Noise Reduction

Noise, structure-borne noise, and NVH (noise, vibration, and harshness) affect vehicle/aircraft performance and passenger comfort. Structure-borne noise can be caused by the frictional interaction of metal-to-metal contact parts such as gears and bearings. This structure-borne noise can translate into a louder cabin/cockpit for both automotive and aircraft applications. Additionally, for aircraft applications, this structure-noise can increase cockpit vibrations.

REM’s ISF® Technologies are able to reduce structure-borne noise caused by the friction between metal-to-metal contact parts. This reduction in noise is achieved by the unique characteristics of the surface that REM’s isotropic superfinishing surfaces generate. The ISF Surface has low surface roughness parameters (ex. Ra <4 μin) and a non-directional isotropic surface texture that changes the harmonic and can dampen the overall noise signature. Gearboxes with ISF Processed components have completed the ATP and endurance testing showing reductions in noise, vibration, and operating temperatures due to lower friction.[1]

Per a technical study conducted by Bell Textron Inc. on a Model 429 Helicopter, noise reduction of 10 dB was achieved at the transmission gear mesh frequencies and a 1 dB overall reduction in the cabin sound pressure level based on the application of the ISF Process. The results represent a significant effect on passenger comfort through a reduction in cabin noise.”[2]  Testing undertaken by The Ohio State University found that isotropic superfinishing resulted in vibration reductions of ~30% for helical gears.[3] 

REM’s ISF Technologies can be applied to very wide ranges of components types, sizes, and metals. These processing technologies are available via outsourced processing at a REM facility or as technology installations at a customer site. Contact us today to learn more or to start a project.


[1] Hansen, B., Salerno, M., Winkelmann, L., “Isotropic Superfinising of S-76C+ Main Transmission Gears,” AGMA 06FTM02, 2006

[2] Ehinger, R.T. and Kelamin, C.J., “Evaluation of Isotropic Superfinishing in a Bell Helicopter Model 427 Main Rotor Gearbox,” American Helicopter Society 63rd Annual Forum, Virginia Beach, VA, May 2007.

[3] Houser, Donald, Vaishya, Manish and Sorenson, Jim, “Vibro-Acoustic Effects of Friction in Gears: An Experimental Investigation, Society of Automotive Engineers, Inc., 2001.