Computer-aided manufacturing

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Computer-aided manufacturing (CAM) refers to software that is used to generate the instruction codes for a CNC machine in order for it to cut out a shape designed in a computer-aided design (CAD) system. This means that the person who is watching over the machines has his or her job simplified.

Sometimes the CAM software is integrated with the CAD system, but not always. Every piece of CAM software must first solve the problem of CAD data exchange where in the CAD system which is producing the data often stores it in its own proprietary format, much as is the case with Word processor software. Usually it is necessary to force the CAD operator to export the data in one of the common data formats, such as IGES or STL, which can be simpler since it does not need to be edited.

The output from the CAM software is usually a simple text file of G-code, sometimes many megabytes long, that is then transferred to a machine tool using a Direct Numerical Control program.

While it has long been the dream to make the CAM software that can run on its own, it generally requires a human operator with much knowledge and skill of machining to select the Milling cutters and define the necessary parameters and strategies that will to generate an effective tool path.

Until the mid-1980s most software was limited to single surface machining over a single Computer representation of surfaces [Computer representation of a surface] at a time. But since then, most software now performs multi-surface machining because the massive expansion of memory and computer power made it possible to hold an entire CAD model in triangulated form at one time to the necessary tolerance, and this allowed more powerful and general purpose algorithms to be used.

Most machining progresses through three stages: roughing, semi-finishing, and finishing. CAM software must therefore provide the necessary strategies for performing these stages.

roughing: Zig-zag clearing, Offset clearing, rest-roughing.

semi-finishing: Raster passes, waterline passes, constant step-over passes.

finishing: Pencil passes, rest machining.

An entire CAM system tends to be expensive; a computer system with software may cost in excess of £10 000 GBP ($18,000 USD).

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