Profiting From Orbiting EDM

Orbiting - or vectoring - EDM machines use one electrode to rough and finish a job, thus eliminating the need for separate roughing and finishing electrodes. The results are a significant timesavings with polishing and finishing because the cavity walls are maintained smooth and perpendicular to the part, as well as less money spent on electrode materials.

Features

Orbiting technology - which basically uses an orbiting head to orbit the electrode around its center point to the desired radial cavity - allows for easier, more precise part control. The cavity size can be adjusted independent of the electrode size. And, according to Mike Levanduski, EDM sales manager of Hardinge, Inc. (Elmira, NY) - manufacturer of Hansvedt EDM equipment - this technology allows you to do up to 95 percent of all CNC burns at a fraction of the cost of actually purchasing a CNC machine.

"The machine gives you the ability to perform a Z-axis burn, and orbit or vector out to the desired size," Levanduski explains. "A normal burn on a conventional manual Ram EDM requires you to know the precise overcut, have perfect flush and requires the use of multiple electrodes - generally one rougher and two finishers - and still does not guarantee to eliminate taper. The same burn done on an orbiting machine would use fewer electrodes - generally a rougher and a finisher.

"Orbiting (radial movement) or vectoring (angular movement) the electrode provides better flush conditions, eliminates taper on the cavity walls and lets you control the desired size," he continues. "During the EDM, material is being removed by the electrical discharge. The debris (molten chips and electrode particles) are traveling up the cavity walls - creating a secondary discharge that causes a taper effect, also known as bellmouth, as they leave the cavity. Once you reach the desired Z-depth, orbiting or vectoring movement allows you to remove the taper caused by this secondary discharge. The taper will be removed using the same settings used in roughing the cavity. Once the taper is removed, you orbit or vector out until the desired surface finish is achieved by stepping down your power settings." The orbiting or vectoring movement also creates a vacuum - pulling clean dielectric fluid into the gap and forcing the molten chips out, which provides a better finish. The orbiting and vectoring movement is programmable up to .200 inch in each axis U and V.

The 75 peak-amp M-Pulse power supply provides the user with a built-in reference library. This feature allows you to select settings based on your EDM criteria, surface finish, and electrode and workpiece material. "The edit mode allows you to change the setting on the fly while burning and save the modified settings to the program," Levanduski states. "You have the ability to create and save your own settings to the library to save time on future job setups."

Levanduski adds that the orbiting machines are suitable for just about every application. "Any time that you can move the electrode into orbit you are way ahead of the game," he elaborates. "To manufacture one electrode, it may take you several hours, whereas with the orbiter it takes about five seconds to edit your program, eliminating the need for a new electrode. That's what EDM is all about - we're always looking for a way to take the labor out of the process, which in turn saves you time and money."

The orbiting EDM machines are great for smaller job shops that don't have a big budget to purchase a CNC machine and want to compete with that higher-end work, Levanduski notes. "It's easier, you get a better product at the end - and the way you obtain that product is a lot quicker, costs you less money and takes less time," he states.

Applications

For Greg Adkins, president of Meadville, PA-based Adkins EDM - which provides EDM'ing services and core work for the automotive and electronics industries - the biggest advantage orbiting EDM technology offers is the ability to make electrodes one uniform size. "Normally, on a lot of Ram EDMs without orbiting heads, you would start with one electrode that would be much smaller for roughing, then go to a larger electrode for finishing since you don't have the ability to move around," Adkins explains. "With the orbiting heads you can make all of your electrodes one size, kind of a happy medium - four or five thousandths under - and run them all the same. You can orbit to your finish." The same goes for Ron Novel, president of Xcell Tool & Mold, Inc. (Erie, PA), which builds connector molds as well as molds for the medical and pharmaceutical industries. "You can make an electrode undersized - you don't have to get your numbers exactly right on, and if you orbit out you'll have a cleaner wall that will be straighter," he states. "It's just more efficient that way."

Efficiency also is key at Edinboro Molding (Edinboro, PA) - another builder of connector molds. "Besides needing to use less electrodes, there are increased flushing capabilities due to the increased space between the electrode and the workpiece," notes Jason McGowan, an EDM operator/toolmaker. "There also is more flexibility and convenience. If you happen to have electrodes from a previous job that might be smaller, you can always orbit out because you have the ability to orbit bigger. Also, just because the machine has an orbiter doesn't mean that you have to use it all of the time - you can still burn straight up and down when necessary. So, there are more options."

Adkins sees real timesavings in electrode manufacturing. "The vectoring machines orbit quickly and burn well in the U and V axes," he says. "Close tolerance work - as far as seal areas, etc. - are much easier orbited. You get a uniform wall because you have full contact instead of coming from the top down where you would get electrode wear. Corners also are much better orbited."

Edinboro Mold's McGowan emphasizes, "The quality is so much better than standard EDM'ing because when the debris and particles don't have a way to get out it tends to leave a rougher finish."

The consensus is that orbiting and vectoring EDM machines are a vast improvement from the conventional manual Ram EDMs. The advantages of orbiting and vectoring are significant - enabling you to control part size accuracies, reduce polishing and finishing times, and allow you to save time and money by using fewer electrodes.