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Computer-aided manufacturing

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Computer-aided manufacturing (CAM) is the use of a wide range of Product Lifecycle Management computer-based software tools that assist engineers, in the manufacture of product components. 3D models of components generated in CAD software are used to generate CNC code to drive numerical controled machine tools. This involves the engineer in selecting what type of tool, machining process and paths that are to be used.

Overview

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, that are supported by a wide variety of software. The output from the CAM software is usually a simple text file of G-code, sometimes many thousands of commands 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.

History

The first commercial applications of CAM were in large companies in the automotive and aerospace industries for example UNISURF in 1971 at Renault (Bezier) for car body design and tooling.

Machining process

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, pencil milling.
Finishing
In many ways similar to semi-finishing, but different in terms of what it starts from.

Software providers today

The largest CAM software companies (by revenue 2005) are UGS Corp and Dassault Systèmes, both with over 10% of the market; PTC, Hitachi Zosen and Delcam have over 5% each; while Planit, Tebis, Missler, CNC (Mastercam), ESPRIT and Sescoi between 2.5% and 5% each. The remaining 35% is accounted for by other niche suppliers like OneCNC.

Areas of usage

See also

Template:Metalworking - CNC, CAD, and CAM

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