Page 25 - MetalForming July 2011

The 50-percent increase in pressure allows the firm to process thicker mate- rial and increase cutting speed on thin work, while maintaining edge-and sur- face-quality tolerances.
“For example,” shares JC, “cutting 1-in,-thick GPO 3 (a fiberglass-rein- forced thermoset polyester material), at 60 KSI we can run at 7 in./min. and achieve the required very-fine surface finish. Increasing pressure to 90 KSI, we cut at 32 in./min.”
The Mitsubishi gantry-style cutting machine features linear-motor guides driven by brushless AC servo motors capable of rapid positioning speeds to 787 in./min., quite an upgrade from Twinco’s original belt-driven waterjet machine. Maximum workpiece size is 6 by 10 ft. Of Twinco’s diverse mix of workpiece materials, 75 percent of what it cuts on the waterjet machine is metallic, and half of that is stainless steel.
“We also run a lot of aluminum, as well as copper busbar parts,” says JC. “Our sweet spot is in the 1⁄4- to 1-in. thickness range, although we can cut stainless steel, aluminum and copper to 2 in. thick.”
KMT rates its 60-hp 90-KSI pump as capable of cutting 0.5-in. stainless at 18 in./min., 1-in. stainless at 7 in./min., and 2-in. stainless at 2.5 in./min. Max- imum cutting speed on aluminum alloys: 55 in./min. for 0.5-in. plate, 21 in./min. on 1-in. plate, and 8 in./min.
on 2-in. plate.
A key feature that drew
Twinco to the Mit- subishi machine, according to the
Schatzes, is its four-axis Intelligent Taper Control (ITC) feature. “We’re often expected to hold tolerances to ±0.001 to 0.002 in.,” says the elder Schatz, “and we rely on the machine’s ITC feature to
make that possible.”
According to Mitsubishi, ITC pro-
vides 360-deg. taper control by adding a 1- to 2-deg. mechanical tilt to the cutting head. This tilt compensates
for the waterjet widening as it exits the focus tube. The firm notes that this allows a wall-straightness toler- ance of ±0.001 in. per 1⁄2-in. of work- piece thickness.
iPhone Monitoring for Lights-Out Cutting
Since cutting of thicker work runs relatively slowly, and processing nest- ed, large plates can take as long as 24 hr., the Schatz’s are experimenting with running the machine unmanned, after hours. “We installed a webcam that allows us to view machine operation on our iPhones,” says JC Schatz. MF
This sampling of parts cut by Twinco on its waterjet machine displays the machine’s broad range of capabilities.
A) A copper-alloy train-signal part waterjet-blanked from 1⁄6-in. sheet and formed in a stamping press; and the set of tools (of prehardened 4140 tool steel) used to form the copper part, also fabricated via waterjet cut- ting.
B) Twinco typically machines this part—a column clamp for elevator structures—from a casting. However, in this case, the flange is longer than usual and the order quantity was only 50, so Twinco waterjet-cut the part from 2-in. hot-rolled steel, then machined the holes.
C) The red plate is 2-in.-thick GPO 3 fiberglass-reinforced polyester.
D) Twinco waterjet-cut 3⁄4-in.-thick aluminum plate to fabricate this wrench, used inhouse during testing of the train stops it manufactures.
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