Parametric: how?

Most so called “Parametric CAD Systems” in use today have their foundation in “History Based Modelling”. This means that the parameters the user can change later are defined as the user creates the model. This approach is a fairly pervasive design technology, so we won’t go here into the advantages this technology brings to the user. Essentially, the design intelligence is built into the model and its history. However, this approach also has its problems, and we need to consider that this isn’t the only way to apply ‘parametric’ changes to a design. KeyCreator, by Kubotek – a creative Japanese manufacturing company with subsidiaries in USA, Europe, and China – has a unique parametric methodology. KeyCreator’s parametric function works directly on model geometry, without the need to access model history. You might say that it is ‘intelligent’ software that works with ‘dumb’ geometry – whether native or imported. So, while most parametric CAD systems results are history- based, KeyCreator is founded on direct geometry editing, freeing the user from limitations arising from the way the model was created. Consider this. In a History-based system, if a sheet metal bend is created manually by simply modelling the internal and external blends, the user will be unable to unbend the part, since the system will not have the data to perform the operation. In the same example, if it is created as a sheet metal bend the user will be unable to change the internal or external blends, since this will violate the bend constraints or the system will simply not associate the blends with bending. This leads to situations in traditional parametric CAD systems where some changes are impossible due to model history, especially if the design intent is not understood because the model was created by someone who may no longer be available for ‘inter-human interrogation’. The current user will then need to recreate parts of a model in order to be able to make necessary changes. In some situations, it becomes quicker to simply start from scratch and recreate the model. Another limitation for history-based systems is related to the import and export of data to/from other CAD systems. All the history data falls away as soon a model is exported via any neutral format. So the “intelligent model” suddenly becomes “dumb,” losing most of the value added from the system used to create it. In the last few years, Kubotek has focused the development of KeyCreator to solve or at least to reduce these problems that mechanical engineers face daily. To do this, KeyCreator is based on a completely different modelling paradigm. Any editing commands work on the basis of Direct Geometry Editing. Onto this foundation the Kubotek development team is continuously adding new functions and capabilities to KeyCreator. Direct Geometry Editing provides KeyCreator with the capability to edit/change geometry without the need to access any special intelligence built into the model to be changed. In KeyCreator the pure geometry is editable and provides the user with full control over design changes. KeyCreator does this by using its ‘internal intelligence’ to propose ways to the user to modify a model. KeyCreator analyses the pure geometry to categorize and display different types of features and relationship information it recognizes on an area of a model. The user may direct this process by detecting specific feature types, then selecting and applying changes to the recognized parameters on the selected features. Essentially, KeyCreator ‘mines’ the geometry data to provide the user with human-recognizable feature types – such as pockets, hole features, protrusions, ribs, blends, bends – to change, delete, relocate or copy. For example, in the foregoing sheet metal exercise, KeyCreator can recognize from the ‘dumb’ geometry both a bend and a set of blends and make changes to bend angle and fillet radii with little effort. The Kubotek development team have gone even further with this approach, and KeyCreator now introduces Direct Dimension-driven Editing. With this technology the user can help the system to understand how he wants to change the model. The KeyCreator user simply freely adds standard 3D dimensions to the model, then edits the dimensional values to effect model change. By using KeyCreator’s intelligent geometry recognition and selection in conjunction with these dimensional edits, a single dimension can drive multiple change scenarios – determined by the user and not governed or constrained by model history. So, KeyCreator proposes a change in behaviour based on the dimension selected, but the user can interact with the system to modify that behaviour to edit the model as he wishes. The dimensions may be retained for later edits, or ‘thrown away’ and recreated later if needed again. The designer has the liberty of creating new geometry without respect for a sequence of operations, knowing that anyone else who needs to make a change later can do so without having to consider any constraints or model history. Kubotek Corporation holds a vision of a new Renaissance, one where creative human beings are at the center of the design and manufacturing process, and technology works for them. KeyCreator fits into this Kubotek vision. Too often, the user must adapt himself to the technology, when the technology should serve the user. Kubotek Corporation’s conviction is that intelligence resides in the creative designer, not in the design or model. The CAD system should simply provide the tools needed to apply intelligence to the design process and drive it as the designer wants, without constraints set by someone else – or by the tools.