February 2012 / Volume 64 / Issue 2|
General-purpose tool shines on tough job
By CTE Staff
When two elements combine to create something greater than the sum of its parts, the result is typically a welcome surprise. Kline Oilfield Equipment Inc., also known as Kline Tools, was pleasantly surprised when it combined high-efficiency CAM software with a general-purpose endmill to machine 718 Inconel ball valves. The result was a 500 percent increase in tool life and an 86 percent reduction in cycle time.
Jake Aasness, who handles programming and technical applications for the Tulsa, Okla., manufacturer of in-ground, oil-well service tools, noted that Kline Tools uses the 2011 version of SolidCAM. The software includes the iMachining module, which optimizes cutting tool angles and feed rates through the entire toolpath to double or triple cutting speeds, according to developer SolidCAM Inc., Washington Crossing, Pa.
According to Aasness, the module’s algorithm generates a smooth, morphing spiral toolpath while controlling the cutting angle, feed rate and cutter velocity. “The tool, in theory, should always have the same chip load, no matter what,” he said, noting that the machining technique is vaguely similar to trochoidal milling. “I’m still impressed when I watch it. It’s like the tool is pulling itself through the material, and it doesn’t require any more load on the servos than it takes to move the table itself.”
However, the toolpaths the software generates do not enable every cutting tool to effectively cut difficult-to-machine materials. Kline Tools continued to experience problems when producing an order for 718 Inconel ball valves, which the company receives once or twice a year. “It was an absolute nightmare every time,” Aasness said, adding that the metal workhardens if machined dry and an endmill thermally microfractures if machined with flood coolant because the cutting edge repeatedly heats up as it engages the material and then cools down as it rotates around toward its next engagement.
Courtesy of IMCO Carbide Tool
According to Aasness, iMachining’s linear toolpath technology mitigates both situations by reducing cutting edge rubbing, thereby enabling increased rotational velocity. “As rotational velocity increases, both the amount of time the cutting edge is engaged and the time between engagements is decreased,” he said, “which further contributes to thermal stabilization of the cutter.”
The shop tried a couple of “fancy” high-performance endmills, hoping the advanced tool design and toolpath generator together would make a significant improvement, but the results were disappointing, according to Aasness. “The tools didn’t even make it through a second part.”
The Everyday Advantage general-purpose endmill from IMCO Carbide Tool Inc., Perrysburg, Ohio, is Kline Tools’ main endmill, with cutting Inconel being a previous exception primarily because the tool’s application guide doesn’t include speed and feed recommendations for Inconel. However, the shop had extinguished its supply of 3⁄8 " ones. “They were in dire need of finding a tool and a local distributor had the general-purpose IMCOs on the shelf,” said Chris Cooper, IMCO sales representative for Oklahoma and north and west Texas.
Once the familiar endmills arrived, Aasness test ran one in flood and through-spindle coolant at 4,074 rpm and a 50- to 60-ipm feed rate. He was not only able to machine two 718 Inconel ball valves without a hitch, but also cut 12 ball valves made of 4140 heat-treated steel, which has a hardness of 36 to 38 HRC. “I probably could have run 10 more,” Aasness said about the 4140 parts, which have a cycle time of 3 minutes. “The endmill still looked good once we were done.”
Now, Kline Tools gets five 718 Inconel parts per Everyday Advantage endmill, running at 6,000 rpm and 100 ipm. Cycle time dropped to 16 minutes from 2 hours. “That’s not even on the list for what the endmill is supposed to be able to do,” Aasness said.
“None of us truly thought the tool was going to work as well as it did,” Cooper said. “We were extremely surprised.”
Cooper attributes the tool’s success to its AlTiN (Spector) coating, carbide substrate and helix, clearance and relief angles. And he feels IMCO’s enDURO endmills, which were designed to cut challenging materials such as titanium and nickel-base alloys, would perform significantly better.
Aasness noted that he’d like to experiment with those tools, but the combination of price and performance for Everyday Advantage endmills is hard to beat. “They are very hardy endmills,” he said.
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