In achieving an accurate vibration test, the results are greatly affected not only by the performance of the accelerometer, but also by the way it is installed. In this article, we will introduce the proper method of installing accelerometers.
▶ EMIC's accelerometersProper handling of accelerometer
If the accelerometer is not installed and fixed properly, it will not be possible to make accurate measurements due to the limitation of high range frequency measurement and dynamic range. When installing and fixing the accelerometer, it is necessary to firmly adhere the mounting surface (bottom surface) of the sensor to the mounting surface of the test object. There is an optimal installing method depending on the shape and conditions of the test object. Introducing the 3 main installing methods.
Screws, adhesion, insulation ... Select according to the conditions of the test object Optimal accelerometer installation method
Fixing with screws
Fixing and mounting with screws is ideal when the product itself has screw holes or when you want to measure vibrations around the product. Make the mounting surface flat so that there are no gaps or tilts on the surface, and tighten it firmly with fixing screws so that they adhere. If the mounting surface is not completely flat, applying silicone oil or grease to the surface to secure it may improve the high-frequency characteristics.▲Installation image by screw fixation
Suitable test object: Objects with already mountable screw holes. Or, it is possible to machine additional screw holes for mounting.
Fixing by adhesive
If it is not possible to drill holes or screws to fix it directly to the test object, we recommend bonding it with an adhesive. After cleaning the adhesive surface so that it is free of dirt, moisture, oil, etc., bond it with epoxy adhesive or cyanoacrylate (instantaneous) adhesive. Proper adhesive fixation can provide the same characteristics as fixation with screws. To prevent the accelerometer mounting surface and screw hole from being damaged by removal after bonding, use the optional cap nut adapter to bond. The cap nut adapter has a threaded hole on one side to screw the accelerometer, and the other is a flat surface for bonding to the test object. Further, the flat side can be additionally machined to fit for mounting.▲Accelerometer attached with adhesive
Soft adhesives are not recommended because they degrade the characteristics of the high range frequency. Also, please note that in temperatures beyond the operating range of the adhesive, the adhesive strength will be reduced and the characteristics may deteriorate significantly or the adhesive may peel off.
Suitable test object: Compact and lightweight objects with that holes cannot be drilled
Electrical insulation
If the potential of the test object differs from that of the measuring instrument, or if fixing the accelerometer directly causes ground loops that may result in noise contamination, etc., it is necessary to electrically insulate the accelerometer from the test object and install it. To electrically insulate and mount the accelerometer, use an insulating stud (optional) that is compatible with the accelerometer, or use insulated screws and washers. Insulation can also be achieved by bonding the joint surfaces via an insulator such as ceramic or epoxy.When directly fixing the accelerometer with adhesive, electrical insulation may not be perfect due to the thickness of the adhesive layer or the effect of ambient moisture. For mounting with insulation, use a dedicated insulation stud or bond it via an insulator. Electrical insulation is recommended because it provides the highest measurement accuracy.
▲Installation image with electrical insulation
Suitable test objects: Test products made of conductive materials
In addition, there are also fixing methods using wax and mounting methods using a magnet holder. Since the appropriate installation changes depending on the shape of the test object and the conditions (conductivity, etc.), we propose the optimum accelerometer depending on the test product.