CAD Input For EDM

EDM has a history of being "ahead of the curve" in adopting innovative concepts in metalworking technology. For example, EDM fielded some of the first applications of adaptive control, unattended operation and robotic automation. The Q3vic 3D Solution from Sodick (Schaumburg, Illinois) may represent another chapter in this ongoing saga.

This software runs on the wire and ram (die sinking) versions of the company's "LQ" Windows XP-based control unit. The software provides a special interface that allows the user to input 3D solid model geometry directly from the CAD system to use as input to the EDM control unit. Using CAD data as direct machine tool input has long been a dream that developers of other types of machine tools are now closing in on.

According to the company, 3D CAD data is analyzed by the software and automatically converted into machine commands based on parameters selected by the user. There is no separate step for creating an NC program in CAM software.

On the company's AQ L series of ram machines, the LQ control uses the CAD data to calculate not only the machine's axis movements but also those parameters for the electrical current and spark gap. For example, because the control interprets the actual CAD data, not an approximate shape, it can calculate the precise cutting area of the electrode engaged in the workpiece for finer, more accurate generation of sparks.

The result, the company says, is higher metal removal rates and a finer surface finish (as fine as 0.5 Ra) regardless of electrode size. Wear on the electrode is also reduced, making it unnecessary to produce additional electrodes in some cases. Setup is reduced, too. Using the menu-based dialogue, the user enters specifications regarding the workpiece material, desired surface quality, position of the workpiece and clamps, and any electrode changes that may be necessary.

On wire machines, the software interprets the CAD data and automatically develops a process plan that optimizes the settings corresponding to varying workpiece thickness, nozzle position and corner definition. The CAD data is used in conjunction with the company's new LQ33W high speed generator and linear motor technology on the company's AQ325L and AQ3535L wire models. The ability of the linear motors and the generator to respond to workpiece geometry allows sharply higher electrical current peaks and pulse modulation for more efficient cutting action, the company says.

One of the results, according to Sodick, is that plain brass wire that is 0.01 inch in diameter cuts as fast as more expensive premium-coated wires. An 11-pound spool of brass wire costs approximately $30, whereas the same spool of coated wire is about $132. Using coated wire can increase hourly consumption cost to four times that of using plain brass, making coated wire cost-prohibitive in most cases, the company says. Now this extra speed can be attained without the added cost.

To create the CAD data for the Q3vic software, the user must extract the 3D geometry of the electrode and related workpiece shape for sinker applications. For wire applications, the CAD data must represent the 3D geometry of the opening to be cut. In either case, CAD data must be exported in the Parasolids format for downloading to the control unit.