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Frequently Asked Questions

No. This may be necessary with other designs but TMC holes are based on a proprietary design and manufacturing method which ensures that screws can always be easily inserted and removed by hand with no need for tools except for a final tightening. Under our CleanTop product listing, take a look at "20 Reasons for Choosing TMC CleanTop Optical Tables"
Generally speaking, yes, we make custom versions of our isolators out of non-ferromagnetic materials including stainless steel and aluminum. Contact our Application Engineering team for help.
Yes but with a caveat. The stiffnesses of the isolators should vary by at least two orders of magnitude with the “lower” isolators being the stiffer of the two sets. So an active feedback type isolator with very stiff internal springs may have a set of soft, low frequency isolators stacked upon it to create a two-tier system in which the transfer functions of the two systems are additive. However, stacking two systems with similar resonant frequencies can lead to instability due to the mass sprung between the upper and lower springs. For examples, see LaserTable-Base and CleanBench Aktiv.
The sensitivity of ultra-sensitive instruments, experiments, and manufacturing processes tends to correlate with measured velocity of the floor motion which is highest at low frequencies, typically 1-30 Hz. Above 30 Hz, even relatively simple isolation systems attenuate vibration very effectively. And, above 30 Hz, vibration on an isolated surface will be dominated by acoustic coupled noise, vibration reaching the surface through cables/hoses/etc., and self-noise and resonances of the isolated equipment. Therefore, if problems above 30 Hz are identified, the focus turns to acoustic isolation and other mitigation techniques, not more floor vibration isolation. For more information see our acoustic enclosures
Typically, yes. The STACIS active feedback control loop consists of a sensor measuring floor vibration, a signal processor and piezoelectric actuators expanding and contracting proportionally to an applied voltage in response to this signal with equal and opposite force to cancel floor vibration in real time. The high force piezoelectric actuator working in the vertical direction requires the floor meet a minimal stiffness. While some floors do not meet this requirement, most do. TMC provides survey services to measure the floor stiffness if there is any doubt. Contact a TMC Applications Engineer or Service team member for more information.

All inertial active vibration isolation systems consist of a mechanical spring, an inertial sensor measuring vibration, and a feedback and/or feedforward control loop. Serial simply means that the active control loop is in series with the spring. Parallel type active systems are very effective at cancelling payload motion because the sensor is looking up at the payload – great for moving stage applications for example. The serial-type system, such as STACIS, employs a downward looking sensor to aggressively measure and cancel floor vibration. When combined with a stiff spring to greatly reduce the impact on the control loop from payload resonance or movement, such a serial type system is inherently more effective at protecting precision tools from floor vibration. Many tools, such as electron microscopes employ internal passive isolators. A Serial hard-mount active system such as STACI allows the tool’s internal isolators to be optimized for high frequency vibration coming from the frame, electronics and other flanking paths. This combination is ideal for cancelling both high and low frequency vibration.

No, not on its own. STACIS systems are often installed in earthquake zones, however, along with heavy duty travel restraint brackets to prevent excessive motion in the event of an earthquake. TMC can design and provide the restraint brackets, and when necessary, can hire 3rd party engineering firms to review and stamp the drawings

While many STACIS-type products, like SEM-Base VI, do have a limited range, or application specific load capacity, STACIS III does not. STACIS III is a modular system consisting of 3 to an unlimited number of isolators, or pods, and therefore is not limited, as a system, by load capacity. The highest capacity isolator pod is rated for 4500 lbs (2045kg) and it is common to have 6, 8, or 10 isolators in a system, but again there is no limit to the number of pods in one system. Learn more.

Yes. The critical element in STACIS, the piezoelectric device, often used in precision Nano positioning systems, expands and contracts proportionally to an applied voltage. STACIS uses the same device to cancel low frequency, low amplitude building vibration. While any STACIS-type system can be “driven” to induce low amplitude vibration, only STACIS III offers the user full shaker capability with a user-friendly interface. With STACIS, the standard controller and firmware is provided with basic shaker mode: shake in “open loop” (active vibration isolation disabled) using the internal signal from the DC-2020 controller, in one axis at a time, at a fixed frequency and amplitude. Commands are sent via the DC-2020 GUI.

STACIS III can also be operated in advanced shaker mode, using an external signal generator connected to the controller front panel BNC. This requires a factory modification to the controller. Contact a TMC Applications Engineer for an “Advanced Shaker System” Quote.

STACIS controllers generate 24-48W average power. At the isolators it is 12-40W per corner/isolator. Not all of this is converted to heat of course. The controller is cooled with dual rear-mounted fans, and the isolators are often installed inside enclosures without a problem. For more information see our STACIS III page and our Tool-Base page.

The high force piezoelectric actuator working in the vertical direction requires the floor meet a minimal stiffness. If the floor is too soft, the floor deflection could be too high in response to the piezo force, and the STACIS control loop could be temporarily saturated resulting in a brief disruption of isolation. While some floors do not meet this requirement, most do. For example, any concrete slab on grade and most 150mm thick concrete upper floor meet STACIS requirements. TMC provides survey services to measure the floor stiffness if there is any doubt. Contact a TMC Applications Engineer or Service team member for more information. 

STACIS based systems are powered by the TMC Digital Controller, DC-2020, provided with a standard 3-prong power cord which plugs directly into a standard 15amp 120V receptacle. The power supply in the controller has a universal input accepting 90-240V 50/60Hz connection via any grounded international power cord with a C13 socket to connect to the back of the STACIS controller. Unlike traditional passive and pneumatic vibration isolation, STACIS does not require an air supply, it is not a “floating” isolator and does not change height when it is powered on or off. PEPS and ElectroDamp are used with pneumatic isolators which do require 80 psi CDA (Clean dry air).