The ultimate Step

The ultimate Step

At last, manufacturing interconnects with design and engineering.

At last, manufacturing interconnects with design and engineering.

With Step-NC, it is now possible to exchange information consistently and smoothly between CAD, CAM, and NC programming.

The Step-NC test environment at DaimlerChrysler involves the machining of a powertrain part on a Hermle 5-axis machine with a Siemens Step-NC user interface. CATIA V5 provides the 3D design and OpenMind the 2.5D programming.

Step Tools Inc. successfully demonstrated its Model Driven Intelligent Control of Manufacturing program. Referred to as the Super Model, it combines data from multiple Step application protocols while providing an easy-to-program interface using the new Step implementation technologies.

Shown is a working step of the DaimlerChrysler Step-NC testing. It is possible to change or add to the sequence of working steps. A window displays the steps taken out of sequence, but they remain inside the information set of the physical file so they aren't lost.

Design engineers have been sharing data for years with Step (Standard for Product Data Exchange), which became an ISO standard in 1994. Now, that same data has made its way to the shop floor and is running machine tools. Basically, the standard is the smooth and seamless exchange of part information between CAD, CAM, and NC programming. While the standard is now in use at companies worldwide, it typically encompasses just the sharing of CAD geometry. But thanks to two recent initiatives, one in Europe and one in the U.S., the chain is complete, and the Step standard is spreading to NC programming in the form of Step-NC. It supports the feature-based link of the CAD world within the CAM/NC world.

Currently, a Step-NC prototype is being tested at the DaimlerChrysler plant in Stuttgart, Germany, and involves the cooperation of a number of industrial companies, information-technology vendors, and universities. DaimlerChrysler is providing the machine and performing user tests, Siemens is responsible for the controller, and software vendors (Dassault Systemes and OpenMind) handle the CAD/CAM integration.

The focus of the testing is prismatic milling and drilling applications. After the first exchange of data for 2.5D milling, the test will expand to cover 3D milling. The NC machine tool, a 5-axis Hermle, is equipped with a Siemens 840D controller, which is modified with a Step-NC interpreter and the appropriate user interface.

In test scenarios, generated code from Dassault and Open-Mind systems feeds into the Siemens control. For this, a Step-NC output filter expands the Catia V5 and OpenMind/Vamos CAM applications. The Step-NC control understands the new data format and displays the necessary working steps on the operator's panel.

If necessary, all the information belonging to the working step can be displayed and modified. This includes deleting or generating working steps. Operators can also edit the sequence of working steps to optimize machine movements.

When a machine's supplied tooling is not defined, the type of operation can also be changed — for example, enlarging a hole by milling instead of drilling. These modified data sets then directly generate a new physical file, which is archived.

After this, operators simulate the working steps and make any last corrections, such as adding tools to the toolchanger. Once the program is approved, processing the workpiece starts, and during production, the NC operates like any other standard control.

The machine's screen displays working steps with all related information. On the left side there is a collection of the working steps, which was generated from the content of the ISO 14649-file. Selecting a working step opens a window on the right side and displays the information about the feature, its geometry, the needed manufacturing technology, and necessary tool information. And compound features can be located at several positions.

Programming information can be exchanged and edited in all the views based on the feature concept. For instance, when programming a drill, the user employs the CAD/CAM environment Catia to program the NC drilling cycle based on the Step-NC and feature approach. The new Siemens user interface immediately under-stands the Step-NC feature definition, maintaining full associativity. Editing in G and M codes is no longer required.

Step in the U.S.
On November 30, 2000, Step Tools Inc. of Troy, N.Y., demonstrated its Model Driven Intelligent Control of Manufacturing, otherwise known as the Super Model project, during its third Industrial Review Board (IRB) meeting. This event took place at the Benet Laboratories of Watervliet Arsenal.

The demonstration used Cadkey for functional design, FB Mach for manufacturing design, and EasyCAM for process design. Cadkey is a mechanical design CAD that can read and heal the geometry of a wide range of other CAD systems; FB Mach is an advanced feature-based manufacturing system developed by Honeywell for the Department of Energy; and EasyCAM is a CAM system that was integrated into a PC-based Bridgeport controller. With EasyCAM, toolpaths were dynamically generated at the machine's controller using Step-NC data.

The project is using Step (Part 21) to communicate between the database and the CAD/CAM systems in addition to an XML client-server architecture to communicate between the database and the machine tool controller. The implementation of the database and interface combines data from multiple Step application protocols (AP-203, AP-224, AP-213, and ISO 14649) while providing the client application (the intelligent controller) with an easier-to-program interface using the new Step implementation technologies Express-X (Part 14) and XML (Part 28). In a second Step milestone, General Dynamics Land Systems hosted a demonstration of the Super Model. It replaced EasyCAM with Virtual Gibbs for process design and integrated it with an advanced Open Modular Architecture Controller (OMAC) developed by Lawrence Livermore Laboratories and General Motors.

The Super Model project actually started in 1999 when Step Tools received a $2 million Advanced Technology Program (ATP) award issued by the National Institute of Standards and Technology (NIST), an agency of the U.S. Commerce Department's Technology Administration. Specifically, the award funds the development of software and databases for an integrated design-to-manufacturing system that allows numerically controlled (CNC) machine tools to be controlled by product design data.

The three-year project's goal is to build a database that contains all the information required to tool a part — in other words, a super model. This database will be defined by Step and Step-NC standards. The project is challenging and special because of the range of information that must be integrated into the database. A principle benefit of the project will be easy-to-use libraries that make it reasonable for downstream manufacturing tools to annotate and extend information defined by upstream design tools.

The target for the first year of the ATP project is to build a Step and Step-NC database containing three kinds of manufacturing features and use the database to drive a machine tool controller. The goal for the second year is to build a database containing all the features required for NC milling. The plan for the third year is to build and manufacture a database for another machining process, such as turning, EDM, or grinding, to show the flexibility of the Super Model database.

After receiving the ATP award, Step Tools began forming the IRB, which consists of Fortune 500 companies, software developers of both CAD and CAM products, machine tool manufacturers, and jobshops, along with industry experts and consultants to advise and participate in the Super Model project. The IRB meets twice a year to review the project progress and interact with the Step Tools team.

The review board is made up of: Alibre Inc., Benet Laboratories, Cadkey Corp., Cambridge Valley Machining, CamSoft Corp., Caterpillar, Rensselaer Polytechnic Institute, CIM-plus, CNC Software, DaimlerChrysler, Dutchess Precision Industries, Electro-Mechanical Integrators, Fala Technologies, Ford Motor Co., General Dynamics Land Systems, GE Corporate R&D, GE Fanuc Automation,

General Motors Powertrain, Gibbs and Associates, Honeywell FM&T, Hurco Companies, IBM Corp., IBM Software, NASA Jet Propulsion Laboratory, Lawrence Livermore National Laboratory, Liberty Consulting, Lockheed Martin Tactical Aircraft Systems, LoDolce Machine Co., Monarch Machine Tool, NASA Goddard Space Flight Center, National Center for Manufacturing Sciences (NCMS), National Institute of Standards and Technology (NIST), Otto-Tech Machine Co., RMC and Associates, Tech Industries, Boeing, Design Edge, Unigraphics Solutions, and the U.S. Army.

Dr. Martin Hardwick, president and CEO of Step Tools and recently appointed leader of the Step Manufacturing team, believes "Step-NC will change the face of manufacturing as we know it today." And he plans to showcase the tangible benefits of this new technology, such as 50% faster machining, 75% more efficient sending of RFQs, and 35% quicker conversion of CAD-to-part programs at the company's North American Center for Step-NC Technology.

Opening in June of 2001 and located in Troy, N.Y., the center will serve as an educational focal point for industry and the general public interested in next-generation manufacturing. To replicate real-world scenarios, the center will house a demonstration area that includes a CNC machine tool, CAD/ CAM systems, and a high-speed Internet connection. A library of materials covering Step and Step-NC will be available, and visitors can see the latest developments in Step Tools' Super Model project.

The European players

The European Step-NC project (ESPRIT EP 29708) supports the R&D as well as the deployment of the technology. Within this consortium there are more that 20 partners from both industry and academia that collaborate to develop prototypes. For the first prototype, representatives of Siemens, DaimlerChrysler, Volvo, and Open-Mind were the major drivers. They were supported by the technical university of Aachen (RWTH --WZL) and university of Stuttgart (ISW). Other partners include Osai, CADCAMation, AMT, CECIMO, Agie, Charmilles, CMS, Starrag, EIG i-tech, EPFL, ISW-Stuttgart, WZL-Aachen, Derendinger, Franci, Progetti, and Wyss.

Dr. Weyrich is employed by DaimlerChrysler AG. Additional information for this article was provided by Dr. Martin Hardwick of Step Tools Inc.

TAGS: Features
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