Study of feasibility of plastic gear to reduce noise in a gear pump

Generally, gear pumps are classified as noise producing machines. With a view of reducing overall radiated noise level from gear pumps, without affecting the mechanical efficiency, an experimental investigation was carried out. In this study the possibility of utilizing a plastic gear instead of the conventional one was exanimate. On the rig built up for this purpose, two different kinds of tests were made. The first part of the experiment was devoted to measurements related to mechanical performances and the radiated noise level from a conventional pump with a metal gear mesh, under different operating conditions. The second series of tests was carried out mainly to know the effect due to the replacement of the idler metal gear with the plastic one. This test also was performed under various operating conditions. Serious difficulties were encountered with the plastic gear testing. On several occasions the plastic gear was destroyed. The debris from the plastic gear gave considerable trouble in some elements of the hydraulic circuit. In the plastic gear case, significant flow was observed. The results of the performance test on the plastic gear seem to be disappointing. Even though the plastic gear has good damping vibrations, there is no significant reduction in the overall radiated noise level from the gear pump. At low speeds, the plastic gear gave a lower performance rate compared to the conventional gear pump. However, at higher speeds, the performances were nearly the same. Further, the plastic gear seems to be unable to withstand a high level of loading. This can cause damages in the plastic gears and reduce the life period.