
Mechanical
Engineering - March 2007
Fine-Tuning
It In our age of MEMS. microsurgery, nanotechnology, and
general pursuit of minute mechanical marvels, even the smallest
vibration can become a big nuisance. For instance, people
in quality control actually have to examine the microchips
and tiny accelerometers that factories turn out.
Aiming to get a bigger piece of the action, the marketer
of a passive vibration-canceling system has struck a deal
with a manufacturer of isolation workstations to offer a product
that will combine both companies' abilities.
Low profile:
Minus K publishes a graph that compares the low-frequency,
vibration-canceling curve of its half-hertz negative-stiffness
isolator with the profile of a pneumatic system tuned
to about 2.5 Hz.
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Minus K Technology Inc. in Inglewood. Calif., has a passive
system that isolates equipment from low-frequency vibration.
It is collaborating with a maker of vibration-canceling workstations,
Kinetic Systems Inc. in Boston. Their products are used in laboratories
and by manufacturers.
Kinetic Systems has been making electronic and pneumatic
vibration isolation workstations since the 1970s, according
to senior sales engineer Larry Shaver. The new workstation,
designated MK26, is the company's first to use the system
from Minus K.

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Kinetic Systems has been making electronic and pneumatic
vibration isolation workstations since the 1970s, according
to senior sales engineer Larry Shaver. The new workstation,
designated MK26. is the company's first to use the system
from Minus K.
David Platus, president of Minus K, said his company
has been selling its vibration-canceling system to manufacturers
of other devices, such as atomic force microscopes,
and has been offering it in a workstation for some time.
Platus pointed out that this will be the first time
the company has marketed its negative-stiffness isolator
as part of a general-purpose workstation with a choice
of either honeycomb or other tabletop and the variety
of options that are available for the MK26.
As Minus K describes it, its vibration damping system
uses a spring that supports a load in concert with a
negative-stiffness mechanism to cancel vertical vibration.
Beam columns combined in series cancel horizontal vibration.
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| Steady work: The
MK26 workstation, a joint product from two vibration-isolation
companies, is designed to cancel very low* frequency vibration-about
99 percent of a 5 Hz interference. |
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The natural frequency of the system is usually tuned to one-half
hertz. As a result of the low resonant frequency, the surface
of the workstation is isolated from 99 percent of a 5 Hz vibration
and from 99.7 percent of 10 Hz. A video on Minus K's home page
showcases a desktop product, called 25BM-4, which is tuned to
half a hertz. Two wine glasses are on a table subject to a 5
Hz vibration with an amplitude of about a millimeter, the company
says. One, almost still, is isolated; the other, almost spilling,
is not. There are also a couple of coins balanced on edge on
the vibration isolation platform.
The Web site also has a "Technology" section that
explains how the company's isolation systems work.
The MK26 workstation consists of a Kinetic Systems frame
with a tabletop resting on the Minus K vibration isolation
device. The product is sold by both companies.
The stations are available in two sizes-30x36 inches and
36x48 inches-and in a range of weight capacities up to 650
pounds. They can come with options, including enclosures,
guardrails, monitor stands, and Faraday cages to block electromagnetic
interference, which will raise the price. The basic workstation
starts around $7.000.
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