By Joe Greco
Not too long ago, when drawings were still done on paper, engineers used a combination of slide rules, calculators, and handbooks, as well as their years of training and experience, to formulate engineering solutions. As drawings migrated to the computer, a lot of these engineering tools didn't. Sure, FEA and motion-analysis programs have answered some engineering needs. But software with the "intelligence" to help solve design problems in engineering has not really existed.
Recently, however, a number of new CAD tools have been introduced that handle some of the thinking that goes into the design process. Here's a representative sample of the new "smart" programs that can help engineers solve problems across virtually all phases of the design process from conceptual design to final tooling.
Even with CAD software, most sketching is still done on napkins and pads with pencils. This is because while most CAD programs make it easy to create and edit the simple geometry that makes up an engineering sketch, until recently few could account for the movement of parts often so critical in a design. Essentially, most CAD and drawing programs lacked the tools necessary to do a 2D kinematic study of a machine design, for example.
While efforts have been made to include kinematics, one of the most successful implementations has been SmartSketch (formerly Imagineer) from Intergraph. With this software, users create sketches as rigid bodies and then control the relationships between these bodies by changing dimensions. Additionally, the sketchers found inside most 3D feature-based MCAD programs can also be used to develop engineering mechanisms. SolidWorks, Solid Edge, and Inventor have similar capabilities, with the latter providing the added benefit of assembling a series of 2D sketches into a more complex mechanism. Even after this early design stage, the kinematic design sketch still comes in handy to resolve miscellaneous details such as how pressing a button makes the door of a hand-held tape recorder pop open.
|The CoBrain.com Web site searches for patented solutions to design problems.|
Once the basic concept of the design starts to take place, some research may be necessary. Often a solution to a problem is already at hand, perhaps in the collective intellectual property of your company. However, reading through hundreds and perhaps even thousands of these documents can take weeks or months.
This is where CoBrain from Invention Machine comes into play by scanning any electronic documents you request and pulling out all the information relevant to the design problem. Users can also apply filters to reduce the amount of information retrieved. CoBrain searches the documents in a variety of formats, including Microsoft Word, RTF, HTML, and PDF, and from this data creates an expert Web portal. After going to CoBrain.com, you can type in a problem such as "cooling an engine," and the program will perform a search through US and foreign patents.
|Analysis of cost per part-in terms of material, setup, process, and tooling-can be done in Boothroyd Dewhurst's DFM Concurrent Costing software.|
Invention Machine also develops Knowledgist, which offers many of the same features as CoBrain, and performs a competitive analysis of patents owned by other companies or individuals. Features of the software include the ability to locate potential new markets for your technology and to perform an invention novelty test. This test helps companies determine whether or not they should develop or purchase new technologies.
After you learn that your design has not infringed on any existing patents and find out which existing technologies you can use, design for manufacturability and assembly (DFM/A) evaluations can commence. The purpose here is to determine if there are more cost-effective ways to build and assemble the components of your design, by rethinking factors such as the materials, manufacturing process, connections, and so forth. For instance, your design may consist of a multi-piece sheet-metal part. An evaluation may show that by bending a single piece rather than joining multiple pieces, you can produce a part that is slightly more expensive in terms of materials, but far less costly overall because of a savings in assembly labor. Alternately, if the part has to be made of separate pieces, perhaps snap fits can be used in place of traditional fasteners.
|Advanced analysis is available in the DFM Injection Molding module.|
These are areas of expertise that Boothroyd Dewhurst has built into two of its programs: DFM Concurrent Costing and Design for Assembly. Both are used early in the design process to help the engineer make smart decisions that will have major effects downstream.
Part of the Concurrent Costing package are three modules called DFM Machining, DFM Sheet Metalworking, and DFM Injection Molding. For designers and engineers who have limited machining knowledge, DFM Machining provides a visual library of machining processes, allowing users to estimate the machining cost of a part. The DFM Sheet Metal-working and DFM Injection Molding modules estimate the costs of making a component considering the relevant manufacturing processes.
Boothroyd Dewhurst also provides software for two relatives of DFM/A, known as Design for Service (DFS) and Design for Environment (DFE). Even though a product may be easy to assemble, it may not be easy to service. With that in mind, the DFS module generates a report that points out areas that should be examined for service improvement. DFE simulates the disassembly of products when their usefulness has expired and reports on the associated cost and environmental aspects of dismantling a design.
|One of the mechanical designer's most frequently referenced manuals, the Machinery's Handbook, can be accessed from SolidWorks 2000. |
Other relatives of DFM/A, such as design for flexibility (DFF), have not yet been addressed. DFF is a process that studies the impact a variation will have on the overall design, such as a bigger engine inside an automobile, and how to make that variation have a minimal effect on other components. SolidWorks has sophisticated techniques to show different assembly layouts, but it doesn't provide tools that evaluate your design and make suggestions about how it can be improved in terms of DFF.
CAD work usually begins when the user is ready to add the design details, and there are many fine programs that accomplish this task. But when working in CAD, many users are stuck with traditional reference materials and tools, including the Machinery's Hand-book and engineering calculators.
Fortunately, many components are standard parts, and some CAD software can use digital models of these. For example, SolidWorks and Inventor both include CAD representations of standard fasteners from the Machinery's Hand book as part of their software. Several programs from Autodesk can use the Web to access standard 3D content of products found in the Thomas Register. Vector Works offers the entire Structural Steel Handbook, allowing the user to pick various I-beams, channels, angles, and tees. Like the items in SolidWorks and Inventor, all of these symbols are parametric, meaning changing their shape is just a matter of entering a new value.
|By calculating part loads and sizes, Mechsoft helps engineers design spur gears (above) and other components.|
Autodesk's Mechanical Desktop (with the Power Pack) offers the engineer an array of standard parametric parts such as belts, pulleys, shafts, and gears. Users can also perform some simple analysis. This has been taken one step further by a European company called Mechsoft.com. Its software, Mechsoft, runs inside all major MCAD programs and allows users to employ its million-part library to build assemblies. The advantage is that these parts are intelligent; for example, the belt driven by a 5-hp motor will update accordingly if the motor is changed to 7.5 hp. It can also be used to calculate engineering alternatives. A new program from Applied 3D Science called ParaLogix offers many of the same tools.
Besides gaining access to reference handbooks and manuals, engineers can also now go way beyond the functionality of another familiar tool, the calculator. With GrafiCalc, users create or import 2D geometry and then apply engineering calculations to it. GrafiCalc can also be used to solve 2D kinematics problems, perform what-if analyses on various conditions, calculate beam deflections, design gears, and handle other chores.
TechOptimizer from Invention Machine specifies design problems in a model and offers potential solutions that can be tested inside the program, such as to improve the airflow of a vacuum cleaner. Two other products to help engineers solve design problems are iSight 5.5 from Engineous Software and Design ++ from Design Power.
High-end MCAD applications such as Pro/Engineer, Unigraphics, and Catia all offer technology designed to make engineers work smarter. For example, Pro/E's Behavioral Modeling concept can be used to optimize the volume of a tank, based on other given data such as surface area and material thickness. In Unigraphics and Catia, a component can be automatically updated as one aspect of a design is changed; for example, more ribs may be added when a plate is made larger.
|GrafiCalc can do a number of chores, including show the effect of a pulley system after one of the components has been moved.|
Recently, mid-range MCAD applications have been introduced that feature integrated intelligent analysis tools. For instance, in Solid Edge 8, sensors are set up to warn users if established design rules have been broken.
As a design takes form, thought must be given to tolerance analysis. Several products can help the user in this area. For example, with eMPower from Tecnomatix, when users import 3D MCAD files, the software evaluates whether they can be inspected. GrafiCalc also offers 2D tolerance analysis, and various plug-ins for both SolidWorks and Solid Edge are available.
The above tools are great, assuming you have a firm grasp of the subject matter. But suppose your design calls for silicon sealers, and you know nothing about them. This is where Web sites such as engineering-e.com come into play by putting users in touch with experts in various fields of engineering. Other such sites include prodeveloper.net from CollabWare and Autodesk's PointA.
While collaboration software is big these days, several MCAD programs have taken the initiative and either built an entire CAD program around collaboration or made it a part of their application. Alibre from Alibre Inc. and GS-Design from CollabWare fulfill the former definition, while Inventor and SolidWorks use Microsoft's NetMeeting to allow a virtual session to take place. While these sessions are usually intended for design reviews, they can also be used by a designer to get some advice from an expert in a given field.
|Sites like engineering-e.com allow users to locate experts in fields such as structural analysis and heat transfer.|
Evaluating a part and knowing where it should be split for molding purposes requires a great deal of experience. For these mold makers, there is Magic RP from Materialize. The company offers a Rapid Tooling module that reads in almost any 3D CAD file and, after determining the parting line, builds the core and cavity, including cooling channels and alignment holes. Cimatron's QuickSplit, DelCam's PowerShape, and Unigraphics Solutions' Mold Wizard also offer tools that assist the mold designer by automatically creating the tooling.
These are just some of many new applications that help engineers make hundreds of decisions concerning a product's function, shape, material, and manufacturability. Expect this list to get longer as computers get faster and software more intelligent.
Joe Greco is a freelance writer specializing in computer-aided design. He can be reached at Joe3D@home.com.
Alibre Design Alibre
Catia Dassault Systemes
GS Design, Prodeveloper.net
Inventor, Mechanical Desktop
Applied 3D Science