In most situations, knowing the environmental details is not required. KSI Active Isolation Systems allow equipment to perform without issue in 99% of all vibration and ambient shock environments.
All Buildings Vibrate
The actions of humans, machinery, ventilation and heating systems, and road or rail traffic can cause many vibrations. Although these vibrations have little effect on occupants, equipment used in research, inspection, precision manufacturing, and quality control cannot tolerate them. The ambient vibration levels in buildings, laboratories, and clean rooms vary widely.
Figure 5.1. Typical Building Vibration and VIBRAPLANE Performance. Image Credit: Kinetic Systems, Inc.
Figure 5.1 demonstrates an average time sample of a building with a severe vibration environment. The vibration is a random frequency disturbance and a random amplitude. In this environment, sensitive electromechanical equipment can suffer from various issues like structural damage and excessive signal noise. Optical equipment will suffer from low-frequency jitter, high-frequency image blur, and line thickening. In the short term, the result is inconsistent and unreliable performance. Over the long term, the effects are excessive wear, maintenance, and fatigue failures.
Sensitive instruments and equipment must be protected from faulty operation or failure by significantly reducing this vibration. The use of a KSI Vibraplane Isolation system, either when installed or integrated into the equipment by OEM designers when vibration-sensitive components are installed.
Figure 6.1. Safe Operating Environments for Various Classes of Equipment. Image Credit: Kinetic Systems, Inc.
In Figure 6.1, a four-coordinate environmental vibration nomograph has been superimposed. The rising coordinates of the nomograph conveniently enable direct reading of rms vibration amplitude as a function of frequency in units deflection, in./ velocity, in./sec, or acceleration, G in multiples of gravity, g.
The conservative data represents subjective opinions regarding operational issues like signal noise or optical blurring. Structural damage or failure is not represented. Also, the data are rms 1/3 octave bandwidth (23%) filter analyses. Adjustments are required when comparing data with other measurement bandwidths.
KSI Takes the Guesswork Out of Vibration Control
KSI is a global leader in the application and development of advanced low-frequency vibration control systems that offer vibration-free working environments for sensitive equipment. Below is an overview of KSI’s experience with vibration control methods to help with selecting the appropriate and cost-effective vibration isolation for your application.
Please note: KSI has performed all required calculations, and with over 30 years of applied vibration control experience, provides the end-user point of installation pre-engineered, low frequency, all-purpose, vibration-free tables and platforms for tabletop and floor mounted equipment. For the OEM, KSI provides unit active air mounts in dimensions and capacities applicable to custom integration with internal system structures and components.
KSI Vibration Isolation Systems and Optical Tables will perform without issue unless the work environment is inordinately susceptible to dramatic vibration fluctuations.
How Much Vibration is Acceptable?
With a wide array of instrument designs and components, equipment vibration sensitivity is a subject of continued research. The query of “how much vibration is acceptable” is not an exact science. Equipment manufacturers usually aim toward specific performance tolerances in a benign or non-critical development laboratory environment. The end user must provide a “safe operating vibration environment” at the point of installation.
The available data is limited on how much vibration various equipment classes can withstand. Various surveys have been compiled for this data and are demonstrated in Figure 6.1 to show the proposed safe operational vibration levels for several sensitive instruments.
Each equipment line shows the envelope of acceptable rms vibration amplitude vs the frequency, which should not be exceeded. The “allowable” vibration envelopes in Figure 6.1 are the proposal of numerous engineering committees for standardization by the International Standards Organizations (ISO) to supplement existing standards.
Vibration Surveys
KSI engineers are knowledgeable about the latest vibration survey and measurement technologies, as well as data analysis methods. Utilizing advanced data acquisition systems, high sensitivity accelerometers, and laptop computers, they are able to accurately measure and analyze location-specific data specific.
The data is collected for horizontal and vertical vibrations over the required frequency range (typically between 0.5 and 200 Hz) and an average reflects the typical working condition vibration levels at your location. The time-based data is transformed into a frequency spectrum for deeper analysis, then compared with allowable vibration levels of your equipment, as dictated by the equipment’s manufacturer.
Real time integration of the data and FFT analysis offer amplitude and velocity spectrum of the vibration conditions. This data is subsequently converted, plotted onto graphs (log scale narrow bandwidth spectrum, modified to octave or third octave bands) and compiled into a full report with specific recommendations regarding whether vibration control is necessary, to what degree, and the best way to proceed with an efficient, cost-effective solution.
When Is Vibration Control Necessary?
- In new buildings or facilities, KSI recommends and offers on-site vibration surveys to examine the environment. The applicable equipment requires isolation if the results show vibration amplitudes at excessive frequencies.
- If new equipment is being installed in an existing facility, and the current equipment is performing successfully with vibration isolation, then isolation should be maintained and adapted for the new equipment. It is far more time and cost effective to maintain a successful practice versus experimenting with a new, unknown situation.
- If new equipment is being installed in an existing facility where no current equipment is isolated, you can maintain it without isolation. However, new equipment often has greater precision and can be more sensitive than older equipment. It is recommended to isolate in this situation as a fail-safe, particularly if time is a crucial factor for going online.
NOTE: Another option to the “Point of Installation” vibration control discussed above is “Point of Design” vibration control in which isolation is integrated into the device. Here, equipment designers should pay attention to stiffness, mass, and damping.
For ideal results, KSI recommends that mobile parts be lightweight, rigid and damped. Stationary parts can be heavy, rigid and damped. It is best to place sensitive elements on a rigid platform inside the equipment console for grouped isolation. KSI can assist by offering custom-fit vibration protection for sensitive components.
Vibration Control at “Point of Design”
For OEM applications, KSI builds unit active-air vibration isolators, like those in Figure 7.1, which are promptly integrated into equipment to protect trays and platforms that hold vibration-sensitive elements. This approach is cost-effective and space-saving, and vibration control is achieved by process equipment manufacturers.
In situations where the equipment design is fixed and it is not feasible to add an integrated internal isolation system, KSI can create a custom-designed external isolation platform or table that provides the vibration environment protection needed.
Figure 7.1. Typical VIBRAPLANE Unit Air Mounts for OEM and Custom Isolation Applications. Image Credit: Kinetic Systems, Inc.
Vibration Control at “Point of Installation”
For end users, KSI builds an entire line of active-air and passive-air mounts, tables and platforms, with load capacities from 200 lbs to 20,000 lbs per unit isolator. They can provide standard or custom-designed table and platform configurations for research applications involving specialized assemblies of inherently vibration-sensitive components, like probers, mask aligners, and microscopes.
Please note: KSI has performed all required calculations, and with over 30 years of applied vibration control experience, provides the end-user point of installation pre-engineered, low frequency, all-purpose, vibration-free tables and platforms for tabletop and floor-mounted equipment. For the OEM, KSI provides unit active air mounts in dimensions and capacities applicable to custom integration with internal system structures and components.
This information has been sourced, reviewed and adapted from materials provided by Kinetic Systems, Inc.
For more information on this source, please visit Kinetic Systems, Inc.