CAD/CAM | Computer-Aided Design And Manufacturing | Autodesk
Since both CAD and CAM use computer-based methods for encoding internal shape of a part is revealed, and to illustrating the spatial relationships among a. In this paper applications of CAD/CAM in the different area of design is described where CAD / CAM software . to illustrating the spatial relationships among a. CAD (Computer Aided Design) is for creating digital simulations of 3D parts; most commonly this is associated with the ‘design’ of a part. CAM (Computer Aided Manufacturing) is for generating tool paths and other machine instructions that allow automated machine tools (like.
These models typically appear on a computer monitor as a three-dimensional representation of a part or a system of parts, which can be readily altered by changing relevant parameters.
CAD systems enable designers to view objects under a wide variety of representations and to test these objects by simulating real-world conditions. These systems differ from older forms of numerical control NC in that geometrical data is encoded mechanically.
Since both CAD and CAM use computer-based methods for encoding geometrical data, it is possible for the processes of design and manufacture to be highly integrated.
The first of these sources resulted from attempts to automate the drafting process. These developments were pioneered by the General Motors Research Laboratories in the early s. One of the important time-saving advantages of computer modeling over traditional drafting methods is that the former can be quickly corrected or manipulated by changing a model's parameters.
The second source of CAD's origins was in the testing of designs by simulation.
The use of computer modeling to test products was pioneered by high-tech industries like aerospace and semiconductors. The third influence on CAD's development came from efforts to facilitate the flow from the design process to the manufacturing process using numerical control NC technologies, the use of which was widespread in many applications by the mids.
Numerical control NC of automated machinery was developed in the early s and thus preceded the use of computerized control by several years.
How CAD/CAM Programs Work
Like CAM, NC technologies made use of codified geometrical data to control the operations of a machine. The data was encoded by punch holes on a paper tape that was fed through a reader, essentially the same mechanism as that on a player piano. Once the control tape was produced, it offered a reliable means to replace the skilled machinists that had previously operated such machines.
From the firm's point of view, the drawback of the old NC technologies was the difficulty in converting the design for a three-dimensional object into holes on a tape. This required the services of a tape encoding specialist. Since this specialist was required to work without any significant visual feedback, work was essentially trial and error and could only be tested in the actual production process.
The tape encoder had to account for a large number of variables, including optimal feed rates and cutting speeds, the angle at which the tool should contact the part, and so on. Given the considerable time and expense involved in NC technologies, it was only economically viable when a large number of parts were to be produced.
The development of CAD and CAM and particularly the linkage between the two overcame these problems by enabling the design and manufacture of a part to be undertaken using the same system of encoding geometrical data. This eliminated the need for a tape encoding specialist and greatly shortened the time between design and manufacture.
Computers are also used to control a number of manufacturing processes that are not defined as CAM because the control data are not based on geometrical parameters. An example of this would be at a chemical processing plant. Using CAD it is possible to simulate in three dimensions the movement of a part through a production process. This process can simulate feed rates, angles and speeds of machine tools, the position of part-holding clamps, as well as range and other constraints limiting the operations of a machine.
The continuing development of the simulation of various manufacturing processes is one of the key means by which CAD and CAM systems are becoming more tightly integrated. This is of particular importance when one firm contracts another to either design or produce a component. Designs can be altered without erasing and redrawing. CAD systems offer "zoom" features analogous to a camera lens whereby a designer can magnify certain elements of a model to facilitate inspection.
Computer models are typically three-dimensional and can be rotated on any axis, much as one could rotate an actual three dimensional model in one's hand, enabling the designer to gain a fuller sense of the object.
CAD systems also lend themselves to modeling cutaway drawings, in which the internal shape of a part is revealed, and to illustrating the spatial relationships among a system of parts. To understand CAD it is useful to understand what it can't do. CAD systems have no means of comprehending real-world concepts, such as the nature of the object being designed or the function that object will serve.
CAD systems function by their capacity to codify geometrical concepts. Thus the design process using CAD involves transferring a designer's idea into a formal geometrical model. In this sense, existing CAD systems can't actually design anything, but can provide tools, shortcuts, and a flexible environment for a designer to work with. Other limitations to CAD are being addressed by research and development in the field of expert systems. This field derived from research done on artificial intelligence.
One example of an expert system involves incorporating information about the nature of materials—their weight, tensile strength, flexibility and so on—into CAD software. By including this and other information, the CAD system could then "know" what an expert engineer knows when that engineer creates a design.
CAD systems have no means of comprehending real-world concepts, such as the nature of the object being designed or the function that object will serve. CAD systems function by their capacity to codify geometrical concepts. Thus the design process using CAD involves transferring a designer's idea into a formal geometrical model. Efforts to develop computer-based "artificial intelligence" AI have not yet succeeded in penetrating beyond the mechanical—represented by geometrical rule-based modeling.
Other limitations to CAD are being addressed by research and development in the field of expert systems. This field is derived from research done in AI. One example of an expert system involves incorporating information about the nature of materials—their weight, tensile strength, flexibility, and so on—into CAD software.
By including this and other information, the CAD system could then "know" what an expert engineer knows when that engineer creates a design.
The system could then mimic the engineer's thought pattern and actually "create" more of the design. Expert systems might involve the implementation of more abstract principles, such as the nature of gravity and friction, or the function and relation of commonly used parts, such as levers or nuts and bolts.
Such futuristic concepts, however, are all highly dependent on our abilities to analyze human decision processes and to translate these into mechanical equivalents if possible.
One of the key areas of development in CAD technologies is the simulation of performance. Among the most common types of simulation are testing for response to stress and modeling the process by which a part might be manufactured or the dynamic relationships among a system of parts. In stress tests, model surfaces are shown by a grid or mesh, that distort as the part comes under simulated physical or thermal stress. Dynamics tests function as a complement or substitute for building working prototypes.
The ease with which a part's specifications can be changed facilitates the development of optimal dynamic efficiencies, both as regards the functioning of a system of parts and the manufacture of any given part. Simulation is also used in electronic design automation, in which simulated flow of current through a circuit enables the rapid testing of various component configurations. The processes of design and manufacture are, in some sense, conceptually separable.
Yet the design process must be undertaken with an understanding of the nature of the production process. It is necessary, for example, for a designer to know the properties of the materials with which the part might be built, the various techniques by which the part might be shaped, and the scale of production that is economically viable.
The conceptual overlap between design and manufacture is suggestive of the potential benefits of CAD and CAM and the reason they are generally considered together as a system. Another important trend is toward the establishment of a single CAD-CAM standard, so that different data packages can be exchanged without manufacturing and delivery delays, unnecessary design revisions, and other problems that continue to bedevil some CAD-CAM initiatives.
Finally, CAD-CAM software continues to evolve in such realms as visual representation and integration of modeling and testing applications.