January 2008 Edition

edm

Makino EDM webinar aims for aerospace manufacturers

 By Dennis Seeds

Jeff Kiszonas, EDM product line manager for Makino Inc., hopes the webinar he presents on Jan. 17 will enlighten some in the aerospace industry. He will discuss the results of new tests by Makino at a Nadcap-certified, independent laboratory: the new generation of EDM machines don't damage surfaces like they used to – and get parts made faster and cheaper.

"It's really just to open the eyes of some people in the aerospace industry to say, 'Hey, guys, you really need to reconsider your old specifications for this process. Look at what the new machines are capable of.' "

The presentation is part two of a webinar on the subject. The first part was given last July and is available online at www.makino.com. Kiszonas also hopes to present his findings at a Society of Manufacturing Engineers event in Toronto this May.

Several aerospace manufacturers, including Lockheed Martin Aeronautics, have recently performed extensive testing of parts made by EDM to determine if the process is effective and economical.

The general assessment among EMO exhibitors was very positive. More than two-thirds of them say they were more than satisfied with the run of the show. Exhibitors could reach all their key industrial target groups, especially automotive manufacturers and subcontractors, the mechanical-engineering industry, and the entire spectrum of metalworking and metal processing.

Makino went a step further to get more specific results. It tested 18 samples of three different aerospace alloys: Ti 6-4 titanium, 17-4 PH stainless steel, and 6061-T6 aluminum.

"What we found out, in the old days 30-40 years ago, EDM would leave anywhere from two to six thousands thickness of heat-affected zone [HAZ] that would contain micro-cracks, recast layer and annealed layer," Kiszonas notes.

"The EDM process today leaves no HAZ, and recast is down to less than .0004"," he says. "Micro-cracks are almost non-existent. Modern EDMs can produce parts with finishes down to 0.5micron Ry, tolerances in the submicron range, and leave the surface of any part with virtually no damage.

"The needs of manufacturing are driving EDM builders to develop machines that will maintain extreme accuracy while completing jobs faster. Useable wire diameters are down to 0.0008", Fine Hole drilling machines have produced clean, accurate holes of 22 micron diameter, and some builders offer customized machines for specific needs."

For the testing, conducted at IMP Test Labs of Lansing, NY, the samples were produced on Makino EDNC43S RAM EDM and SP43 Wire EDM machines using various electrode and wire materials.

However, the webinar will not focus on any particular machine, Kiszonas says. Lockheed's testing concluded that all major manufacturers' machines today obtain similar results. Makino's machines were slightly better – but only by a difference of millionths of an inch.

"So as a general statement, all EDM machines today of the major players do not damage the material surface like they used to," Kiszonas notes.

The improvements made over the generation of machines are largely due to the development and evolution of the generators.

"I cover this in both parts of the webinar. The older generators were DC generators. They had very limited adaptive control ability, if any. They were using a lot of the RC circuitry, whereas today's machines are using AC generators with highly adaptive gap control circuits to prevent damage to the parts. They're also using high-speed switching transistors to develop the spark instead of the old RC circuits. Those items all combined among other things, like anti-electrolysis circuitry and such, have taken us from that four to six thousands-thick damaged area to virtually no damaged area," Kiszonas says.

He anticipates a good turnout for the webinar. Whether the industry is receptive to the suggestions may be a matter of individual choice, he notes: "A lot of people are open to it, a lot aren't. The biggest resistance may be from the older engineers who are of the mindset, 'If it ain't broke, I'm not going to fix it' and also guys that just don't want to make a commitment to make a change that could affect people's lives. When you are talking about engines for an aircraft, or wings and fuselage components, or landing gear structure, guys say, "Hey, it's been working all these years. I'm not going to take the risk of changing and have a plane fail.' "

But on the other hand, some of the newer engineers who will be replacing those who retire see the need to make changes and they understand they need to re-evaluate some of these technologies, he adds. Makino Inc., www.rsleads.com/801tp-190

To register for the webinar, go to www.makino.com/about/shows_events/default.aspx

Dennis Seeds is senior editor of Tooling & Production magazine.

 

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