TMS Square sensor & calibration tips                                                                                      Your one-stop sound & vibration shop
Dear Scott,

Welcome to our next issue -

The goal of this monthly communication is to provide technical information and tips about the calibration and use of dynamic sensors in vibration, pressure and force.  The information is provided by the PCB Group of companies, as well as industry experts from research, government and academia.  Technical information is presented in a short, easy to read format and will contain liberal links to further information should you desire a deeper dive into the technology.  

Tip of the Month

Tips for using adapters when calibrating...

Back-to-back reference accelerometers typically have a -28 or 10-32 mounting thread.  Sensors under test (SUT) often require a different thread interface.  In these cases, mechanical adapters must be used to allow for an appropriate mate. Unfortunately, adding this mechanical adapter also adds mass and reduces stiffness between the reference and SUT, which effectively reduces the mounted resonant frequency.  The result may be an out of tolerance condition in the upper frequency range, say 10 kHz.  The best practice is to avoid using adapters if possible.  As this may be unreasonable with certain SUT's, the next best practice is to use as small of an adapter as possible, with proper torque and ample silicone lubricant at each mating point.  Keep in mind that if you are having trouble comparing calibration data at higher frequencies with the OEM or another calibration laboratory, it is important to understand if both labs are using similar mounting conditions.  If not, this may be a substantial contributor to measurement uncertainty.
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Newsletter Archive
May 2007 - Basics of Accelerometer Function; How Standards Link Together
June 2007 - Shear, Compression, Flexure; ISO 16063 Overview
July 2007 - Accelerometer Transduction Types (PE, PR, VC); Laser Primary Calibration
Which is a better sensing element...
...Quartz or Ceramic? 

Balance ScaleOver the years there has been a great deal of discussion over the merits of selecting either quartz or ceramic as the sensing element for a piezoelectric accelerometer.  This month we'll review the benefits of each, along with citing the specific applications where either one or the other excels.... pun?

Click here to learn whether quartz or ceramic is best for your application.
Basics of ISO-16063-21...
...Accelerometer Calibration via Reference Standard 
Back to Back CalibrationISO 16063-21 describes the most common embodiment of laboratory accelerometer calibration.  Utilizing either a back-to-back (piggyback) reference standard or a specially constructed reference standard accelerometer imbedded inside a precision calibration exciter, this method provides the speed and simplicity of direct sensor under test (SUT) mounting and calibration.  Modern computer controlled calibration systems can provide calibrations and prints of calibration certificates in just a few minutes. 
Click here to learn more...
As always, your satisfaction is at the pinnacle of our work.  If you have questions that you would like answered, please contact us and we'll be glad to help out.  Your question may even be featured in a future month...
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Michael J. Lally

The Modal Shop

A PCB Group Company