Nowadays, everyone is talking about model-based definition (MBD) and model-based enterprise (MBE). The thrust of this concept is to associate the information that would normally be contained in the drawings with the 3D model as PMI so that it can be used for quality assurance, manufacturing and other tasks, thus largely eliminating the need to create drawings at all. Continental is currently gaining initial experience with implementing the concept in various pilot projects in the company’s Automotive division, explains Constantin von Bernuth, IT expert for mechanical product design at Continental.
With annual sales of 39.2 billion euros and a workforce of approximately 215,000, the Continental Corporation is one of the biggest technology companies in the world. Founded more than 140 years ago, the company develops, manufactures and markets innovative solutions for safe mobility, intelligent driving, worldwide mobility and environmentally-friendly powertrains at 430 sites in 55 countries. The corporation is headquartered in Hanover and comprises the divisions Interior, Powertrain, Chassis & Safety, Tires and ContiTech. Like many other automotive suppliers, Continental has a heterogeneous CAD environment with PTC Creo and Catia V5 as the two leading mechanical design systems.
The MBD initiative was driven by two things: On the one hand by the Testing department, which was looking for more efficient ways of controlling the CT scanners and measuring equipment, and on the other hand by the stated aim of many car manufacturers of wanting to dispense with drawings in the foreseeable future. The priority was not to reduce the outlay involved in creating drawings, but far more to exploit the time savings in the downstream processes, as von Bernuth points out: "The direct savings are actually not that large. After all, much of what used to be recorded in the drawings still has to be recorded in the 3D model." Investigations by Continental showed that it was possible to dispense with between 10 and 15 percent of the annotations because individual elements no longer had to be created in different views.
Evaluation of the PMI information
When establishing the drawing-free process, Continental based its concept on VDA Guideline 4953-2, which describes a reference process covering creation of the user data in the CAD or PLM system, generation and distribution of the 3D documents, and the use of documents in various use cases. To supplement this, DIN ISO 16792 specifies how dimensions, tolerances and other PMI are to be associated with 3D models. For example, the standard requires that the information must be selectable, i.e. not all element types, such as references, tolerances and surface quality, are allowed to be located in one (isometric) view. It is, however, possible to create additional 2D detail views in which they can be mixed.
One of the use cases for the drawing-free process that was implemented by Continental several years ago is quality control. This involves passing the PMI from the Creo models to the scanning software in order to check that the geometrical tolerances of the actual model are within specification. Any discrepancies are highlighted on a false-color model and listed in a report. It should be noted that it is not the geometries of the CAD model and the scanned model that are being compared but rather target values and actual values, which is a far more accurate comparison. "We used to have to re-enter the tolerances on the scanned model, which was a very time-consuming job," explains von Bernuth. "The automatic transfer of PMI information has significantly reduced the time needed."
Within the company, the MBD data is used not only in the Testing department, but also in Purchasing and Research & Development. The primary external recipients are the toolmakers and the suppliers that manufacture certain components for Continental. If drawings are to be dispensed with completely, it is of course necessary that all the employees at the company and in the supply chain are able to visualize the annotated 3D models. The company's own employees are able to use Creo View.