A robust scratch tester for industrial application has been developed to evaluate PVD TiN coatings on M2 tool steel by plots of the effective coefficient of friction for indenter movement, mu(eff) = F-H/F-V, as a function of the vertical force applied to a Rockwell C diamond indenter. A clear transition between different slopes in such a graph is correlated with the critical load for coating failure as identified by microscopic observations. The variation in mu(eff) as a function of vertical load is explained initially by the work hardening of the surface region due to contact with the indenter. As the applied load is further increased, the ploughing force within the coating and the shearing force due to adhesion between the coating and the substrate begin to dominate the behaviour of mu(eff). Results for coatings on different substrates are presented to demonstrate the versatility of the unit for industrial testing.