There isnt a single company OEM or supplierthat probably
isnt interested in doing things faster. The fact that product life cycles
are decreasing regardless of what the product is drives this need for speed.
To help accommodate this acceleration, equipment manufacturers have been working
to provide machinery that is fast. Exceedingly fast with regard to such things
as spindle speeds and axis movement.
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| The 03
Acura NSX: 290 hp @ 7,100 rpm; 224 lb-ft of torque @ 5,500
rpm, and a four-year/50,000-mile warranty. Thats performance
in all aspects of the word. |
That said, however, many of these equipment manufacturers, even those that
offer fast machines, provide a caution. They correctly argue that what needs
to be taken into account when making a decision about machinery and associated
equipment is throughput, not sheer velocity in one aspect or another. At the
end of the day (or shift or cycle or whatever it is that you use as a metric)
what really matters is how many machined parts youve produced, not how
quickly the machine was able to perform one aspect or another of its operations.
Still, just as we like to consider the performance of cars that go fast, so
to there is a fascination with machinery that operates at blistering rates.
Which brings to mind a story that was once told to me by the editor of one of
the automotive buff books. He was talking about the Acura NSX, the aluminum-bodied
sports car thats now equipped with 290-hp engine and is capable of getting
up in the 175 mph vicinity. And he said that of all of the sports cars in the
world, the only one that hed willingly drive through a desolate landscape
would be the NSX because he was confident of its fundamental reliability as
a machine. In other words, here was something that while unlike, say, an Accord
in most characteristics other than both being Hondas, was something that would
get the job done. So is the case with the machining centers weve collected
here*. Fast, yes. But useful, too.
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| Somehow, an
engineered drawing is suitable for a highly engineered performance
machining center from Heller. |
Heller Machine Tools (Troy, MI) has a lineup of horizontal machining centers
that includes the MC 16 (630 x 630 x 630-mm cube) and the MC 25 (800 x 800 x
800-mm cube). These machines can provide a spindle speed up to 24,000 rpm. The
spindle acceleration of 1 G brings the tool up to 8,000 rpm in 0.5 seconds.
Chip to chip time is 1.8 seconds for tools 6-in. in diameter or less. Changing
a loaded pallet can be accomplished in 9 seconds. All of which means that it
is about keeping the tool in the cut longer rather than waiting for things to
happen.
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| Mori Seiki engineers
took the approach of taking an already quick vertical machining
center and then figuring out how to make one thats even
faster. |
The NV5000 vertical machining center from Mori Seiki (Irving, TX) offers a
spindle with a maximum speed of 12,000 rpm. Whats important to note about
it is that, because it uses whats called DDSDirect Drive Spindlea
gearless mechanism, the machine is able to provide its full power22 kW
over 15 minutes; 18.5 kW, 30 minutes/continuousat all speeds, which helps
boost productivity. The spindle can go from 0 to 12,000 rpm in 0.97 seconds.
It decelerates from 12,000 rpm to 0 in 0.91 seconds. Chip-to-chip toolchange
can be accomplished in 3.1 seconds. The rapid traverse rate for all three axes
is 42 m/in; the X-axis gets up to rate at 0.43 G; Y-axis acceleration is 0.39
G; and Z-axis acceleration is 0.74 G. One of the things that Mori Seiki engineers
did was to benchmark their previous-generation vertical and then set about to
trump it.
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| Linear motors
help move the DMP 60 V linear to use those tools to remove
serious metal. |
The DMP 60 V linear vertical machining centers from Deckel Maho Seebach [Germany]
GmbH (DMG America) makes use of a linear drive on its X-axis so that it has
a rapid traverse rate of 80 m/min. The rapids in the Y- and Z-axes are both
65 m/min. Axes acceleration is performed at 1 G. The 25-kW integrated motor
spindle provides 18,000 rpm and a torque of 94.9 lb.-ft. So not only is there
speed, but also high material-removal capability. There is a clever toolchanger,
that has a modified double-gripper design, that synchronizes the turning and
lifting motions when in action so that there is a chip-to-chip time of just
1.8 seconds. Look for more linear motors on various machines from DMG. The company
is committed to using them where they make senselike on this machine.
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| Although Grob
will engineer the BZ 500L with ballscrews, the linear-motor
equipped version is speedier. |
Designed to make quick work of things like aluminum cylinder heads, the BZ
500L from Grob Systems (Bluffton, OH), a horizontal-spindle machining center
equipped with linear motors, provides an X, Y, Z-axis speed of 120 m/min. The
500-mm pallet machine accelerates to get there rather quickly, as well: 10 m/sec2
for the X- and Y-axes and 34 m/sec2 for the Z-axis. The top end for spindle
speed is 18,000 rpm. And the chip-to-chip toolchange is 3.1 seconds. Although
the machining center can be equipped with ballscrews, for those who are really
seeking speed, this is the way to go.
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| The a51 from
Makino is engineered with supplier requirements in mind. |
Designed particularly for suppliers, the a51 horizontal machining center from
Makino (Mason, OH) is a 400-mm pallet machine with a spindle that provides up
12,000 rpm. The a51 has a rapid traverse rate of 50 m/min and a cutting feedrate
of 40 m/min. The axes travels are 560 mm for X and Y and 500 mm for Z. The tool-to-tool
change time is a mere 0.9 seconds and the chip-to-chip time is 2.3 seconds.
The index table rotates at 47 rpm. Makino has engineered this machine and others
in its line to be not only affordable, but seriously capable.
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| TEquiping the
machining center with the "speed Package" means significantly
improving the rate things can get done. |
Although the HMC 95 (500 x 400-mm pallets) and HMC 135 (630 x 500-mm pallets)
horizontal machining centers from Giddings & Lewis (Fond du Lac, WI) are
specifically designed for high-production environments (e.g., theyre built
with a solid cast-iron design), there is a recognition of the importance of
doing things rather rapidly in those places, so theyve developed what
theyre simply calling the Speed Package for these two machines.
What this includes is a 16,000-rpm spindle thats driven by a 35-kW motor.
The drives have been pumped up such that the rapid traverse rate is 70 m/min.
for the X- and Z-axes, and 60 m/min. for Z. The acceleration: 1 G. The package
provides a chip-to-chip toolchange time of 2.7 seconds. For those looking for
extra performance, the Speed Package is a must.