Researcher studies the sound of rough

by Sheldon Smart
September 21, 2007

What is the sound of rough? That might seem like a question for armchair philosophers, but a McMaster engineering professor's answer has garnered him kudos and a substantial funding commitment from NSERC.

Philip Koshy, associate professor in the department of mechanical engineering, developed the idea of using sound to determine the roughness of a surface when he was driving on the highway and noticed that the road noise inside the car changed as the road's surface changed. Pairing this observation with research he had completed on pneumatic gauging led to his new invention: A Pneumatic In-Process Roughness Assessment System.

The system Koshy and collaborator Francois Yacoub have invented measures the roughness of a surface by directing a stream of air on the surface and listening to the frequency content of the back pressure using a sensitive industrial microphone. The signal is then mathematically correlated to the roughness value.

Surface roughness is a critical parameter in many applications, influencing friction, lubrication, reflectivity, corrosion and fatigue. Roughness is currently quantified using mechanical stylus or optical instruments that are well-suited for a laboratory setting, but are neither robust nor flexible enough for in-process application in a production line.

Philip Koshy

Philip Koshy, associate professor in the department of mechanical engineering


This project recently was awarded an NSERC Idea to Innovation (I2I) grant for $125,000. The grant will fund development of a prototype for an in-line, non-contact roughness sensor that would be suitable for rapid estimation of the roughness of a moving surface in a manufacturing environment.

"This I2I award is a huge vote of confidence in this technology," said Paul Grunthal, the McMaster industrial liaison officer who shepherded the I2I application to completion. He points out that the technology is enabling, and has a number of advantages such as easy integration into a machine tool and measurement of delicate surfaces.

The McMaster Industrial Liaison Office (MILO) has taken steps to patent the invention and has been working with a potential industrial partner to help commercialize the technology.