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THE ORIGINS OF CAD/CAM

computer what is cad in

The use of computer modeling to test products was pioneered by high-tech industries like aerospace and semiconductors. The third source of CAD development resulted from efforts to facilitate the flow from the design process to the manufacturing process using numerical control NC technologies, which enjoyed widespread use in many applications by the mids.

The development of CAD and CAM and particularly the linkage between the two overcame traditional NC shortcomings in expense, ease of use, and speed by enabling the design and manufacture of a part to be undertaken using the same system of encoding geometrical data.

This innovation greatly shortened the period between design and manufacture and greatly expanded the scope of production processes for which automated machinery could be economically used. Computers are also used to control a number of manufacturing processes such as chemical processing that are not strictly defined as CAM because the control data are not based on geometrical parameters.

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 increasingly integrated.

This is of particular importance when one firm contracts another to either design or produce a component. Modeling with CAD systems offers a number of advantages over traditional drafting methods that use rulers, squares, and compasses. For example, designs can be altered without erasing and redrawing. CAD systems also 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.

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. Potential blockage of view corridors and shadow studies are also frequently analyzed through the use of CAD.

CAD has been proven to be useful to engineers as well. Using four properties which are history, features, parametrization, and high-level constraints. The construction history can be used to look back into the model's personal features and work on the single area rather than the whole model.

Parameters and constraints can be used to determine the size, shape, and other properties of the different modeling elements. The features in the CAD system can be used for the variety of tools for measurement such as tensile strength, yield strength, electrical or electromagnetic properties. Also its stress, strain, timing or how the element gets affected in certain temperatures, etc.

There are several different types of CAD, [9] each requiring the operator to think differently about how to use them and design their virtual components in a different manner for each. There are many producers of the lower-end 2D systems, including a number of free and open-source programs. These provide an approach to the drawing process without all the fuss over scale and placement on the drawing sheet that accompanied hand drafting since these can be adjusted as required during the creation of the final draft.

Each line has to be manually inserted into the drawing. The final product has no mass properties associated with it and cannot have features directly added to it, such as holes. The operator approaches these in a similar fashion to the 2D systems, although many 3D systems allow using the wireframe model to make the final engineering drawing views. Basic three-dimensional geometric forms prisms, cylinders, spheres, and so on have solid volumes added or subtracted from them as if assembling or cutting real-world objects.

Two-dimensional projected views can easily be generated from the models. Basic 3D solids don't usually include tools to easily allow motion of components, set limits to their motion, or identify interference between components. There are two types of 3D solid modeling. Top end systems offer the capabilities to incorporate more organic, aesthetics and ergonomic features into designs.

Freeform surface modeling is often combined with solids to allow the designer to create products that fit the human form and visual requirements as well as they interface with the machine. Originally software for CAD systems was developed with computer languages such as Fortran , ALGOL but with the advancement of object-oriented programming methods this has radically changed.

Typical modern parametric feature-based modeler and freeform surface systems are built around a number of key C modules with their own APIs. A geometry constraint engine may also be employed to manage the associative relationships between geometry, such as wireframe geometry in a sketch or components in an assembly.

Unexpected capabilities of these associative relationships have led to a new form of prototyping called digital prototyping. In contrast to physical prototypes, which entail manufacturing time in the design. That said, CAD models can be generated by a computer after the physical prototype has been scanned using an industrial CT scanning machine.

Depending on the nature of the business, digital or physical prototypes can be initially chosen according to specific needs. Currently, no special hardware is required for most CAD software. However, some CAD systems can do graphically and computationally intensive tasks, so a modern graphics card , high speed and possibly multiple CPUs and large amounts of RAM may be recommended.

The human-machine interface is generally via a computer mouse but can also be via a pen and digitizing graphics tablet. Some systems also support stereoscopic glasses for viewing the 3D model. Technologies which in the past were limited to larger installations or specialist applications have become available to a wide group of users.

CAD software enables engineers and architects to design, inspect and manage engineering projects within an integrated graphical user interface GUI on a personal computer system. Most applications support solid modeling with boundary representation B-Rep and NURBS geometry, and enable the same to be published in a variety of formats.

A geometric modeling kernel is a software component that provides solid modeling and surface modeling features to CAD applications. From Wikipedia, the free encyclopedia. See also: History of CAD software. See also: Comparison of computer-aided design editors. Lalit Computer Aided Design and Manufacturing. New Delhi: Prentice Hall of India.

Mailmax Pub. Clifton Park, NY: Delmar. Handbook of computer aided geometric design [electronic resource]. Schumaker eds. Archived from the original on

Computer-aided design (CAD) is a computer technology that designs a product and documents the design's process. CAD may facilitate the manufacturing. )Acronym for computer-aided design. A CAD system is a combination of hardware and software that enables engineers and architects to design everything from. Computer aided design (CAD) is a technological innovation that helps illustrate how tangible, physical work products become more abstract with increasing.

Computer-aided design, abbreviated as CAD, is the two-dimensional or three- dimensional modeling of physical structures and material. Computer-aided design (CAD) involves creating computer models defined by geometrical parameters. These models typically appear on a computer monitor as.

CAD (computer-aided design) software is used by architects, engineers, drafters, artists, and others to create precision drawings or technical illustrations. Computer-aided design, abbreviated as CAD, is the two-dimensional or three- dimensional modeling of physical structures and material.

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