With almost 50 years of experience and more than 1000 lines delivered in 20 countries all around the world, Samac is a company leader in designing and building special equipment to assemble and test a great variety of products, especially electric motors and actuators. The extensive experience collected with these goods has allowed Samac to become the partner of top global manufacturers in many fields, like automotive, medtech, home appliances, white goods and consumer goods.
Tests of electric motors for e-bikes
A beautiful example of this know-how is a line, designed in the recent past, for the assembly and testing of electric motors for e-bikes, a project that benefits of the experiences gathered in the automotive industry but, this time, applied to the consumer goods industry.
The importance of a NVH test
The most particular process that this equipment can manage is the Noise, Vibration and Harshness (NVH) test, a kind of analysis that measures the periodic oscillations of a mechanical system to identify any structural damage in the analysed piece.
At the beginning of the process an accelerometer with 3 axis (X, Y, Z) goes in contact with the piece (in our application the electric motor) and when it starts turning and the speed becomes constant, the test starts and the accelerometer begins to acquire the vibrations. At the end of the test 3 signals from the accelerometer and 1 from the tachymeter are transferred to the NVH Analysis Library, which gives back values that are collected and historicized in the SQL server and Json format.
Through Samac supervisor it is possible to:
- Know the overall and if the RMS parameter is within the tolerances the piece is declared OK;
- Divide the FFT into many individual frequency bands, to analyse each signal (x, y and z) according to the frequency domains, and measure the working point;
- Do the order tracking analysis, needed to identify how the vibration of an individual component contributes to the overall level and so locating and preventing product failure;
- Analyse the base modulation level checking two indicators in a selected band. The first is an expression of the basic level produced by the source, the second represents another level due both to the modulation and to the grade of the ideal source, whose contribution is connected with spectral/temporal variations. The overall level is the sum of the two ideal sources;
- Do the peak analysis, checking if there are more than n peaks with a value greater than a certain threshold.
