A STEP-compliant computer numerical control based on real-time Ethernet for circuit boardmilling

Abstract

With the globalisation of manufacturing industry, extendable and networked computer numerical control systems that can support bidirectional and seamless data exchange are in urgent need. This paper presents a STEP-NC compliant controller based on Real-time Ethernet technologies, which consists of functional modules such as General Interpreter, Machining Manager, Tool Path Generation, Machine Tool Model, Simulation and Real-Time Ethernet Interface. The proposed controller is implemented for circuit board milling. In the controller, STEP-NC is utilised as the data format, as well as a part of the controller's software structure. The late binding together with object oriented polymorphism and iteration, which can accomplish general functions, is used in developing the interpreter. This, together with the Reflection mechanism, also realises the general function of creating and modifying some of the STEP data. This controller is then tested on a circuit board milling machine, with ISO 14649 files generated by a CAM module developed in association with this work, in which some AP210 entities are added to represent circuits’ geometry and translated to machining features in the STEP-NC format. Moreover, machining a single feature with multi tools is discussed and the concept of final features is adopted; all contribute to some effective milling strategies.