Partnership aims to put a brake on squeals

Paul Boughton

Sensor Products LLC is recognised for providing pressure profiling tools and ancillary services to engineers and other professionals for their R&D, design, and testing processes. Recently, the company began a partnership with the prestigious University of Liverpool in the UK.

PhD candidate Abd Rahim AbuBakar and his advisor, Huajiang Ouyang, senior lecturer and member of the Dynamics and Control RG sector of the university’s Department of Engineering, needed a way to assess disc brake contact pressure distribution and squeal. The department, well-known for research in the area of automotive engineering, began searching for a quantitative testing method to validate their study. After extensive internet research and referrals from colleagues, AbuBakar and Ouyang were lead to Sensor Products to try Pressurex, a popular tactile pressure sensing film.

Because friction is the most significant cause of break pad wear, AbuBakar and Ouyang used the film to capture static pressure distribution and magnitude across the brake pad surface. By evaluating this friction, the researchers believe that better design can be achieved, subsequently resulting in longer brake pad life.

“Right now, no brake manufacturer can completely eliminate squeal,” said AbuBakar. “And because of the lack of quantified research on contact pressure distribution and brake squeal, we felt compelled to comprehensively study the contact pressure changes.” He added: “Pressurex was a crucial tool in our testing. We hope the information acquired from this research can prompt the improved quality of brake manufacturing in the future to ultimately extend brake pad life.”

Pressurex sensor film is an easy to employ non-destructive testing tool that quickly and accurately maps and measures pressure distribution and magnitude between any mating, contacting or impacting surfaces. Able to detect pressure from 2 to 43200psi or 0.14 to 3,037kg/cm2, Pressurex is suitable for assessing surface contact inconsistencies in gaskets, clamps, bolted joints, heat sealing elements, lamination presses, nip rolls, welding heads, clutch and brake assemblies, tire treads, connectors, heat sinks, as well as many other industrial and applications.

Pressurex comes in the form of a large, thin, clear Mylar sheet, physically similar in appearance to a sheet of paper. When placed between contacting surfaces, the film instantaneously and permanently changes colour. This colour change is directly correlated to the specific amount of pressure applied. Precise pressure magnitude in psi or kg/cm2 can easily be determined by comparing colour variations to a colour correlation chart, conceptually similar to interpreting Litmus paper.

Sensor Products LLC is able to customise Pressurex for any application by laser cutting the film for small or precision areas and provides encasement services allowing for use in environments where water, oil or other liquids might be present. 

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