New developments in industry as well as new materials set high requirements for machining processes. With conventional processes these innovative materials are very difficult to machine due to high sensitivity regarding mechanical and thermal stress or to specific material properties. Significant differences in material properties occur especially when machining compound or coated materials. To meet these specific requirements new machining technologies are necessary. Here abrasive water jets have become a most recent tool in mechanical machining. Due to its geometrical and material flexibility and its ability of cutting hard-to-machine materials this technology is spreading more and more for two- and three dimensional cutting applications. The cutting process of the abrasive water jet is a complex system with many interactions and influences between process parameters. Thorough control of the process is essential to achieve best results and to meet high quality standards. With new approaches in process control and process modelling which is described in this paper, both quality and reliability can be improved making this innovative technology capable of meeting specific requirements and the highest standards.