Dynamic Balancing School

Synopsis

This article presents and explains the simplest empirical, trial and error, do-it-yourself balancing method suitable for dynamic single or two plane balancing of rotating machinery. This method is suitable for (some) onsite/in-place or (most) job shop balancing. No mathematics is required or used.

All empirical balancing methods require some method of measuring the amount of unbalance in a rotor. Measurements may be taken of the displacement, velocity or acceleration of its vibration. A cell phone with a vibration application is the simplest1. It is assumed that there is no display of the location of the unbalance, that is, there is no strobe flash illuminating a location on the rotor.

The second part of this article is a detailed explanation of the process of setting up a balancing amplifier which has a strobe output to display the location of the unbalance, either the heavy or light side. The explanation is at the balancing technician level with no mathematics. Simple vector diagrams are used to explain what the operator will see during the setup process but are not used in the process itself. Phase angle shift in the amplifier and cross-effect of the unbalances in the rotor and how to correct for them are explained in detail. This process calibrates the amplifier to display the location of the unbalance. This speeds up the balancing job particularly for production applications.

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