EDM Machine Size is Paramount

One issue that many machinists face is having a part that is bigger than the cutting envelope, which Extreme Wire EDM Services Inc. experienced with increasing frequency before its CUT P 1250 purchase. “It’s an ongoing problem because no matter how big a machine we buy, there’s always a larger job coming in. In some cases, we could only fit half of the block or part into the envelope. We would cut that end of it and then take it out and re-set it up for the other half to be cut, which eats up time and leaves a lot of room for mistakes and other hiccups,” Brian Bernt of Extreme Wire EDM Services says. Setups can take half an hour or a full hour each, depending on the difficulty of the project. If a job needs to run overnight, only part of the workpiece can be cut, which leaves the balance sitting there until morning. The constant need for larger, more efficient machining capability pushed Extreme to approach GF Machining for a larger wire EDM solution.

“We began talking with our GF Machining representative about designing a machine that would give us the ability to take on much larger work. It took a few years of research and development before a large AgieCharmilles wire EDM machine was available that had the features we wanted and needed, like the ability to cut tapers to the full height of the machine, a hardened table and collision protection as standard,” he says.

“Before we took delivery of the CUT P 1250, we had to turn away anything taller than 20 inches and anything longer than 43 inches. This is because the upper head on our next-largest wire EDM machine, an AgieCharmilles FI 640 CC, wouldn’t go any higher than 20 inches, and its doors are only 43 inches wide,” Bernt says. Sometimes, big workpieces were loaded into a machine with a forklift, which required setting the workpiece on rails above the table. “It wasn’t much of a solution, though, because we were losing Z height from having to raise the part up onto the rails,” he says. For example, if the rails are 5 inches high, the machinist could only fit a part that is 15 inches tall into the machine.

Raising the workpiece off the table also reduces the EDM machine’s flushing system efficacy. As the wire cuts, the upper and lower heads direct high-pressure water along the cutting wire to keep cutting paths clear of the micro-sized steel particles. Raising the workpiece off the table reduces the ability to flush particles, causing the machine to compensate by decreasing its cutting speed. This, in turn, increases the cutting time and may also compromise cutting accuracy as a result.

Conversely, the CUT P 1250 has doors that lower all the way around the front and sides, which allows Extreme’s machinists to load up workpieces as large as 90.551 x 51.181 x 29.528 inches from virtually any angle. “We can now set parts up to 90 inches in X and 54 inches in Y right on the table,” Bernt says. Even better, flushing is no longer an issue because the heads remain close to the workpiece. Plus, the increased capacity that the CUT P 1250 offers saves time and increases opportunities for Extreme. “It is hard to measure benefits to things like time and money because we’ve never had this kind of capacity in the past. Still, I will say that not having to do multiple setups or deal with rails and forklifts saves a lot of time.”

Extreme also has customers who need wire EDM services for large steel cylinders typical of the food and oil industries. “Before we had the CUT P 1250, customers would give us the large cylinders cut in half so we could do the work, and then they would dowel the cylinders back together. Now they don’t have to do that. With the capacity of the CUT P 1250, we’ve cut a 28-inch-long keyway into a cylinder with no need for additional steps. We have also cut slots on the inside of a steel tube for a massive drill or auger,” Bernt says.