This is not a topic of many technical notes or blogs about accelerometers or vibration measurement, but it is one that comes up in discussion with users surprisingly often and has significant financial and practical implications.
Most accelerometer manufacturers today use laser marking or laser engraving to add part numbers, logo’s and the all-important serial number to their accelerometers. This is a quick process and one that can be used to create quite complex designs and images on hard metal such as Titanium, this all sounds very modern and positive…..BUT and it’s a big BUT, laser marking or engraving can wear off!!
Accelerometers can be used in harsh environments and they have to withstand uncompromising handling in addition to variable mounting methods including the use of adhesives, (which is often applied to the faces of the accelerometer that are not meant to be used for mounting). The result is, the faces of the accelerometer are rubbed clean, as adhesive is removed and with it goes the engraving, the accelerometer identification and traceability.
As a manufacturer of accelerometers, it is a comment we hear from customers a lot….’we had to stop using ???’s accelerometer because the serial number wore off’.
So What! I hear you say…, well, the history and traceability of an accelerometer is reliant on its serial number. At DJB we can provide the sensitivity of every accelerometer manufactured since the company started in 1974, that’s 45 years of records and its all done via its serial number. Calibration records rely on a serial number, specification and build records rely on a serial number, if you lose it the accelerometer is almost scrap.
So, what’s the solution?
Well it’s a little bit ‘old school’ but at DJB we still mechanically engrave our accelerometers, this means the serial number and other information is deeply cut into the metal of the accelerometer body and can never wear off. It is more time consuming but when you think about it, it is how it should be done.
The pictures above include accelerometers that have suffered years of use in harsh environment testing, they are covered in dents, damage and scratches, but are in full working order AND more importantly all their serial numbers are visible regardless of where they are on the accelerometer body.