CAD, CAM, or CAD/CAM? Is it for your shop? Focusing on only the machine-side of our industry, we get only a segment of a bigger picture. To enhance productivity we need to investigate all machining-related processes.
While we almost always utter "CAD" and "CAM" in the same breath, they're actually two separate, but interrelated software technologies that perform distinctly different functions essential in machining a finished part.
CAD software is a design tool used by engineers and designers to generate 3-D drawings and solid models on their PCs. It is increasingly being considered as a component of CAM.
In its simplest form, CAD software replaces ink-and-pencil line drawings. It utilizes dimensional data, libraries of select geometric shapes, and archived user-generated profiles to develop 3-D/solid model drawings that can be accurately scaled and easily revised. Critical dimensions, potential interference problems with mating parts, and esthetics can be visually verified, eliminating building 3-D models or machining pre-production parts, both costly operations. CAD drawings can be archived in resident PC memory or on other media and retrieved for future use including the design of families of parts.
CAM software is the process side of the CAD-CAM equation. CAM software translates CAD drawing data into a format it can manage and incorporates it with machining routines into a graphic part program.
The CAM programmer, like the CAD designer, has a library of software tools at his disposal. Here the library consists of detailed tool and process data. Typical archived tool information includes geometry, size, number of flutes (milling cutters), tool material, recommended speeds and feed rates, and tool life data. Standard process information consists of drilling, tapping, boring, reaming, milling, turning, and facing and can also include non-chip-making functions such as coolant regulation, clamping, and tool changing. The programmer can add his own shop's custom routines to the standard CAM-resident library, archive them and retrieve them for later use. Proven in-house processes can be applied as production standards used in creating part programs resulting in repeatable operations and profitably machined parts.
CAM software will handle tool and process parameters entered by the programmer and automatically generate tool paths and operational sequences. High-level CAM software will also automatically optimize speeds and feed rates and process progression, and will recognize and correct geometric programming errors.
CAM systems can generate animated graphics, some in real time that can be used to evaluate cycle times, tool paths, material removal rates, and other related functions that before could only be done at the machine tool.
Although CAM software programs are graphically based, they produce coded digital part programs that are converted by post-processors into CNC compatible part programs, capable of being downloaded to NC machine tools on the shop floor. The need for a post processor depends on whether or not the particular brand of CNC can directly process the as-generated CAM program code.
CAD and CAM software can be purchased either as separate modules or as integrated systems. Integrated CAD/CAM packages are gaining in popularity because they are cost competitive and provide all the benefits of CAD and CAM in one package without the concerns of compatibility.
The greatest benefit of CAD, CAM, and CAD/CAM programming software is time-savings, in some cases as much as 30%. Off-line programming, editing, and graphic model making don't interrupt machine tool production. Standard and user-generated data can be quickly accessed and inserted into the program. Using archived shop proven procedures assures consistent machining practices and simplifies cost and process analysis.
Part programs can be saved and retrieved for future use, either in their entirety or edited to develop new part programs, including families of parts.
Next time we'll examine what to look for when selecting CAD/CAM software, and additional features of CAD/CAM that can benefit your operation.
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|Title Annotation:||CAD/CAM COLUMN|
|Publication:||Modern Applications News|
|Date:||Apr 1, 2004|
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