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Computer-aided manufacturing (CAM) refers to the software 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.

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 (DNC) 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 generate an effective tool path.

Until the mid-1980s most software was limited to single-surface machining over one surface representation at a time. But since then, most software now performs multi-surface machining because the massive expansion of memory and computer power now makes it possible to hold an entire CAD model in triangulated form at the necessary level of tolerance.

Most machining progresses through three stages, each of which is implemented by a variety of basic and sophisticated strategies, depending on the material and the software available. The stages are:

Roughing

This process begins with a cuboid block of stock or a billet, and cuts it very roughly to shape of the final model. Often the result gives the appearance of terraces, because the strategy has taken advantage of the ability to cut the model horizontally. Common strategies are zig-zag clearing, offset clearing, plunge roughing, rest-roughing.

Semi-finishing

This process begins with a roughed part that unevenly approximates the model and cuts to within a fixed offset distance from the model. Common strategies are raster passes, waterline passes, constant step-over passes.

Finishing

In many ways similar to semi-finishing, but different in terms of what it starts from. After semi-finishing, the excess material is left at a constant thickness over the final surface, so during this process there is little change in metal removal rate, allowing the results to be accurate. (Like wall plastering, where the final layer is done against an almost smooth base.) Common strategies, in addition to those in semi-finishing, are pencil milling, rest machining.

All machining algorithms rely on finding valid cutter locations of the milling cutter against the model.

Because relatively specialized market, and the cost of the machine tools that it is designed to operate, CAM systems have tended to be very expensive, often in excess of £10,000 GBP ($18,000 USD).

Areas of usage

• In mechanical engineering
• In electronic design automation, CAM tools prepare printed circuit board (PCB) and integrated circuit design data for manufacturing.

See also

• CIM (Computer Integrated Manufacturing)
• DNC (Direct Numerical Control)
• FMS Flexible Manufacturing System
• ICAM Integrated Computer-Aided Manufacturing
• MPM Manufacturing Process Management
• Category:Computer-aided manufacturing software
• List of CAD companies
• List of CAM companies

External links

• CAD/CAM Overview Online Tutorial– from Tooling University, you can register and take this class for free.
• What is a CAM system?– By Mike Lynch
• What are the differences between manual, conversational, and CAM system programming?
• Open Source CNC Milling - GNU Computer Aided Manufacturing (GCAM)

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