History of CNC (Computer Numerical Research Paper

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Michael Cooley (1972) has suggested that the drawing office has been downgraded in importance as a result of the finer division of labor in engineering that began in the 1930s. He described how the creative design element had become increasingly separated from the work of executing drawings. The fragmentation of shop floor jobs was, according to Cooley, paralleled by fragmentation of the job of the designer/drafter. Until the 1930s, drafters in Britain were responsible for designing a component, stress testing it, selecting materials for it, writing the specifications, and liaising with the shop floor and customers. But starting in the 1930s, these functions were progressively broken down into separate jobs and taken over by various specialists, such as stress testers, metallurgists, tribologists, methods and planning engineers, and customer liaison engineers, leaving drafters with only the job of drawing (3D Systems Corporation, 2001).

In effect, in the Britain of the 1930s, drafters filled a general-purpose professional engineering and design role. As the whole process of design became more complex, the role of the drafter was split into higher functions -- the specialists Cooley mentions, together with University graduate engineer designers -- and lower level jobs -- principally, drafters and support technicians. Cooley criticized the whole process of specialization and division of labor, which he termed fragmentation, on which the industrial development of the past two hundred years has been based. He writes nostalgically of the millwright who "was capable of repairing any machine in the plant in which he worked. He could predict the failure rate of bearings, select the material for new ones, and in most cases manufacture them himself." By contrast, he argued, "CAD tends to de-skill the designer, subordinate the designer to the machine and give rise to alienation. Indeed, most computerized design environments begin to display those elements which are regarded as constituting industrial alienation, in particular powerlessness, meaninglessness, and loss of self and normality" ( 1987, p. 40).

Chapter Three -- Results and Findings

Evidence supporting such views was provided by Chris Baldry and Anne Connolly on the basis of a study of seven leading CAD users in Scotland in the early 1980s (Lester, 2008). They found that much CAD work was repetitive and routine, involving details and enlargements of existing designs. Groups of drafters often worked on the same drawing, and few operators had the satisfaction of producing a complete drawing themselves. Operators had lost some elements of control over their work. The CAD system produced all drawing, labeling, and dimensioning in a standard format. Indeed, standardization of design is often a direct consequence of CAD use because CAD works most effectively if a library of standard parts and components is constructed in the computer's memory. Similarly, Kaplinsky (1982, p. 110) found that operators and management agreed that CAD reduced the skill component in drafting because it removed the craft elements associated with individually tailored layouts and lettering.

McLoughlin (1989), however, challenged Baldry and Connolly's findings on the basis of his own more recent case studies. While Baldry, Connolly, and Kaplinsky had cited the loss of manual craft skills in drawing as evidence of de-skilling, McLoughlin found that the new mental skills needed to use CAD usually compensated for the loss of manual skills. In response to the standardization argument, he pointed out that design is, in essence, a three-stage iterative process of basic conceptualization, analysis of design options, and detailed design and drawing. Most of the CAD systems in use in Britain are drafting systems, essentially electronic drawing boards serving only the third phase. They enable users to manipulate two-dimensional drawings and annotate them. CAD systems are "shape processors" analogous to word processors, which aid writers but do not reduce the need for writing skills. In addition, McLoughlin notes the increasing use of modeling systems that support more directly the earlier, more creative phases. Computer models act as malleable databases from which drawings can be extracted and displayed. They allow designers to consider several design options in some detail before deciding on a final design. They can also provide data for downstream activities such as production and thereby eliminate a great deal of routine work in recopying drawings. According to McLoughlin, "Drawing by conventional means utilizes a number of craft mental skills in manipulating the pencil, and involves a direct relationship between the thought of a user to 'draw a line' and the act of drawing." When CAD is used, "The craft skills used in actual drawing are eliminated as lines of perfect quality and weight are drawn automatically by the system.

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The relationship between the user and the drawing thus becomes more indirect and abstract, requiring the exercise of mental skills in understanding the capabilities of the system and in selecting appropriate routines from the menu."

Our own interviews with a small sample of CAD users tended-with some exceptions -- to support McLoughlin's findings (Watson & Petre, 2000). One user commented that CAD made his work more routine, and some complained that CAD took away the satisfaction that could be derived from producing a good drawing. The more common view, however, was that CAD increased the skills required of the designer or drafter. The most common types of positive comment made about CAD were that it made the work more interesting and less routine, and that job prospects were liable to be better in companies using CAD. For example, one CAD user commented:

Working on CAD removes a lot of the tedium of the board but also offers more avenues for being creative. It feels like you are involved with a project rather than a drawing. Creativity is improved with the greater freedom offered through, for example, the ease of iteration and change, but it is limited by the level of expertise you can develop and the poor level of system development.

Another changed his unfavorable first impressions of CAD:

I thought it took away a drafter's skills. But, after learning to use CAD, I realized that the CAD "only draws pictures.' It does not take the skills of an engineer away; it enhances them. It does not take drafting skills away. You need drafting skills to produce good work on CAD. Advantages of CAD are that it is quick and you can do more complicated things. . . . CAD makes life easier. It would be a real pain to go back to the old ways of doing things.

CAD only began to affect British engineering firms in the late 1970s and early 1980s, and did not become really significant in British design and drawing offices until the mid- 1980s. Undoubtedly, engineering and design work has become much more specialized. It is doubtful, however, that the net result has been or will be de-skilling: There appears to be little evidence for Cooley's contention that CAD has de-skilled drawing and design work and would reduce the status of the drawing office still further. Indeed, our research in the early 1980s suggested that the "glamour" of CAD was likely to restore the status of the design function and to attract University graduates into design work (Meissner, 2006).

Chapter Four - Discussions

By the mid-1970s the introduction of all the major components for highly integrated, computer-driven manufacturing was well underway. Data collection, inventory control, production planning, CAE, and CAD/CAM applications were now the norm. Numerical control tools were the other components that linked planning to actual production of goods. They were widespread by the 1980s and virtually ubiquitous in the 1990s. The important development in this second period (1960s and 1970s) was the injection of computing into machining tools.

As noted before in this thesis, the earliest tools were highly inflexible, but with the introduction of microprocessor-driven tools in the early 1970s, now called computer numerical control (CNC), machines could be quickly instructed to change their operations. That new functionality drove down labor costs, increased flexibility, and shortened the time it took to cut and bend metal, for example. Mass producers could increase the variety of products they made without building new plants. By the end of the 1970s, these tools had sensing capabilities, which meant that they could alter operations in real time, an essential requirement for the effective use, say, of robots. The availability of sensing devices drove up the sale of robotic devices; in 1981 more were sold than in all previous years combined. With such capabilities in NC equipment, manufacturing firms could extend their automation sufficiently to begin creating flexible manufacturing systems (FMS), the basic new innovation evident in the late 1980s and through the 1990s. Computers could be used to design products, develop production schedules, and then instruct machines to make them. Logistics systems could then physically transport finished goods to warehouses or load them on trucks.

As recently as the early 1960s, manufacturing executives complained that NC machining tools were too expensive and cumbersome. The situation was unimpressive. Roy A. Lindberg, a mechanical engineering….....

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