Coordinate Measuring Machines (CMM's)

The measuring speed and accuracy of Coordinate Measuring Machines (CMM's) are improving every year. Newer CMM's are being designed and built to be shop floor "hardened" so they can function with repeatability right on the production floor. Vibration is one environmental factor which can compromise a CMM's accuracy and repeatability.

Ideally, if all components of a CMM, including the part to be measured, were to vibrate in unison at a specific frequency, amplitude, phase and orientation, no degradation in measured performance would result. To the CMM, this situation would represent the same condition as no vibration excitation whatsoever, since all parts of the CMM would be synchronized relative to one another. It is only when components begin to move out-of-phase with each other that accuracy problems occur.

Horizontal Arm CMM's

Without compromising accuracy, CMM manufacturers provide their users with the maximum levels of vibration which their machines are capable of withstanding. This allowable vibration criteria is an important factor when considering the users' CMM installation site choice(s).

Bridge-Type CMM's

The accurate determination of the vibration levels at the CMM installation site is as important as the allowable vibration limits.

A vibration site survey will provide the amplitudes of vibration and the frequencies at which they occur. This data is recorded, analyzed and then compared directly to the manufacturer's allowable floor vibration limits. This comparison of data enables the isolation system designer to make the correct isolator selection.

All decisions relative to the isolation system's performance characteristics are made based on the accuracy of the vibration data.

Gantry CMM's

The type of isolation system chosen is based on its isolation characteristics as compared to the measured floor vibration. The most commonly used isolators for CMM's include elastomeric (rubber) pads, or pneumatic isolators due to their low frequency isolation characteristics.

Elastomeric pads have natural frequencies in the range of 5-20 Hz where pneumatic isolators (0.5 Hz - 5 Hz) provide greater lower-frequency reduction.

Foundations or inertia masses are sometimes required in conjunction with the isolation system. Foundations are necessary for large gantry and some horizontal arm type CMM's due to the stiffness and support requirements of the machine bases. Inertia masses or foundations are also recommended on some applications to lower the machine/mass center of gravity, which minimizes "rocking" on the isolation system and increases system stability.

Fabreeka's® expertise includes the design of rigid concrete masses and structural steel forms to meet the dynamic deflection and rigidity specifications of CMM manufacturers. We provide complete, detailed structural analysis and design drawings and specifications for construction or fabrication.

Click to see project overviews/case histories for CMM's

• Fabreeka® Isolates Custom CMM at Advanced Manufacturing Installed on an Inertia Mass
• Brown & Sharpe PCR Isolated on Support Mass at Ford Frame Plant
• DEA Bravo Isolated on Foundation at Chrysler Stamping
• Large Leitz PMM Isolated on Support Foundation at Solar Turbines
• Wenzel LH87 CMM Isolated on Existing Machine Frame at Toshiba
• Custom Isolators and Frame Designed for Isolating Large Zeiss UMPC at The Trane Company

Please contact Fabreeka's® Engineering Department for assistance with your particular application.