Excerpts from a Machine Design article:
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 what?s 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 machine?s 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.
13 years ago