Today's Solid Modelers—Key to Art-to-Part Success31 Dec, 2002 By: Mark Huxley,Steven Weisberg
How close is the goal of an all-digital design process?
The CAD/CAM/CAE industrys quest to provide manufacturing customers with art-to-part capabilities-taking a design from concept through production in an entirely digital environmenthas been around for decades. Though several classes of software help make this happen, a critical foundation element is the definition of products via electronic 3D solid models instead of 2D drawings (electronic or not). Todays MCAD applications and related
software offer powerful features that can contribute to the success
of the art-to-part product development.
Previous Cadalyst articles, "Move Your Art to Part" in March 2000 and "Digital Workflow Speeds Product Design" in November 2001, demonstrate with detailed examples how the digital process offers numerous benefits over traditional methods, with only minor drawbacks. Prime benefits include higher quality products designed through better communication between the various parties and higher profit because of a faster time to market.
|Figure 1. An industrial designer, using Alias Studio, modeled and rendered this toothbrush sanitizer in about six hours. Image courtesy of Alloy Design.|
The advantages of solid modeling include interactive 3D design, accurate and better visualization, detail manipulation, diagnostic tools, design integrity, and model reuse. Users can produce prototypes far more quickly (see "RP Cuts Time to Market," May 2001 and "Desktop RP Cuts Costs and Improves Design," August 2002) and in some cases eliminate them altogether.
There are some caveats to solid modeling as well.
- CAD software functionality of any type may tie the designer's and engineer's hands with limitations in functionality or impediments to using that functionality.
- Using concept models exported from industrial design programs such as Alias|Wavefront's Alias Studio (figure 1) and other non-CAD programs can be tricky.
- Learning to use 3D CAD software takes time, and solid modeling can be time consuming, even though it allows downstream activities to be far more automated.
- Photorealistic images of models may mislead casual observers into thinking the product is more developed than it really is.
- Computer representations can't fully address every ergonomic issue of the product, so prototypes may still prove necessary.
Despite these and other drawbacks, experience shows that the advantages of art-to-part substantially outweigh the disadvantages.
Who's who in MCAD
CAD software is evolving into a more complete, mature, and useful family of products. To expand on our direct art-to-part experience, we interviewed CAD vendors to get their viewpoints on the most important developments in the past two years. These companies sell many types of software, yet you can still safely call them CAD companies. They have different strategies and frequently influence each other in both direct and indirect competition-though they are sometimes reluctant to admit or realize it.
Autodesk expanded its ubiquitous AutoCAD with solid modeling and surface capabilities via Mechanical Desktop which in turn sold quite well. It then developed a better system, Autodesk Inventor, from the ground up. Inventor is now Autodesk's prime 3D program for manufacturing. Autodesk continues to support Mechanical Desktop. For 2D mechanical users, Autodesk will continue developing AutoCAD Mechanical.
SolidWorks (company and product) was acquired by Dassault Systemes as Dassault developed its newer Windows-based CATIA V5 to gradually replace its ancient yet widely adopted UNIX-based CATIA V4. SolidWorks continuously pushes for an improved program to benefit the average CAD user. However, the only contribution you'll find SolidWorks making to Dassault is on the financial statements. No significant integration announcements have been made regarding SolidWorks and CATIA.
Solid Edge, originally developed by Intergraph, was sold to UGS (Unigraphics Solutions), which later bought SDRC (including its high-end I-DEAS Master Series CAD software). EDS, the largest shareholder of UGS, essentially brought all of these products under its roof. Unlike Dassault, it has announced and developed numerous integration plans between its various programs. It intends to merge Unigraphics and I-DEAS-originally competitive products. Solid Edge remains a viable midrange application that offers true interoperability with Unigraphics.
|Figure 2. Pro/ENGINEER Wildfire offers unprecedented connectivity through Web-enabled technology, a Windows-style interface, consolidated menus, dashboard, and slide-out menus.|
Hard-charging PTC, the maker of Pro/ENGINEER, acquired numerous other vendors and integrated their applications. Of the high-end CAD programs, Pro/ENGINEER has felt the greatest pressure from midrange products, which appeal to those in its user base who are not using its advanced functionality.
Though a base version of Pro/ENGINEER has been available at midrange pricing for years, it's only with the completely overhauled and recently introduced Pro/ENGINEER Wildfire (figure 2) that the product became simple enough for casual users and lower-end tasks, according to PTC.
Where are we headed?
In the past, we've seen art-to-part tools that simply could not deliver for even the most determined users. We asked vendors whether the key constraint for the art-to-part process has been limits in technology or justifying the required change in process to users.
The 2D paradigm is giving way to 3D solids as the predominant standard for manufacturing, according to Autodesk's vice-president of manufacturing, Robert Kross. Of course there will still be many 2D users, and the company will continue to produce AutoCAD Mechanical for them. Kross sees ease of use as 3D's main limitation. The question 2D users face, Kross emphasizes, is whether their goal is to produce a drawing or a product. Naturally, the product is their goal, and 3D trumps 2D in that regard. Though customers aggressively use basic functionality, he noted that most have yet to embrace a full product model environment that encompasses lifecycle issues.
Applications that readily plug in to existing processes are adopted quickly, explained SolidWorks' vice-president of marketing, Ilya Mirman. Ten percent of the company's user base lets the software automatically report use statistics for the various elements of the program. From these statistics, it appears that SolidWorks' eDrawings view and markup program is used by half of its user base at least once per week.
|Figure 3. SolidWorks e-drawings and markup capabilities can assist in across-town or worldwide collaboration and communication.|
Mirman says that the popularity of eDrawings for both SolidWorks and Autodesk files (millions of each) is because it fits into the existing processes of sending paper drawings and drawing files, but in a better way-with small file size and a built-in viewer (figure 3).
Many communications issues among engineering, manufacturing, and suppliers are not made easier by the increasing globalization of teams that work on digital products before manufacturing starts on the physical products.
PTC gets credit for initiating the widespread shift in CAD to the parametric solid modeling paradigm. For all of the vendors, exploiting solid modeling directly with related applications has been less successful. So they've come up with other ways to use available technology. One example is PTC's promotion of design reviews over the Web and the use of free, hosted project collaboration "rooms" where teams can centralize their efforts without the help of a PDM (product data management) system.
PDM hasn't been implemented enough to fully drive the master model concept that is talked about so much in high-end CAD. What's proven important is that applications must work together. Program integration is not enough, says EDS' vice-president of marketing, David Primrose. EDS perhaps knows this better than anyone after integrating numerous CAD, CAM, and CAE applications from its acquisitions and development efforts. The company has produced a wealth of strong applications, yet few organizations have fully exploited them all the way through their own processes.
Mistakes in the design phase have the most impact, and the amount of subsequent rework downstream is still substantial, according to Primrose.
The numerous CAD and other files generated from design activities should ideally be kept within a PDM system that provides at least document control and some workflow management. Some programs track individual product elements with detailed configuration management tools for specific industries, such as aerospace.
The concept of PLM (product lifecycle management) has produced a confusing acronym soup, according to industry observer Brad Holtz at Cyon Research. PLM makes both new and old design data, the lifeblood of a company, available to a wider audience. With this information at hand, everyone from marketing to customer service can use and view the data. This goes to the heart of a company's operations and so requires serious attention from upper management as well as the engineering department.
Traditional PLM software solutions are primarily targeted at larger manufacturers with larger databases and greater numbers of people to coordinate. The big manufacturing CAD vendors (Dassault, EDS, and PTC) provide PLM solutions today, and Autodesk is working on one. As you might guess, PLM's scope is beyond that of this article.
|Figure 4. Whether the design helps the product function or merely gives a plain box some character, art-to-part shapes the way we interact with all types of products. This eye-catching concept was intended to draw attention to an otherwise mundane product.|
Industrial design expands
The concept stage of consumer-related products often requires aesthetically appealing styles that increase sales but don't necessarily improve function. Today, the flowing lines and surfaces in the art can be iteratively adjusted between design and engineering to produce more functional benefits than ever before. Some examples of this include ever-shrinking product sizes, improved ergonomics, enhanced fluid flow, and reduced stress (figure 4).
Because visual appearance has traditionally been very important, the initial design shape is often crafted by a dedicated industrial design person or team separate from the engineering design team. These two groups usually use different programs with different model formats to accomplish their individual tasks.
|Figure 5. Example of loft using multiple rails in Autodesk Inventor 6.|
The complex shape description capabilities of today's midrange and high-end CAD systems now include powerful surfacing functions that are well integrated with the core solid modeling capabilities. One result is a wider proliferation of artfully designed products as the many engineers without industrial design partners have increased visual appeal and function on their own (figure 5).This trend extends from consumer products to industrial products.
One ramification of the increasing shape sophistication in common models is that many CAM shops have had to upgrade their capabilities from 2.5-axis to 3-axis machines. Shapes that are impossible to machine manually are now milled or tooled with ease. The integrated photorealistic rendering capabilities in CAD programs are so good that many companies bypass additional work on their models for presentation purposes. Product renderings can help win sales.
|Figure 6. This 3D conceptual model, along with a color-changing 360° interactive animation, was developed in two days using Alias|Wavefront. Visualization aids and timetables like this are hard to compete with.|
Despite these CAD capabilities, CAD software users still need to be unbelievably imaginative and very patient. They jump through a lot of hoops in attempts to produce or reproduce geometric features that are often trivial to create with industrial design programs such as Alias|Wavefront and Rhino. Alias Design Studio is almost a de facto standard among industrial designers, especially in larger firms (figure 6). See Cadalyst's review, October 2002, p. 36.
The third-party integration of conceptual, design, and surfacing software has not made the same kind of progress as analysis, quality, and manufacturing software packages. This is due to fundamental differences in the geometric foundation of the industrial design applications. Why is this problematic?
- It forces companies to maintain disparate databases.
- Data may need to be recreated in the CAD system, which can be very time consuming, especially if several iterations come from industrial design.
- Translations are required for engineering and industrial design to communicate. Though data exchange has improved, large file sizes and other problems abound.
- Designers may end up having their hands tied by inferior user interfaces that are cheap copies of more popular and efficient originals.
Alias has responded by recently adding direct translation capabilities for most of the major CAD programs. EDS sells an alternative industrial design program called Shape Studio in the same $20,000 price range as Alias. Shape Studio is based on its Unigraphics CAD application so additional translations are not required. PTC's competitive answer is to incorporate its previous stand-alone CDRS industrial design functionality into Pro/ENGINEER via its interactive surface design extension (ISDX). PTC is also releasing a fairly low-priced conceptual design and communication tool called Pro/CONCEPT to complement Alias and other industrial design programs.
Strong CAD Performance
Large-size assembly performance has inevitably improved with faster processors and better code. High-end CAD programs such as Unigraphics have offered very good performance in this regard for some time. Assembly performance has dramatically improved in midrange programs and remains a hot topic for comparisons and claims.
Graphical user interfaces have prevailed over menu-based interfaces, and additional refinement in terms of context-appropriate commands and screen displays produced significant usability improvements for the many engineers who never had the time to become full-time CAD jockeys.
"Just in time" instead of "just in case" is how PTC explains the new interface for Pro/ENGINEER. We think the explanation applies to all good CAD interfaces today-most became graphical after I-DEAS yet before Pro/ENGINEER. Rather than providing every available command up front, they focus on showing the most essential commands so that users are not hit with a deluge of options and decisions to create a simple box. Of course, how well this fits your working style can vary quite a bit.
To expand design productivity further for the design group as a whole, the high-end vendors provide elementary but essential design rule checkers. These can also be purchased from third-party vendors such as PlanetCAD (now Avatech Solutions).
|Figure 7. Completed weldment design created in Autodesk Inventor 6s new weldment environment.|
PTC is expanding its behavioral modeling capabilities that help you choose the best set of variables to accomplish a given goal. EDS provides what it calls KBE (knowledge-based engineering). KBE encapsulates knowledge from related processes in analysis and manufacturing to guide engineers in their designs as they are designing them. One example is a convoluted spline (gear) expanded beyond its normal definitions to become a functional model with information about the speeds and forces it can handle when made from a given material.
All CAD vendors embrace the reality of heterogeneous CAD environments as part of everyone's extended realm of operations with outside suppliers and customers. Exchanging 3D geometry and topology is common (figure 7).
Several packages promote design communication via Internet technologies for internal engineering purposes such as PDM system access and part libraries, and external purposes such as project management.
|Figure 8. In Autodesk Streamline 4, texture and reflection mapping on 3D parts allows nondesigners to better understand 3D designs.|
Autodesk hosts the Streamline project Web site service (www.autodesk.com) that allows internal and external users to publish CAD files and other related data such as bill of material information for purchasing and assembly instructions for the shop floor (figure 8). The Autodesk/CADalog Part Library offers drag-and-drop functionality from a browser into Inventor models.
PTC's ProjectLink (www.ptc.com) application provides a centralized Web-based project room for teams to share and collaborate on all aspects of a design in a secure environment. This includes CAD files from all of the major vendors.
|Figure 9. SolidWorks centralized supplier and user model repository, 3D ContentCentral, on the Web.|
SolidWorks 3D Instant Web site (www.solidworks.com) publishes designs to the CAD vendor's hosted site from within the application. More significantly, the SolidWorks 3D PartStream.NET online fee-based catalog service enables manufacturers to build their own online component libraries that customers can access via the Web. A centralized clearinghouse of all the 3D PartStream.NET supplier catalog sites called 3D ContentCentral is available from within the SolidWorks application (figure 9). The clearinghouse will also include contributions from individual CAD users. The company's Manufacturing Network is a yellow-pages style listing of SolidWorks-enabled suppliers (figure 10).
|Figure 10. SolidWorks new Manufacturing Network Supplier Finder helps customers quickly find manufacturing suppliers who can accept their native SolidWorks files, which eliminates the need for data conversion.|
CAD packages typically include some basic analysis capabilities such as range of motion and interference checking that every designer can use and appreciate immediately. More advanced capabilities are less popular because they require finding someone qualified and experienced enough to run the more advanced analyses.
Full-time analysts often complain that analysis is done as something of a safety net for designs that are already frozen. They contend that analysis performed earlier in the design process can lead to product optimization instead of simply validating that nothing disastrous is likely to happen.
|Figure 11. Here you see a mold base in development in Pro/ENGINEER. You can adapt lessons learned from prior designs to new projects. This can be incredibly helpful and save time and effort.|
Several analysis vendors attempted to rectify this situation by providing simpler applications that design engineers can use on their own. The situation improved only marginally in the midrange field as the simplified processes yielded inadequate results, according to EDS' Primrose and others. If you want substantial results, you still need the dedicated analyst with the high-end tools.
Nonetheless, there are some exceptions to that trend. Mold analysis applications effectively encapsulate expert knowledge and influence designs in a timely manner (figure 11). Deflection analysis performed inside the CAD system with an integrated CAE application such as COSMOSXpress inside SolidWorks can provide helpful results in one minute. A fair number of Pro/ENGINEER users perform integrated analysis with the optional Pro/MECHANICA program that provides converged answers-critical to less experienced users.
ANSYS is bridging the gap between simple and comprehensive analysis with its DesignSpace application. The program works with all of the CAD applications mentioned in this article except I-DEAS. DesignSpace allows CAE experts to leverage their expertise with the high-end ANSYS across more design engineers, earlier in the design process, through a controlled deployment of analysis routines.
Today's 3D models aid manufacturing by precisely defining numerous values that can't necessarily be determined from 2D models. Nongeometric information such as tolerances and material information is stored in the model. This can eliminate the need for drawings altogether. Unfortunately that's about as far as many CAD users go to help get information to manufacturing.
It doesn't have to be this way. There are huge benefits in using the integrated applications of the major vendors because of the full associativity. Manufacturing planning can begin before the design is fully complete-compressing lead times. Any last-minute changes in the design can be easily accommodated without starting the numerical control planning work all over.
Design rule and model quality checking programs can flag problematic design issues in the high-end programs.
CAM applications have matured, so production engineers are not without their own tools. Many programs automatically generate toolpaths and provide a wealth of fixturing functions. Feeding important lessons back to the design engineer remains sporadic in most cases.
A tremendous wealth of functionality is available in the programs sold by the vendors mentioned in this article. The high level of integration within application suites, and sometimes between them, is impressive. The tools can streamline existing processes, and they can be used to develop even better processes, although this takes more initial effort. Don't wait for tomorrow's tools to develop your plan for where you can go today.
About the Author: Steven Weisberg
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