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EDM Machining Tips

John Moldenhauer is a National EDM Applications Engineering Manager at Methods Machine Tools. A 29-year veteran of the Sudbury, MA, based company, he has spent decades developing and deploying EDM solutions, and training operators and machinists on EDM platforms.

What are the most common applications for wire EDMs? Why?

Wire EDMs initially became popular in the 1960s among tool and die manufacturers. It has since expanded into a variety of industries, including automotive, aerospace and medical device fields. Wire EDM offers a level of accuracy that is especially crucial to the industries where extremely tight tolerances and the highest quality products are required.

What are the basics to know when getting started with wire EDMs?

Material must be conductive. For example, ceramics and plastics that are nonconductive cannot be cut on a wire EDM. However, FANUC produces, and Methods sells, the RoboCut Wire EDM series, which is the best machine for cutting materials like PCD, which is used for cutting tool tips. Polycrystalline composite diamond (PCD) is almost nonconductive, consisting of diamond in cobalt.

Part size can also factor into the limitations of an EDM. Standard FANUC wire EDMs offer up to 800 mm of travel on the X-axis, 600 mm on the Y and 500 mm on the Z. However, our custom work goes well beyond those limitations. For example, we are currently working on a custom EDM that has over 750 mm of Z travel.

What are some common challenges faced by EDM users? How do they overcome this?

On thicker workpieces, the wire diameter changes from when it goes in and starts discharging to when it comes out at the bottom. For many EDM users, this causes an unacceptable taper on the part. FANUC's Wire Straightness Compensation control feature automatically tapers the U and V axes (even when cutting in straight mode) to compensate for the change in wire diameter. This level of precision is needed in most industries that use wire EDMs.

What does Methods offer in terms of automation to support FANUC EDM? What are the advantages of adding automation?

Methods has developed automation for wire EDMs since the early 2000s, offering a wide range of solutions for EDM support and improving production efficiency for manufacturers.

One of the first large customer cells we created consisted of one robot feeding 12 machines on a 60' floor rail. That was in 2009. Since then, this customer has purchased four more automated EDM cells from us.

However, Methods offers more than just robotic part-handling arms and machine tending. For example, we created a turn-key automation solution for a customer that manufactures press brake dies. For this customer, we created a solution that intuitively enables the robot to not only select, load blanks and unload finished parts. The solution measures, loads, washes and dries the workpiece as well as the chucks that hold them-all without any manual intervention.

How has EDM technology changed over the years?

One example, FANUC came out with a new technology that does not use gap voltage. They are using feedback from the cut to determine whether each discharge (millions per second) removed material (successful discharge) or shorted out (did not remove material). When it shorts out, it corrects it immediately. The technology monitors a ratio of effective to noneffective to determine feedrate.

We do not program feedrate; the machine determines this as it goes. Wire breaks happen, but this new technology allows the machine to automatically adapt to those issues. When the wire breaks or gets cut, the machine can repair itself. It takes time for the machine to repair the wire. The fact that the machine executes the operations on its own saves time and energy for the machinist, as well as reduces time not spent in the cut.

What should machinists or operators know about EDM that maybe they were not aware of?

We often hear, "I do not have work for EDM." Chances are that is not true. EDM is more and more an attractive option for certain types of cutting, particularly if you are working with very hard materials like nickel alloys, and need to cut very intricate profiles or have the highest level of finish. EDM is likely the way to go. And, there is the added bonus of the very high reliability, which means EDM, at least our RoboCut series that can run with almost completely unattended.

Lastly, it is getting easier to operate today's EDM platforms. Wire EDMs are not your typical CNC machining center, and so it often creates hesitancy among machinists. However, the evolution of the technology and the increasing simplicity to operate an EDM machine makes them easier than ever to get started.

Authored by Methods Machine Tools

For more information contact:

Methods Machine Tools, Inc.

65 Union Avenue

Sudbury, MA 01776

877-MMT-4CNC (877-668-4262)


William Keim, General Manager

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Houston, TX 77041



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Methods Machine Tools, Inc.

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