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The Importance of Drawing
in the Mechanical Design Process
Computer & Graphics Vol.14, No. 2, pp. 263-274, 1990
Pergamon Press plc.
David G. Ullman E-mailUllman
Department of Mechanical Engineering
Oregon State University
Corvallis, Oregon 97331
This paper is a study on the importance of drawing (both formal drafting and informal sketching) during the process of mechanical design. Five hypotheses, focused on the types of drawings, their necessity in mechanical problem solving, and their relation to the external representation medium, are presented and supported. Support is through referenced studies in other domains and the results of protocol studies performed on five mechanical designers. Videotapes of all the marks-on-paper made by designers in representative sections of the design process were studied in detail for their type and purpose. The resulting data is supportive of the hypotheses. These results also give requirements for future computer aided design tools and graphics education, and goals for further studies.
The goal of this paper is to study the importance of drawing (both formal drafting and informal sketching) in the process of mechanical design. This goal can be extended to state that we intend to show the necessity of drawing during all the developmental stages of a mechanical design. Through the information presented here, the requirements for future computer aided design tools, graphics education, and further studies will be developed.
All mechanical engineers are taught drafting. Thus, most engineers are skilled at making and interpreting these formal mechanical drawings. These drawings are representations of a final design (the end product of the design process) and they are intended to archive the completed design and communicate it to other designers and manufacturing personnel. Additionally, engineers are notorious for not being able to think without making "back-of-the-envelope" sketches of rough ideas. Sometimes these informal sketches serve to communicate a concept to a colleague, but more often they just help the idea take shape on paper. It is in considering how these sketches help an idea take form that gives a hint that drawing's role in engineering is more than just to archive a concept or to communicate with others.
Understanding the use of both drafting and sketching in design is important to help formulate the future development of Computer Aided Design or Drafting (CAD) systems. As CAD evolves and becomes more "intelligent," the question of what attributes these systems must have becomes more important. In the past CAD system attributes have primarily been driven from developments in the computer industry. It is only through understanding drawing's importance in the design process that these systems can be based on design needs.(1) Additionally, the pressures of CAD tool development, faculty time demands, and course expenses cause academic institutions to reevaluate the content of their "graphics" courses. Understanding drawing's importance in the design process helps establish what skills need to be taught to engineers during their training.
This paper is organized by first, in Section II, clarifying the types of drawings used in mechanical design. The hypotheses to be addressed in this paper are given in Section III. A discussion of research on the understanding of visual imagery to be used as a basis for arguments in support of the hypotheses is in Section IV. In Section V is a discussion of the results of data taken on how mechanical engineers use drawings during design. Lastly, in Section VI, is a discussion of how well the hypotheses have been supported and the implications of our findings on CAD development, educational requirements and future research directions.
II. TYPES OF DRAWINGS USED IN DESIGN
Engineers make many types of marks-on-paper. In...
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