Machine Design

Software generates top-notch surfaces and more

Icem Surf software is well suited to designing Class-A surfaces, those that consumers see and feel on products, and could influence buying decisions.

The surface model was designed in Icem Surf by engineers at Eifel Mold. The porcupine display on the edges shows a curvature graph of section information. These can be used to find minimum or maximum curvatures values, and identify flat spots, sharp edge, and poor matching across surface boundaries.

The same part in zebra stripes depicts highlight flows across the part. This type of surface evaluation provides instant visual feedback on surface quality.

The Lamborghini Gallardo is rendered in Icem Surf. Visualizations such as this are useful in design reviews and approvals during development projects.

The software has many ways to model advanced surfaces, analyze them, and realistically render them for design reviews.

For instance, the software easily imports and manipulates data in the form of millions of individual points from nontactile measuring devices and as faceted data generated by any of several 3D scanning devices. Point clouds and faceted data often come from physical items, such as hand-shaped clay models. These free-form contours are not easily generated in CAD. To accommodate this modeling method, a "Quick Surfacing" feature lets users create surface models from scanned data through a user-defined patch structure.

Surface models from scanned data are also suitable for simulations, such as computational fluid dynamics (to see how air flows over a car body), and to start developing molds. Surfaces can be modeled directly, without first constructing or modifying edge curves. Design changes are quick and easy in this so-called direct-modeling method. Adjustments are made with functions for smoothing, approximating, control-point modification, and modifying curves.

Users make standard surfaces by revolving or extruding a line. The software also generates canal surfaces, offset surfaces,and profile surfaces. Constant and variable-radius-fillet surfaces can have tangency and curvature continuity to adjacent surfaces.

Associativity, dynamic surfaces, and curve diagnosis operate in parallel with surface construction and building features. Other real-time analyses include examining the relationship between adjacent surfaces such as intersecting curves of two surfaces, reflection lines, forming edges, bends, turning lines, and sections. Several topology analyses examine the transfer of tolerances between adjacent surfaces.

Advanced modeling — broken into unified and reality modeling — are particularly useful. Unified modeling lets designers dynamically modify surface data through a referencegeometry mesh while the model is "projected" onto reference data. This allows the user to map existing features or geometry to new underlying surfaces, and it works whether the referenced surface model data was generated in Icem Surf or imported from another CAD system.

Reality modeling, the second item, is particularly useful-in design reviews. It lets users make modifications, dynamic-form changes, and conduct surface diagnoses while maintaining photorealistic versions of models with shadows and reflections.

Additional tools analyze models for level, gaps, and flatness. Leveling starts by selecting a part and nearby reference geometry. The software extrapolates reference surfaces in tangent directions and compares them with object surfaces. Deviations are shown by a vector mesh or color map with minimum and maximum deviation in numeric values.

Gap analysis requires selecting two or more adjacent surfaces. The software measures the distance between adjacent edges and identifies the out-of-tolerance gaps both graphically and numerically. This quickly identifies areas that require additional attention by the designer and greatly reduces the amount of time spent searching for minute gaps and mismatches between surfaces. Flatness analysis and crowning (or vaulting) are useful for developing molds. Flatness shows curvature and the extent of flat areas. The result is a graduated color-shaded image. This is useful when used with crowning, which lets tooling engineers compensate for the spring-back of sheet metal after it is stamped.

Another moldmaking aid is the graphical representation of split or parting lines. The vector that represents direction of draw can be dynamically varied. A line is shown on the math model indicating the parting line and is dynamically updated as the direction of draw vector is changed.

The software was originally developed for Unix workstations, but is now more commonly found on Windows-based PCs. It doesn't have the Windows look and feel, but that's coming later this year. Still, icons in task bars and drop-down menus in the current version are clear and easy to understand. Training takes about five days for the base software (Icem Surf Professional) and can be conducted at the user's site. Advanced training is an additional five days. Optional software modules cover advanced surface analysis, global/unified modeling, and real-time rendering. Each module requires one to four days of training. Technical documentation comes in hard copy and electronically. It's extensive, well laid out, and easy to follow.

Ongoing support after formal training is just a phone call away. The problems we encounter are usually resolved by phone, and when necessary, by a personal visit from one of the developer's technical experts. Furthermore, an active Icem User Group allows exchanging views and experiences. It also gives users a forum for asking for additional features from the developer. The $27,000 program comes from Icem Inc., 300 Galleria Officecenter Dr., Suite 305, Southfield, MI 48034, (248) 351-0917, — Richard Hecker

Richard Hecker is president of Eifel Mold & Engineering Inc., a productdevelopment and tooling center in Fraser, Mich.

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