Web-exclusive: Why switch to 3D (sidebar to 'Unlocking Design's Potential')

Editor's note: According to the industry experts at CADCAMNet.com, many companies are still wrestling with the question of whether or not to upgrade to 3D CAD systems and methods. In the following excerpt from “Justifying three-D design,” the authors give guidelines for finding out if 3D makes sense for your company.

Three-dimensional design differs fundamentally from two-dimensional processes. With 2D methods, drawings are the master documents that define how each part in a product should be made and illustrate how the product is assembled. The principal disadvantage of 2D methods is that it is hard to visualize how a 3D product looks from views projected on drawings. In contrast, 3D solid modeling software is used to create a three-dimensional computer mockup of the product before any drawings or prototypes are made. The 3D computer model, not the drawing, is the master.

Drawings can be made from the 3D CAD file to assist factory workers and planners. Drawings can be produced much more quickly from 3D models than by manual or computer-aided drafting techniques. Errors in projecting views that are common in 2D drafting can't occur when computers project views from unambiguous three-dimensional product models. Changes to drawings can be made much more quickly in 3D CAD processes because a single change made to the 3D master model updates all drawing views with perfect accuracy.

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 3D 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 3D.

The ability to employ 3D 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-dimensional 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.

A number of CAD systems are intended for designing in three dimensions using primarily what are called “solid” computer models. Such products include Catia V5, Pro/Engineer, Unigraphics NX, SolidWorks, Solid Edge, Autodesk Inventor, CoCreate Solid Designer, and VX CAD (formerly Varimetrix).

Manufacturers should invest in 3D 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:

o What is the cost of correcting mistakes in the shop caused by incorrect or ambiguous drawings?

o What is the cost of reworking prototype and production tools because changes are made after the first article is delivered?

o Could tool suppliers provide faster deliveries if your company gave them 3D CAD models instead of drawings?

o Do your customers expect your firm to design in 3D or deliver 3D CAD models of products and subsystems in addition to physical prototypes?

o How much money could your company save by inspecting products against 3D master models?

NOTE: This article, originally published Sept. 4, 2003 on CADCAMNet, was excerpted with full permission from CAD/CAM Publishing. Readers of IMM can log onto www.cadcamnet.com for a one-month free trial subscription to CADCAMNet.