EDM today and tomorrow Essay

Although the current scope of EDM ranges from small hole drilling
to sinking 100,000-lb automotive dies, the advent of CNC vertical
systems and CNC wirecut systems has dramatically expanded both the
number and sophistication of EDM applications.

During the past five years, EDM sales, in units and dollars, have
followed an upward trend. Unit sales are projected to increase at an
annual rate of approximately 20 percent during the next several years,
with the product mix swinging sharply to full CNC adaptive control.

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Basic systems will continue to be the mainstay of the small- to
medium-sized tool and die shop. In other areas, introduction of
traveling wire systems with adaptive control, auto wire rethread, and
intial start-hole cutting units have pressured manufacturers of vertical
EDM systems to provide the same untended operating capabilities for all
EDM systems. The next few year should see major emphasis on
microprocessor power supplies, five- and six-axis CNC systems, automatic
toolchangers, automatic electrode refeed devices, and in-process gaging.

Systems innovation

Increased cutting speeds and computerized controls on major EDM
systems are reducing cutting costs to the point that many large
automotive and aerospace companies are purchasing EDM production systems
rather than individual units. This was reiterated last October at the
NMTBA Fall Forecasting Conference where participants predicted that,
within a year, the auto industry will no longer purchase stand-alone
machines. The emphasis will be on EDM systems used with DNC and
flexible machining cells. If stand-alone units are purchased, they must
be retrofitable to be used with DNC and FMS.

The aerospace industry is heading the same way, but at a slower
rate. Major aerospace companies are committed to untended, integrated
FMS cells for their production systems. Direct postprocessors can now
link EDM systems with CAD/CAM units, host computers, and FMS cells.

Because productivity increases are essential, both automotive and
aerospace industries will likely move toward integrated, dual-systems
FMS cells incorporating CNC traveling wire and vertical EDM units, with
robotized load/unload systems.

In some case, CNC wirecut systems are interfaced directly with
engineering for production of die shoes and trim dies. And, large
vertical diesinking machines are being linked to CAD/CAM systems.

Vertical EDM production systems are being equipped with orbiting
tables to eliminate operator involvement during roughing, semifinishing,
and finishing operations. Multichannel power supplies can now store
preprogrammed data on cutting conditions. Overcut data (by material) can
be selected, entered into memory, and run automatically.

Big market potential

One of the largest vertical applications in the history of EDM may
soon develop as automakers swich to fuel injectors as standard equipment
on most cars. They have committed to placing such systems on 85 percent
of the 1986 production models. While the final method of producing fuel
injectors has yet to be defined, with auto productions estimated at
5,073,214 units and only 8 percent now equipped with gas or diesel
injectors, the purchase of new EDM micro-hole production systems quickly
could reach $175 to $200 million.

Present fuel injectors require 0.008″-to 0.010″-dia
micro-holes in a specific pattern for fuel distribution. EDM systems to
produce the injectors will require refeed heads for automatic electrode
setting, automatic handling systems, in-process gaging, automatic part
cleaning, and CNC interface systems.

The aerospace industry has used this system approach for years to
produce jet engine components. Micro-holes are EDMed on the leading
edges of turbine blades to provide cooling and aerodynamic stability.
Testing on new generation jet engines shows that intricate shapes and
precision micro-holes will be required. Complex geometries will consist
of diameters, taper angles, and rectangles. Formed electrodes, set in
groups for simultaneous machining, will be used to cut these shapes.

While present laser systems are not capable of producing these
complex geometries, they are able to remove material much faster than
today’s EDM systems. An integrated manufacturing cell,
incorporating a laser for mass material removal and CNC electrical
discharage machining for finishing, may well be the best way to produce
these parts. Also, direct CAD/CAM links, in-process gaging, and
automatic load/unload systems will play a major role in aerospace part

Wirecut EDM systems have moved from the lab to the production floor
in many aerospace plants. Wirecutting turbine-blade root sections and
EDM blade contouring should go into production at a number of aerospace
facilities early this year.

T;D still big

Beyond the automotive and aerospace industries, EDM systems are
widely used in tool and die production and various other manufacturing
environments. A breakdown of the current individual market share for a
number of industries is presented in Figure 1.

CNC vertical (ram) EDM machine sales should grow at 40 to 60
percent annually for the next few years and taper off to 35 percent per
year thereafter. This growth will be partially at the expense of
conventional (non-CNC) EDM.

The number of traveling wire CNC machines sold will grow at the
rate of 20 to 30 percent. Most of this will come from precision
applications 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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