Prediction of coefficient of friction by using ring with triangular boss compression test

Abstract

ABSTRACT Ring compression test is a quantitative method used to evaluate various friction conditions at the interface of tool and work piece, by the analysis of inner diameter variations of the ring in metal forming. But the precise measurement of inner diameter of the ring is very difficult due to non-uniform deformation of the inner hole after the compression. To overcome these difficulties of measurement in conventional ring compression test, an alternative method named ring with triangular boss compression test (RTB-CT) is proposed in which two types of geometries of the ring were used one is ring with equilateral triangular boss and another is ring with isosceles triangular boss. Simulations were carried out for geometries of RTB-CT and results for different friction condition were obtained. The calibration curves for ring with equilateral triangular boss and ring with isosceles triangular boss were separately constructed for above mentioned friction conditions. Finally, this method was experimentally verified in determination of coefficient of friction of various lubricating conditions in the cold forging of aluminium rings. Results showed that the shapes of triangular boss remain same during deformation and the sharp edge of triangular boss makes the measurement of outer diameter is quite easier and precise.