Constant-Velocity Milling

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    Excerpts from a Machine Design article:
===========================================================http://machinedesign.com/article/constant-velocity-milling-spits-out-prototypes-0407
Constant-Velocity Milling Spits Out Prototypes
April 7, 2009
In the prototyping of molds, shops typically either EDM or machine raw stock into the needed form. EDM works well, if slowly. EDMed parts also need secondary polishing.
New advancements in machining tell an entirely different story. A recent vertical-machining center (VMC) features whats called a constant-velocity (CV) controller which provides a novel approach to chip-removal theory. CV technology is said to halve cycle times for the highspeed milling of complex prismatic parts while producing parts that are finished when they come off the machine. Better yet, CV lets cutting tools such as small endmills withstand higher speeds and deeper cuts without breakage.
The CV capability provides a competitive edge according to W. L. Gore & Associates, Newark, Del. The firm purchased a CV4020 Revolution VMC from GBI Cincinnati in Ohio, to make prototype dies and molds for electronic products. The geometrically complex prototypes range in size from about 0.53 to23 in. The company machines them from materials including plastic, Teflon, nylon, aluminum, and steel.
The machines controller features a high-speed multiprocessor that handles eight interpolated axes at 50,000 block-a-sec program execution in contrast to the 5,000 block-a-sec of even high-end CNCs. Because the processor can readily deal with the high volumes of data that describe the cutting toolpath, the tool maintains a nearly constant speed over the workpiece. This eliminates the acceleration and deceleration of conventional machines moving through complex 3D contours, a big factor in eliminating machining inefficiencies. ===========================================================
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I believe Makino has had this type of technology for a few years now. Very little polishing required after CNC high performance milling- not high speed machining like it was once referred as. Shut-offs are machined for 1-1 fit - again very little hand fitting required. Their "slurry" type CNC EDM die sinkers also are capable of a damn near polished finish. I looked at those machines around the turn of the century(long time ago)<g> before the Chicago Mold industry uprooted to China.
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