Towards a step-NC compliant model for representation of machine tools

Universal definition of the machine tool is one of the critical factors to realise a universal manufacturing platform for CAx system integration including CNC machine tools. This paper presents the methodology to model the functional aspect of the machine tool without a hierarchical organisation of the machine tool by its purpose (turning, milling, grinding) and type (horizontal, vertical, multispindle). The main objective of this resource representation approach is to establish a universal procedure for representing available machine tool resources. This information can then be mapped onto the product model to derive machine specific process plans. The current information models of STEP-NC namely ISO 14649 can describe machining operations, technologies, cutting tools and product geometries. However, they do not support the representation of machine tools. The proposed model is intended to fill this gap by providing machine specific data in the form of an EXPRESS schema. Future issues are addressed in the paper to consider other auxiliary devices attached to the machine tool such as pallets and tool changers.