CAD/CAM Add-In Automates 80 Percent Of NC Programming Tasks

Faget (Steenwijk, The Netherlands) produces a range of products for manufacturers of electrical power transmission and distribution equipment. The company makes measuring instruments in analog and digital versions that are used in control panels for the power industry. It also manufactures toroidal core transformers, which can be used, for example, as flush-mounted measuring and protection transformers in high-voltage switch installations.

The company designs and builds the molds used to manufacture most of its products. In the past, the company's designers used a 2D CAD software package to create the mold design, and they wrote a series of macros in a 2D CAM system that performed much of the process of converting the design to a CNC program. One problem with this approach was that working in 2D placed major limitations on the geometry of the designs. Another problem the company encountered was that the macro language of the 2D CNC system was somewhat inflexible and difficult to maintain. Each element of the geometry had to be placed on the right layer of the drawing, or the CNC program would be generated incorrectly. If the designer duplicated geometry in the design—such as placed lines on top of each other—then the program would instruct the machine tool to re-machine the same geometry several times.

Dick De Rooij, chief of engineering at Faget, says the company that provided Faget's CAD software offered an upgraded version, which was capable of producing 3D designs. Faget's CAM software, however, was incapable of programming 3D designs. So Mr. De Rooij started examining various CAD modeling and CAM programming packages.

Then a local value added reseller (VAR), Somatech Applicaties (Veenendaal, The Netherlands), suggested that the company try the Esprit CAM system from DP Technology (Camarillo, California) and UGS' (Plano, Texas) Solid Edge CAD system, in conjunction with its ConcurrentCAM add-in, which enables the CAD operator to specify manufacturing instructions during the design process.

ConcurrentCAM has been made possible by DP Technology's support of the Visual Basic development environment through Esprit's application programming interface (API). The API supports any Windows programming language, allowing developers to build their macros and add-in programs in their language of choice. All of the menus and toolbars are accessible from within an add-in program, so it is possible to adapt the user interface to suit the specific needs of a particular application or business. For example, a network developer has the option of building a macro or add-in so that it appears as an integral part of the program.

Faget's engineers begin by designing the part in Solid Edge, defining the various features of the mold, such as pockets, bosses and holes. Having been trained in machine tool operation and capabilities, the designers generate the CNC program that is used to produce the part. They begin by selecting a feature, such as a hole, and call up the ConcurrentCAM add-in. The first button allows the engineers to add written documentation about the feature. This can be used to provide useful information to another person who may need to modify the program at a later date. The designers then use the second button to add further detailed information needed for machining, such as whether it's a blind- or through-hole, into the part design to be used when the tool path is built.

Clicking the third button populates a list in Esprit of cutting tools that are available for machining the feature. In the case of a hole, for example, the engineer selects a particular drill. Machining feeds and speeds have already been associated with each tool through the program's database. When the engineer has processed all of the features on the part, he or she presses the final button, and the program generates the tool path and G code required to machine the part. The G code can then be simulated and verified inside the program. Sometimes, the designer may realize that the final geometry does not exactly match what he or she had intended to produce. In such a case, the designer can return to Solid Edge and modify the design.

"This new approach means that we rarely have to manually interface with the CAM system," explains Mr. De Rooij. "Esprit searches Solid Edge to determine the position, size, shape and depth of each feature. Subsequently, it automatically creates the G code to produce them. The engineer must only enter certain information that the add-in is unable to determine, such as nonstandard tooling needed for a specific cut."

When the engineer designs the part, he/she can also consider how it should be machined. The result is that the company has automated 80 percent of the CNC programming process. This is because complex molds can be produced in less time than with the programming methods they were previously using.

Mr. De Rooij also reports that working in 3D improves product design. "The design can be viewed and understood by other people, such as the customer or salesperson, who often have suggestions as to how to improve it," he continues. "Rotating the design and viewing it from different angles allows everyone to understand how it works. Our engineers can visualize the different possibilities, and they can often identify problems or suggest improvements that would otherwise not be noticed until the prototype was built.

"Additionally, once the design is finalized, the machinists can view the 3D geometry to attain a better understanding of how to build it," concludes Mr. De Rooij. "There are plans to implement these same methods to create programs for wire EDM machines. The bottom line is that the add-in, in conjunction with Esprit and Solid Edge, has enabled us to produce better designs while reducing the time required to move them into production."