Hardness is a measure of the resistance of a material to be penetrated and eroded by
sharp projections of other materials such as diamond. The process of creating sharp
projections on any test surface is known as indentation. Hardness measurement of any
material is the result of a complex process of deformation during indentation. The
indenter tip geometry, which includes radius of curvature at the tip and tip angle,
affects the hardness measurement by influencing the nature of the penetration process on
the test surface, because every indenter deforms the specimen surface with a different
geometry. The controlled indenter geometry can improve the consistency of hardness
measurement. In this paper we report the estimation of two important geometrical
parameters, radius of curvature and tip angle of a Rockwell indenter by using a simple
method of image processing and compare the results with those obtained with a traceable 3D
optical profiler. Evaluation of uncertainty in measuremts is carried out as per ISO
guidelines (ISO-GUM) and a detailed uncertainty budget is presented. The tip angle
estimted is 119.95 degree. The radius of curvature is estimted to be 199.96 ± 0.80μm by image analysis which
agrees well with the value estimated by using optical profiler i.e. 199.12 μm.