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Today's technology bolts onto yesterday's EDMs for quick, inexpensive machine maintenance.

Feb. 17, 2006
Mitsubishi Consumable Product Group's Van-TG Power-Feed Conversion kits ease wire-EDM maintenance and reduce the cost of consumables

Jeff Belyk of Bell-Key reaps the benefits of Mitsubishi Consumable Product Group's Van-TG Power-Feed Conversion kit.

Van-TG Power-Feed Conversion kits ease wire-EDM maintenance and reduce the cost of consumables.

Installed Van-TG Power-Feed Conversion kit on Keystone's 90-CS EDM.

Jeff Belyk dreaded having to change the carbide power-feed contacts on his old-model Mitsubishi wire EDM, and he wished the necessary maintenance job was as easy and fast to do as it was for his newer machine from the same builder. He got his wish.

Mitsubishi developed a conversion kit that can be used to switch the company's early AF-1-style power-feed systems, such as the one on Belyk's 110-HA wire EDM, to AF-2 and AF-3-compatible systems such as the one on the newer model machine Belyk has in his shop.

Belyk's Bell-Key Wire EDM Services Inc. is one of several shops that are taking advantage of conversion and upgrade kits that have allowed them to modify older wire-EDM equipment to make it more productive and profitable.

The conversion kit that Belyk used — the Van-TG Power-Feed Conversion kit from Mitsubishi — lets his shop run the same technologically advanced consumables, including carbide contacts, diamond guides and flush cups, of an AF-2 system on both of his Mitsubishi machines. AF-2 extended-life carbide contacts can provide up to 100 hours of burn time per index and can be indexed more times than AF-1 contacts, so shops such as Bell-Key consume fewer contacts. These contacts also change out faster and easier and without having to remove a machine's diamond wire guides.

On AF-1 systems, upper and lower heads house contacts within the heads' diamond wire-guide holders. This means the guides have to be removed to change contacts. Shops must re-align wire guides when they are removed and keep them aligned for close-tolerance work, but problems can occur if a shop is in the middle of a cut when contact maintenance is needed.

Re-aligning wire guides involves moving the wire to an open space on the machine's table to make it clear of workpieces, mounting a fixture, aligning the wire then re-locating the wire accurately to the correct part position.

According to Belyk, this re-aligning is time-consuming and not always possible. Also, it can be detrimental to part surface finishes because re-locating the wire exactly is a difficult job.

On the other hand, Belyk said he can change contacts on his AF-2 systems without disturbing the diamond wire guides or having to re-align the wire.

The AF-2 system provides small hinged doors that open with the turn of one screw on its upper and lower heads, and contacts mount in pocket areas separate from the diamond guides. "The biggest benefit of the new system for me is not having to practically disassemble an entire head to change contacts," Belyk says. That leads directly to greater productivity.

Shops could spend as much as 30 minutes to change contacts and to re-align wire on an AF-1-model power feed. They can replace the contacts in under a minute on an AF-2 or AF-3 system, says Brent Goff of Mitsubishi's Consumable Products Group.

Belyk says that he has to remove three screws to get inside the upper head and four to access the lower head on his AF-1 power feed. Once he gains access, he has to remove four additional screws that hold the upper diamond guide and three additional screws that hold the lower diamond guide.

"Taking all these screws in and out for routine maintenance was stripping their mating bolt-hole threads. It was getting to the point where we needed to either replace the heads and diamond holders or install helicoils to repair the stripped holes," he says.

As if having to remove a slew of screws was not enough, contacts for upper and lower heads were not interchangeable on Belyk's AF-1, and upper contacts could only be used once — they could not be indexed. The lower contacts could be indexed four times. AF-2 contacts are interchangeable between upper and lower heads and provide 24 indexes per head.

By indexing the Van-TG extended-life contacts 24 times each then switching the upper with the lower and indexing them another 24 times, Belyk says he can get a total of 48 indexes from each set of contacts. "After one year of use, I have yet to go through the set of contacts that came with the conversion kit," he notes.

Contact surface life depends on the power settings used, Mitsubishi says. Higher burn settings erode or wear contacts more quickly. While Mitsubishi says its Van-TG contacts can last 100 hours per index, Belyk says his shop is averaging 125 hours per index. "AF-2-style contacts may be more expensive, but their interchangeability and increased amount of indexing make them a better buy," he says. Belyk additionally points out that he saves money on diamond guides because AF-2-type guides are less expensive than the AF-1 guides.

While Mitsubishi offers installation, most shops install the Van-TG Power-Feed Conversion kits themselves in a few hours, Goff says, adding that all that has to be done for the old head is to be unbolted and replaced with a new head, reconnect hoses and do a square alignment.

Mike Miller, a journeyman tool and die maker at Keystone Friction Hinge Co. in South Williamsport, Pa., installed the kit himself and says step-by-step instructions supplied with the kit made it easy. Miller's shop put the kit on a used Mitsubishi 90-CS, which is about five years older than the Mitsubishi FX-20 wire EDM it also has.

"We knew what we were getting into maintenance-wise when we bought the 90-CS, so we did the conversion immediately. Now, maintenance is quick and easy and we save money using the same consumables on both machines," Miller says.

Before installing conversion kits, Mitsubishi recommends shops check to ensure that a machine's ceramic plates are in good condition and that the areas around the heads are clean.


Other EDM original equipment manufacturers also offer machine upgrades beyond those concerning consumables. Shops with early model Charmilles ( EDMs, for instance, can upgrade a machine's software, boost its power-supply output and add C-axis (die sinking) capabilities.

Software upgrade packages from Charmilles can provide shops with the latest advancements while correcting problems or glitches found in the early versions of software. The packages also upgrade machine interfaces, so shops can automate old Charmilles machines with robots or expanded toolchangers.

For those with Charmilles' Roboform 40/41 sinker EDMs made in the mid-1990s, software updates bring orbiting-cycle libraries up to par with today's machines. Such 15- to 20-year-old machines can now include Squar, Diag, Pyr, ISOG, ORB 3D, Squar 3D and ISOG 3D orbiting cycles. These machines also can benefit from restart and autorestart features on X, Y and Z axes and improved settings for polishing functions.

Shops can receive disks and perform software upgrades themselves. Besides orbiting cycles, the upgrades can include cutting parameters for today's popular materials, such as titanium, a material that older Charmilles machines do not have parameters for.

Charmilles EDMs are software-driven and have modular generator designs that let shops upgrade an old machine's power supply from 32 amps to 64 amps simply by changing a control board. The increased output can speed rough cutting, especially when running graphite electrodes with frontal surfaces that are equal to or larger than 1-in. square.

Along with power-supply packages, Charmilles' Performance upgrade package boosts positioning speeds, rib machining and pulsation rates from 15 mm (0.59 in.) per second to 30 mm (1.18 in.) per second. In addition, shops can switch the old tape drives on their machines to disk drives and can add flat-panel display screens.

A Charmilles C-axis upgrade package comes with a C-axis motor assembly, transmission shaft and spindle-base assembly and lets shops expand their machining capabilities for taking on a wider variety of jobs. Charmilles is able to offer such an upgrade because it manufactures its own C-axis units.

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