EDM today and tomorrow Essay

Although the current scope of EDM ranges from small hole drillingto sinking 100,000-lb automotive dies, the advent of CNC verticalsystems and CNC wirecut systems has dramatically expanded both thenumber and sophistication of EDM applications. During the past five years, EDM sales, in units and dollars, havefollowed an upward trend. Unit sales are projected to increase at anannual rate of approximately 20 percent during the next several years,with the product mix swinging sharply to full CNC adaptive control. Basic systems will continue to be the mainstay of the small- tomedium-sized tool and die shop. In other areas, introduction oftraveling wire systems with adaptive control, auto wire rethread, andintial start-hole cutting units have pressured manufacturers of verticalEDM systems to provide the same untended operating capabilities for allEDM systems.

The next few year should see major emphasis onmicroprocessor power supplies, five- and six-axis CNC systems, automatictoolchangers, automatic electrode refeed devices, and in-process gaging. Systems innovation Increased cutting speeds and computerized controls on major EDMsystems are reducing cutting costs to the point that many largeautomotive and aerospace companies are purchasing EDM production systemsrather than individual units. This was reiterated last October at theNMTBA Fall Forecasting Conference where participants predicted that,within a year, the auto industry will no longer purchase stand-alonemachines. The emphasis will be on EDM systems used with DNC andflexible machining cells. If stand-alone units are purchased, they mustbe retrofitable to be used with DNC and FMS.

The aerospace industry is heading the same way, but at a slowerrate. Major aerospace companies are committed to untended, integratedFMS cells for their production systems. Direct postprocessors can nowlink EDM systems with CAD/CAM units, host computers, and FMS cells. Because productivity increases are essential, both automotive andaerospace industries will likely move toward integrated, dual-systemsFMS cells incorporating CNC traveling wire and vertical EDM units, withrobotized load/unload systems. In some case, CNC wirecut systems are interfaced directly withengineering for production of die shoes and trim dies. And, largevertical diesinking machines are being linked to CAD/CAM systems. Vertical EDM production systems are being equipped with orbitingtables to eliminate operator involvement during roughing, semifinishing,and finishing operations. Multichannel power supplies can now storepreprogrammed data on cutting conditions.

Overcut data (by material) canbe selected, entered into memory, and run automatically. Big market potential One of the largest vertical applications in the history of EDM maysoon develop as automakers swich to fuel injectors as standard equipmenton most cars. They have committed to placing such systems on 85 percentof the 1986 production models.

While the final method of producing fuelinjectors has yet to be defined, with auto productions estimated at5,073,214 units and only 8 percent now equipped with gas or dieselinjectors, the purchase of new EDM micro-hole production systems quicklycould reach $175 to $200 million. Present fuel injectors require 0.008″-to 0.010″-diamicro-holes in a specific pattern for fuel distribution.

EDM systems toproduce the injectors will require refeed heads for automatic electrodesetting, automatic handling systems, in-process gaging, automatic partcleaning, and CNC interface systems. The aerospace industry has used this system approach for years toproduce jet engine components. Micro-holes are EDMed on the leadingedges of turbine blades to provide cooling and aerodynamic stability.Testing on new generation jet engines shows that intricate shapes andprecision micro-holes will be required.

Complex geometries will consistof diameters, taper angles, and rectangles. Formed electrodes, set ingroups for simultaneous machining, will be used to cut these shapes. While present laser systems are not capable of producing thesecomplex geometries, they are able to remove material much faster thantoday’s EDM systems.

An integrated manufacturing cell,incorporating a laser for mass material removal and CNC electricaldischarage machining for finishing, may well be the best way to producethese parts. Also, direct CAD/CAM links, in-process gaging, andautomatic load/unload systems will play a major role in aerospace partproduction. Wirecut EDM systems have moved from the lab to the production floorin many aerospace plants. Wirecutting turbine-blade root sections andEDM blade contouring should go into production at a number of aerospacefacilities early this year. T;D still big Beyond the automotive and aerospace industries, EDM systems arewidely used in tool and die production and various other manufacturingenvironments. A breakdown of the current individual market share for anumber of industries is presented in Figure 1.

CNC vertical (ram) EDM machine sales should grow at 40 to 60percent annually for the next few years and taper off to 35 percent peryear thereafter. This growth will be partially at the expense ofconventional (non-CNC) EDM. The number of traveling wire CNC machines sold will grow at therate of 20 to 30 percent. Most of this will come from precisionapplications in aerospace, and jobs such as punch and die sets,extrusion dies, and form tools. For more information on EDM equipment, circle E70.

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