A STEP-NC compliant CAx system for wire-cutting EDM component manufacturing
thesisposted on 21.01.2011, 09:53 by Keng H. Ho
For the past 20 years, CNC manufacturing has been relying on the proprietary format of G& M codes to control the machining process despite the remarkable advances made in machining and control technologies. This low-level format is based on the vendor-specific ISO 6983 standard, which provides limited information to the CNC producing a primitive machining process language concentrating mainly on the cutting toolpath. Moreover, the ISO 6983 data interface offers little or no interoperability between the different CAD/CAM systems and CNC's, which is recognised as the key shortcoming of the current NC part programming process. In recent Years, a great deal of research effort has concentrated on the development of a new data model for the next generation of CNC's entitled ISO 14649 (STEP-NC). It has been strongly argued that STEP-NC has huge implications on the integration of CAD/CAPP/CAM (CAx) systems, giving the opportunity to realise interoperable CAD to CNC manufacturing. This is largely due to the STEP-NC data model offering a bi-directional data interface with a high-level description of both geometrical and manufacturing information, thus providing a revolution over the current state-of-the-art in CNC manufacturing. This research provides an investigation into the programming of wire-cutting electrical discharge machining (WEDM) machines using a high level process planning description based on the evolving STEP-NC standard. At present, part 13 of the standard has been dedicated to the non-conventional material removal process employing the use of a specialised thermal machining technique to machine parts with intricate shapesa nd of varying hardness. The major contribution of this research is the design of a STEP-NC compliant CAx system framework with product and manufacturing information models supporting the WEDM process chain from product design through to machining process planning and CNC manufacturing. The research shows that conventional NC part programming is CAD-centric and can only offer an interim solution of satisfying the need for the WEDM CNC machining applications. STEP-NC strives for total integration of CAx systems with CNC by focusing on the standardisation of the product and manufacturing information for WEDM CNC manufacturing through the application of ISO 10303 standard (STEP). The research builds on such benefits and potentials of exploring STEP-NC to provide the basis for making a major step forward in facilitating interoperable CNC manufacturing for the WEDM process.
- Mechanical, Electrical and Manufacturing Engineering