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CAD Softwares:AMRCC member practitioner of this technology
CAD Overview Throw out your drafting pencils and T-square! Pencil drafting is history. Today's fast-paced design requires speedy revisions and accurate geometry that only CAD, Computer-Aided Design provides. CAD began with aircraft manufacturers who needed to calculate precise locations for airplane wing rivet holes. Newly available computer technology allowed engineers to rapidly calculate hole locations and print the data on reams of paper. Painstakingly the hole locations were manually located and punched in the expensive sheets of aluminum. 
Interfacing the computer with a punch machine eliminated most slow manual labor and costly human error. This was the advent of CAD/CAM, Computer-Aided Design/Computer-Aided Machining. Today CAM is commonly referred to as CNC, Computer Numeric Control. Although computers were virtually error-free, glitches in programming or the interface problems occasionally resulted in unforeseen and usually costly scrap. Once again technology came to the rescue. Connecting a television monitor to the computer allowed graphing data to a visual image of the finished part. Errors were easily seen and corrected. Other manufacturing executives and engineers noticed the cost savings in time and material. CAD programs developed by aircraft manufacturers were sold to software companies who adapted CAD to all design fields and created user-friendly interfaces. CAD use immediately spread globally and became a lucrative market for software developers. 
Two and three-dimensional CAD drawings (models) contain all the equations for the geometry. Since CAD is a visual database the designer can query the database for any model information. Distance, coordinate geometry, volume, and mass properties are only a click away. Often designers in remote locations work together on the same model through networks or the Internet. The engineer discusses the design with the mold-maker across the country as they both mark-up features on the same model in real time. Today architects, mechanical engineers, electronics engineers, CNC machinists, civil engineers, interior designers, even artists utilize CAD to assist their design process to visualize their final design in real-time animated 3D space. Data from CAT scans converted to CAD give doctors the unique opportunity to view patients' internal organs and even model replacement joints before surgery. Exchange of electronic drawings and specifications simplify the design process. Instead of "re-inventing the wheel" the designer downloads the necessary part drawing for an assembly directly from the manufacturer's web site. The designer is assured of availability of the part and its fit and function. The manufacturer supplied the exact data and is verified as the supplier without tedious searching and ordering samples. Revisions made to CAD drawings are delivered to the users electronically attached to email. Instantly received, drawings are viewed or sent directly to the machining center. Parts are made without delay or need for interpretation. There no need to handle, file and store paper drawings. Computer files eliminate the need to make blueprint or photocopies. If a paper copy is needed, a new original is printed from CAD with the latest revisions. Advances in rapid-prototyping equipment allow the designer to plot a 3D object directly from CAD. A real object is created layer upon layer in various materials. These prototypes can be examined or used to make molds for the casting process. Due to advances provided by CAD, it is possible to realize what could previously only be imagined. Who knows, maybe science fiction's replicators are in the near future. Justifying three-D design September 4, 2003 -- Many companies are still wrestling with the question of whether or not to upgrade to three-dimensional CAD systems and methods. Two-D CAD methods have been in use at some firms for 10 to 20 years. Many have optimized their CAD software to automate a variety of two-D drafting functions. Some applications, such as drawing wiring schematics, are inherently two dimensional, so three-D systems can’t replace these altogether. This article is intended to help companies who still employ two-D decide whether three-D is right for some or most of their design work. It also explains how to justify three-D design financially, if your company needs it. The three-D design process Three-dimensional design differs fundamentally from two-dimensional processes. With two-D methods, drawings are the master documents that define how each part in a product should be made and illustrate how the product is assembled. Drawings may be made on a drafting board or with a CAD system such as AutoCAD, CADAM, Cadkey, Medusa, or ME-10 that’s used to made digital equivalents of drawings.
Three-D models made with Pro/Engineer can help engineers check assemblies for proper fit before prototypes are made. (Click image for a larger view.) The principal disadvantage of two-D methods is that it is hard to visualize how a three-D product looks from views projected on drawings. Consequently, designers sometimes supplement drawings with shop-fabricated physical prototypes in order to check drawing accuracy and solve problems. With industrial machinery, the prototype may be the first or only delivered article. Mistakes in drawings or the interpretation of drawings must be corrected in the physical machine, a process that can be slow and costly. In contrast, three-D solid-modeling software is used to create a three-dimensional computer mockup of the product before any drawings or prototypes are made. The three-D computer model, not the drawing, is the master. Three-D computer models from the digital mockup are used for many purposes including:
Drawings can be made from the three-D CAD mockup to assist factory workers and planners. Drawings can be produced much more quickly from three-D models than by manual or computer-aided drafting techniques. Errors in projecting views that are common in two-D drafting can’t occur when computers project views from unambiguous three-dimensional product models. Changes to drawings can be made much more quickly in three-D CAD processes because a single change made to the three-D master model updates all drawing views with perfect accuracy.
In this example, energy flow and temperature distribution in a heat-sink are simulated with MSC Visual Nastran V5i. The geometry was created in the CATIA V5 CAD/CAM software. (See "Maximize your benefits from analysis" for more discussion. Click image for an enlarged view.) Three-D CAD is especially productive for making sheet-metal structures. Three-D models of the formed sheet metal can be used to check fit in three-D assemblies. Then CAD software can automatically create flat patterns of sheet-metal parts that can be used in programming NC punches and on shop drawings. Three-D models can be used to quickly generate realistic renderings of products for use in sales presentations or reviews with marketing departments. With two-D methods, artists must begin renderings with a blank screen or sheet of paper. Rendering aids that come with three-D CAD software enable artists to employ geometry from existing product models. The artists need only add surface textures, lighting effects, and backgrounds to make a completed image. And if the product model changes, the rendering can be updated in minutes. With two-D drawing software or physical media, the artist must generally recreate the whole drawing following a significant design change. Economic benefits of three-D design
Three-dimensional CAD modeling has become the accepted method for designing automotive and aerospace products and systems because it offers persuasive economic benefits. When designing with three-D CAD software, mistakes can be identified and corrected before the product reaches the manufacturing stage. The ability to spot interferences, inaccurate dimensions, components that are inaccessible for maintenance purposes, and arrangements that can’t be assembled efficiently saves manufacturers many times the incremental cost of designing in three-D. The ability to employ three-D models for physical analysis, NC programming, and inspection reduces the time and cost needed to perform these tasks, making them more economical while improving product reliability, fit, and safety. Three-D master models also reduce drawing costs by automating view creation and eliminating the need to show as many cross-sectional views as would be needed in a purely two-dimensional approach. Costs of implementing three-D methods A number of CAD systems are intended for designing in three dimensions using primarily what are called "solid" computer models. Such products include CATIA version five, Pro/Engineer, Unigraphics NX, SolidWorks, Solid Edge, Autodesk Inventor, CoCreate Solid Designer, and VX CAD (formerly Varimetrix). The distinction between these solid-modeling systems and older systems such as AutoCAD, Cadkey, CADDS 5, Medusa, and CATIA version four has been somewhat blurred by the fact that the two-D drafting capabilities of the older systems have been augmented with solid-modeling, three-D wire frame, and three-D surfacing tools. In spite of these improvements, few companies have successfully employed three-D design methods using software originally developed for drafting in the late 1970s and early 1980s. Most successful three-D designers have employed more modern software developed in the late 1980s and 1990s. Firms that are now employing mainly two-D CAD methods will almost certainly need to invest in new software, upgraded computer workstations, and training in order to take advantage of three-D engineering processes. Even after training is complete, it will take designers months, if not years, to become proficient with three-D modeling. Expect and plan for some reduction in productivity as new methods are phased in. Some companies may need to upgrade personnel as well. Not all computer-aided drafters can master three-D modeling. The costs of recruiting and hiring new people may well equal the cost of hardware and software, especially for medium-priced systems. Right for your company? Manufacturers should invest in three-D design systems only if benefits exceed the costs by an amount sufficient to justify the capital investment. To estimate the benefits for your company, start by answering these questions:
Quantifying the savings from each of these activities is a complex exercise that requires gathering information from multiple departments. Each company is unique and not every one will find savings in every category. If, for example, you company rarely revises drawings, can completely detail its products in only two or three primary views, and has no need for analysis, automated inspection, or rapid prototyping, it may not need three-D CAD. Moreover, despite improvements in user interfaces, three-D systems remain fiendishly complex. Designers can struggle for hours trying to figure out why part features become dissociated from each other or why the software can’t model physically realizable details. The cost of working with this difficult and sometimes unreliable CAD software must be offset by the benefits of the three-D models they produce. Some users of two-D CAD software claim they can produce drawings in less time than they could with three-D. In some cases, it is faster to make a pencil drawing than to make a three-D model. Three-D CAD rarely can be justified on the basis of drawing production alone. Unless your company can realize some of the other economic benefits of three-D design, it may be worth staying with two-D. Over time, we expect that CAD systems will continue to become easier to use. Reducing the learning curve will reduce the costs and risks associated with adopting three-D methods. To read this and other articles, sign up for a one-month trial subscription to CADCAMNet, the independent briefing service for managers of CAD, CAE, PDM, and rapid prototyping. Visit http://www.cadcamnet.com and click the trial subscription link in the upper right corner. System Philosophy's History vs. Non-history based In a history based system, the program remembers the order that features were constructed in, non-history does not. For instance in a history based system (ProE, SolidEdge, etc.) let's say cylinder A is built first, then block B is built on the face of the block, then a boss C is built on a face of block B. In a history based program block B cannot be deleted leaving only cylinder A with boss C attached to it. The program remembers that boss C was built after block B and was attached to it. If block B is removed the system no longer has a feature or face to attach boss C to and the model regeneration will fail. Tools with the ability to manipulate the history tree are usually supplied with these software's to allow the operator to trick the system by moving a feature to an earlier point in the history tree (telling the system that boss C was created before block B). This step may or may not allow the part to regenerate. Also, if the feature you want to remove was created early in the modeling of a complicated part, you may have to do extensive manipulation of the tree in many steps to allow you to make the desired change. In a non-history based system (CoCreate SolidDesigner) the software makes no distinction between which feature was created first. Modifications are allowed in any order. Constrained vs. Non-constrained In a constrained system, a sketch of a feature's shape is drawn and fully dimensioned. The sketch is dimensioned from existing datum's such as faces or centerlines to give the feature a location. The sketch is then extruded or turned to add material, or milled or punched into existing material to remove material, to create the solid feature. These constraints define specific datum's and relationships that can tie down design intent, but can also cause problems with modifications. For example if hole patterns or mounting pads are defined by their location from the sides of a square boss and that square boss needs to be modified to a round boss, the features lose their "anchor" and the model will not regenerate. The only way to make the change is to reroute the anchors or redefine the constraints. Also undesired results from a modification can be obtained. For example slots meant to break out on one end become pockets if the face they originally broke through is moved out. This is caused because the slot was dimensioned to break through the original face location. Unless you know what type of changes will come your way during the modeling process you can't build in flexible enough constraints to avoid these types of issues. Non-constrained systems allow you to model a shape without locking in dimensions to the shapes. They can be modified after the fact to specific dimensions, or the shape can be modified. Each system has its own advantages and disadvantages. Non-constrained, in most cases, can make design changes in a much shorter time if they would change the original shape, etc. that would have been locked in by the constraints of the constrained system. If constraints don't change, just vary in dimensions, the constrained system may be as fast or faster. The constrained system has the ability to lock in design intent. For example a hole can be defined as always having a specified clearance to a mating pin. Some Non-constrained systems have added the ability to add in design intent if so desired, but do not require it when it is not desired. As another comparison Non-constrained systems are more suited to rapidly changing design concepts, where the constrained system is more efficient at designs that are identical other than size variations. AMRCC member practitioner of this technologyThe companies listed below, are willing to discuss their hands-on CAD Software experiences with you. Please feel free to use the email contact feature below to notify them of your interest. You will be contacted by the company's expert with that software to address your questions at their first convenience. Company: Fisher Controls, Marshalltown, IA. CAD Software: CoCreate SolidDesigner/ME10 Other systems used past or present: Applicon Bravo, ProEngineer, STRIM. PDM system: CoCreate WorkManager Type of parts modeled: Machined parts, castings (sand, shell mold, investment, permanent mold, etc. Aluminum die castings), injected plastic parts. Applications for CAD data: 2-D documentation for detail and limited dimension drawings. 3-D models and assemblies of full product. Full draft and blending for tooling creation is included in cast and molded parts. 3-D models are used for:
For additional information from this current user, contact: Fisher Company: HON INDUSTRIES, Muscatine, IA HNI Corporation includes: HON Company, Allsteel, Gunlocke, Maxon, Holga, HON International, Heat-N-Glo, Heatilator, Aladdin. CAD Software: PTC Pro/ENGINEER Other systems used past or present: SolidWorks, AutoCAD, Mechanical DeskTop PDM system: PTC Pro/INTRALINK Type of parts modeled: Sheet Metal, Molded Plastic, Wood, Castings, Fabric, Standard Fastener Hardware. Applications for CAD data: 3-D CAD Models used to create 2-D documentation for detail drawings. 3-D models and assemblies of full product. Full draft and blending for tooling creation is included in cast and molded parts. 3-D CAD models are used for:
For additional information from this current user, contact: HNI Corporation Click Service Providers to search Iowa companies by solution Search Useful Links to find manufacturers and suppliers of this technology. |
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