Developments in pre- and post-treatment of thin films and their influences on surface topography and coating adhesion strength of cutting tools

Abstract

Due to the increased requirements on machining of metallic and non-metallic materials, the pre- and post-treatment of hard thin films has been an important topic in several researches in the past decade. The main improvement in tool properties by a reduction of surface inhomogeneities is reached by an additional mechanical or chemical treatment before and/or after the coating process. Especially the cleaning before coating has to be considered to reduce the amount of debris of the pre-treatment which may negatively effect surface quality after the coating process. The mainly used processes of mechanical treatment to enhance surface topography before and after coating are several machining processes such as abrasive jet machining or drag finishing. This paper introduces a novel process for the pre- and post-treatment of coated cutting tools by elastically bonded diamond grinding wheels. Both the removal rate of surface inhomogeneities, the influence of surface topography before and after coating and the influence of the initial tool surfaces regarding coating adhesion strength were investigated to underline the potential of this pre- and post-treatment. Additionally, a new method for characterizing and describing the number of coating defects and proportion area of coating defects per $${\hbox {mm}}^{2}$$ is presented.