3 D Modeling/Gd&T Cornerstones For Manufacturing Education

Abstract

Three-dimensional (3D) modeling allows graphics to be taught as the virtual manufacturing of a part. Modeling of parts begins with a primitive – raw material. The primitive is then modified using features such as slots, pockets, holes, etc. – manufacturing methods. By using 3D modeling, students can be taught about both engineering graphics and manufacturing simultaneously; and thus have a better understanding of how to design parts for manufacturability. Geometric dimensioning and tolerancing (GD&T) encourages a dimensioning philosophy that defines a part based on how it functions in the final product. GD&T should be taught not merely as a set of symbols that are applied to a two-dimensional drawing, but rather as a functional requirement of the design, manufacture, and measurement of the part. While teaching GD&T the instructor should also incorporate fundamental concepts of metrology, which will provide students with a better understand of the “symbolic language” of GD&T and its affect on the manufacturing and inspection processes. GD&T and three-dimensional modeling both depend heavily on the use of datum planes and axes. By requiring students to be consistent in the application of datum planes/axes and location dimensions, the instructor emphasizes the importance of capturing design intent (manufacturing intent) in the model thus further enhancing the students understanding of the impact of design on manufacturing. This paper discusses the importance of three dimensional-modeling and geometric dimensioning as they relate to manufacturing and outlines a two-semester course sequence for presenting this material in a Manufacturing Engineering Technology curriculum. A Need to Follow the Change in Communication Models A survey by Clark and Scale of North Carolina State University 1 on current trends in technical graphics revealed that 54% of the respondents still teach manual drafting and that 92% of the respondents still teach two-dimensional (2D) CAD. The survey also revealed that only 54% of the respondents offered 3D constraint based modeling and that only 66% the respondents use some geometric dimensioning and tolerancing. It is not within the scope of this paper to address the pros and cons of continuing to teach manual drafting and 2D CAD. However, it seems clear that many programs have failed to keep up with the rapid technological changes in the technical