Investigation into the effects of walnut and hazelnut shell dust additives on wear and friction behavior in commercial vehicle brake pads

Brake pad components are usually classified into five different groups which include binders, abrasives, reinforcements, lubricants and fillers. These materials have many different functions such as increasing the frictional stability, wear resistance and strength and reducing the porosity and noise. When selecting the materials for brake pads, the cost of production and the impact of these materials on the environment must be taken into consideration. In this study, safe and environmentally friendly brake pads were produced using natural additives which included hazelnut shell dust, walnut shell dust, boron oxide, borax and wollastonite. The aim was to test different compositions in order to obtain the most ideal mixture. Tests for wear, friction, hardness, density, porosity, compression, shear, and thermal conductivity as well as microstructural analyses were performed in order to evaluate the performance of the brake pads. Pin-on-disk and Chase-type testers and a specially designed device were used for wear friction tests. The friction coefficient values obtained from the devices are between 0.30-0.55 µ for all samples. The Taguchi method L18 test sequence was applied to determine the ideal parameters for the specially designed device. It was concluded from the test results that the brake pads produced with alternative dust additives were in accordance with the standards. Regression analysis showed that the coefficient of friction and the rate of wear as estimated by the Taguchi method were at a 95% confidence interval.