| MadSci Network: Engineering |
Dear Munish,
As you know from our e-mail correspondence, MadSci Network has given your question on the use of CAD/CAM in the electrical industry to me. In your e- mail you tell me that you are interested particularly in the use of this sort of software in the design and manufacture of electrical components such as transformers, motors, and other similar devices.
CAD/CAM, which stands for "Computer Aided Design / Computer Aided Manufacturing," refers broadly to software that allows engineers to use computers as they design things, move them into manufacturing, and then actually do the manufacturing. Electrical equipment of the kinds you are interested in are among the many kinds of products CAD/CAM can be used for. In this answer to your question will we'll discuss two of the most common kinds of CAD programs and then turn to a few of the more common (and important) CAM applications.
Typically when people think of CAD programs that think of those programs that help engineers accurately describe -- usually through drawings and diagrams -- what they are designing. At their simplest, these CAD programs provide an alternative, more productive way of doing technical drawing. So, instead of using rulers, tee-squares, pencils, and the other tools of traditional drafting to create drawings that capture the design of a motor, the design engineers can draw all the parts of the motor using the CAD drawing program. There are many advantages of doing this.
First, it is faster to use a CAD program to produce the initial drawings than it is to do it by hand. The program can automatically do much of the routine, but necessary work such as adding the lines and numbers that show the dimensions of the various parts of the motor. Similarly, CAD programs often have computerized "catalogs" of drawings of standard parts and subassemblies such as bearings and rotors. Instead of redrawing these standard items over and over the designer can just tell the CAD program to copy required items from the catalog into drawings. In diagrams that show the logical (as opposed to the physical) aspects of a design CAD programs can be especially useful. For example, schematic diagrams that show how components are interconnected in electronic circuits are much easier to produce with a CAD program than they are by hand. A big reason is that CAD programs can automatically redraw the lines connecting the components in the diagram when the components are moved around,r added, or deleted.
Second, and even more importantly, a CAD drawing program can save even more time when the design changes. Changing designs is much more common than you might guess. For example, suppose, while designing the motor, the design engineer selects particular bearings from the catalog and places them in the drawing. Once the drawing is done the design engineer sends it to the chief engineer for review. The chief engineer looks at the drawing and decides that the choice of bearings is wrong -- they might be too expensive, for example -- so back the drawing goes for revision. With a CAD drawing program, the design engineer can select the correct bearings from the catalog and place them in the drawing simply. Doing it by hand requires either lots of erasing or redrawing the whole thing.
There are other kinds of CAD programs besides those that automate technical drawing. Among the most useful are those that do "simulation". Without such programs, the only way to see if a design works is to build it and test it. With a simulation program the design engineer can tell the computer predict how a proposed design would behave if it were built. For example, the complete design of a motor could be fed into a motor simulation program which would use the information in the design to calculate and show how the motor would work (or not work!) under various conditions of load. A simulation program is sort of like a specialized video game that allows the design engineer to "play" with proposed designs for a particular sort of product. A motor simulation program can show how fast a particular motor design would run as the load on it is increased, how much power it would use, and how hot it would get, for example. Simulation allows design engineers to try out many different design alternatives. In our example, the motor simulation program can allow the engineer to try out various designs find the "best" motor for the machine it will be used in without ever building one.
Once the design is finished, the action moves from CAD to CAM. CAM programs allow the manufacturing process itself to be automated -- often based on data that comes directly from the CAD design. A simple (but extremely useful) example is using the CAD design to produce a list of all the things that are required to build the design. Such a list is called a "bill of materials". For example, the bill of materials for our motor would specify how much and what kind of wire is needed for the windings, what kind and how many bearings are needed, what kind and how much steel rod stock is needed for the motor shaft, and so on. Bills of materials are fed into many "downstream" CAM systems. Among them are those that purchasing managers use to buy the materials used in the manufacturing process and the systems that control how many of which sorts of parts are made.
Bill of Materials systems are important, but other CAM programs can do even more interesting things with the CAD design information. For example, the design of the shaft of our motor is completely specified in the CAD drawings. Without CAM, the drawing would be printed out and given to a machinist who would use a milling machine to turn steel rod "stock" into finished shafts. With CAM, the CAD design information can be fed directly into an automated milling machine which, with very little attention from a person, can turn out shafts one after another.
Actually, this example oversimplifies things quite a lot -- especially the case in which CAM is not used. Without CAM, if a lot of shafts are to be made, machinists would typically begin by making special "jigs" that assist them (by guiding cutting tools, for instance) to rapidly turn out many copies of the same shaft design. The jigs themselves need to be designed, built, and tested to ensure they work as expected. With an automated milling machine, all of these steps can be avoided.
Even though it is pretty long, this discussion of how CAD and CAM can be used to design and manufacture electrical components, it only scratches the surface. There are many other important and fascinating aspects we could talk about, for example how CAD/CAM can be used to design the layouts and workflow for manufacturing lines to build specific components, or how they can be used to help automate the testing of the things a factory produces. I hope it is enough to get you started in understanding this interesting area.
Try the links in the MadSci Library for more information on Engineering.