Today's CAD innovations set you free—with a history
By Staff -- Manufacturing Business Technology, 3/1/2007 12:00:00 AM
History-free CAD tools—sometimes called dynamic-modeling or direct-modeling tools—are slowly but surely replacing oft-used history-based or parametric CAD applications. History-free systems simplify the design process using the same powerful 3D features of history-based tool sets.
Benchmarks from Boston-based Aberdeen Group indicate nearly three-quarters of manufacturers intend to use 3D modeling, primarily to escalate time-to-market.
Differences between the two approaches can be difficult for nonexperts to grasp, but mostly boil down to how data is captured and managed within models and shared between applications.
For instance, in history-based models, solid faces are represented as the total—or history—of all the sketches, extrusions, protrusions, and modifications used to create them. Relationships between these factors are embedded in the model, acting as a “recipe” for recreating or modifying it.
In history-free models, a face is comprised of the geometric characteristics themselves.
So when it comes time to change a model—or even one part of it—the historical approach requires changes to all the “ingredients” in the recipe. History-free tools allow designers to make targeted changes directly, without understanding all the underlying constraints or waiting for the whole model to rebuild.
Chad Jackson, research director at Aberdeen, says history-free tools work well when designs are frequently passed between users, or undergo dramatic change. Feature-based modeling offers efficiencies within families of products, particularly those that share common design criteria and rules that automate configuration.
The decision on what to use may depend on how much data sharing is necessary. “Geometry can move between CAD systems, but history trees typically can't,” points out Todd Black, communications manager for product life-cycle management (PLM) vendor CoCreate, which offers history-free systems.
Privately held CoCreate is near unique among PLM/CAD vendors in that it's a midsize company with about $75 million in revenue. Its specialty is in high-tech and machinery—two sectors with “high-tempo development and refresh cycles,” says Black.
In particular, CoCreate solutions are in use by many printer manufacturers, including Seiko Epson, which chose CoCreate OneSpace Modeling and Model Manager to replace a history-based system that proved too restrictive for engineers trying to reduce the size of printers.
Other collaboration vendors with solutions that lead to design process flex include Kubotek USA with its KeyCreator geometry-based tool. KeyCreator is in use by Ontario-based plastic injection molder Bernard Mould to frequently import models or enable needed flexibility late in the design process.
Kubotek recently launched Face Logic, a solution that enables quick editing of solids without breaking them down into separate surface entities, and other dimension-driven editing features more often associated with parametric systems.
Solid modeling vendor IronCAD offers hybrid capabilities like feature trees, which give designers access to histories, as well as the ability to directly modify underlying geometries regardless of their history.
