded, for example. There are a number of specific characteristics that require very specialized functions in the modeling program."

However, file transfers are not always the easiest. The graphic motors in the CAD and the CAM applications are not the same, requiring some healing of the models. For internal use, Hermes Metal partnered with Delphi to develop an application based on Oracle that allows other personnel to access the plans in jpg format.

"The best option would be a niche application that can easily communicate with all the applications throughout the company," notes Danrez. "But I'm a realist. We know how to handle the translation difficulties of our current applications, so I'd rather stay with lighter applications that our personnel know how to use. It would be unreasonable to take on a complicated application that is both more expensive and not necessarily adapted to our needs."

Moldflow: CAD and tooling

Tectro GmbH has been making plastic parts and complete assemblies since 1937. As one of the rare companies that has been dedicated to plastics since its inception, Tectro has three core businesses: automotive, supplying plastic parts and complete steering assemblies; dishwasher parts, as the exclusive supplier in Europe to Whirlpool; and automation, supplying valves for braking systems. The company offers a complete range of services in-house, including conception, tooling, prototyping, die-casting, and reactive injection molding, as well as the finished part.

The company uses Catia to design parts that have large surfaces, and Pro/E for more solid-related parts. "In general, we can handle any file transfers necessary to and from one or the other of these CAD applications," explains Uwe Becker, Tectro development manager. The company uses Moldflow Plastics Advisor during the part design to test manufacturing feasibility. When designing the mold, and defining all the parameters for the injection process, Tectro uses Moldflow Plastics Insight (MPI). "MPI can evaluate the runner and cooling systems during the mold design, and we use it to perform studies on warpage and shrinkage rates," Becker points out.

The company is currently evaluating Moldflow's MPx, which allows Moldflow data from an analysis to be input directly to the injection mold machines. "The ability to have 3D data throughput from the design to the injection mold machines would give us an enormous advantage," says Becker. "Not only will we be able to have a much faster start-up time, but the program should be able to supervise the process so we can make adjustments on the fly.

"One of the big advantages to Moldflow," he adds, "is that it gives a very complete materials database. Most of the common materials are already there, and additional materials can be added as needed. The fact that the application is well-known is also reassuring to our customers."

Optris: stamping, and even meshing

Oxford Automotive is an international automotive supplier, with 41 offices in North and South America and Europe. While the company's Troy, Michigan headquarters uses PAM-STAMP (ESI) for its stamping simulations, the French subsidiary chose to use a different application, Optris (recently purchased by ESI).

"We use Optris both for its ease-of-use and for its good correlation with physical tests," says Development Manager Jiane Lu. "The GUI (Graphic User Interface) is particularly friendly, and there is a full range of interfaces for other software. Optris also runs on a PC, which is a big cost advantage. We use it for stamping simulation, validation of the nonlinear behavior of some products, and even for crash simulation."

When testing thin metal parts, even the best-known crash software does not have the correct criteria for failure detection. Since OAFrance specializes in stamping, folding, and assembly of sheet metal, they use Optris to compare the Forming Limited Diagram and the Forming Limit Curve of the material to efficiently detect any failures that would occur during a crash.

"We use many, many applications, and we're always looking for better productivity," explains Lu. "Sometimes that will mean using an application for something that was not even designed as its primary function. My main concern is to be sure that the benefits outweigh the costs, so productivity is the key. Ease-of-use is therefore one of the most important criteria, so that even our personnel that do not have PhDs in engineering can still use the program correctly."

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