STEP-NC for EDM in Switzerland: Why, What, How ? by Van Khai Nguyen - PowerPoint PPT Presentation

IMS STEP-Compliant Data Interface STEP-NC seminar WZL, Aachen for Numerical Controls STEP-NC for EDM in Switzerland: Why, What, How ? by Van Khai Nguyen The data model and beyond… by Ian Stroud February 12, 2003 eig

The Swiss group • The EDM model has been worked on by a consortium of industry and academic institutes in Switzerland: • AMT - Consulting • CADCAMation – Software house • Charmilles (AGIE) – Machine developers • I-tech, EIG – Research • STI-IPR-LICP, EPFL – Research • Wyss SA – Machine tool user eig

Project overview Current situation New interface Hole2 Step1 - predrilling - roughing % - drilling - finishing N05 G54 Hole1 N10 G00 Z10.000 N15 G91 G0 Z200 CAD/CAM CAD/CAM N20 T5 D1 WW N30 G90 M5 Pocket1 business N35 G00 X0.000 - plunge - roughing Bidirectional N40 G00 Z5.000 ISO 6983 - finishing level N45 M08 data flow description{ filename= N50 S3183.000 ‘ncfile.prg’; N55 M03 date=‘20-01-1999’; Post Processer STEP-NC N60 F1477.000 } const{placement1= Vendor axis2_placement_3d(..); } specific shop-floor program() { set_placement(setup); ISO 6983 level exec plan.hole1drill; • Low-level exec plan.pocket_plunge; information exec plan.pocket_roughing; NC controller NC controller • Simple movements and switching NC machine NC Machine instructions • High-level information • Vendorspecific • Object-oriented extensions description • Use of STEP geometries • Vendor-neutral eig

Why STEP- NC for EDM? � Three main objectives � Standardization of the data structure toward an integrated “digital” manufacturing company � (EDM is still a proprietary process, non-integrated to the shopfloor environment) � Optimization and security of the data flow � (EDM is still programmed through 2D data, and wire compensation is still approximated in 2D) � Intelligent on-line functions and performance improvements � (EDM is still difficult to use & to predict, & simulation is still poor) eig

What are the benefits for EDM & EDM ? � Extending the Engineering Data Management integration & the Electro Discharge Machining capabilities A. An International Standard for engineering data (geometry, topology, technology, …) and probably non-technical data (our vision) - a Product Lifecycle Management bus for product description - total interoperability “from art to part” - flexibility for customization (global market) - cost reduction ... B. Advanced functions for intelligent wire EDM CAM/SFP systems - breaking up the limits of EDM technology (e.g wire cutting complex of ruled surface, nano-grinding of cutter, surface interpolation, …) C. Feedback of NC modified programs eig

Wire EDM Process Chain S T EP-NC file ISO 14649 CAD system: SolidWorks CAM system: AlphaCAM Charmilles ROBOFIL 440 S T EP-NC interface eig

Information dissemination & user application deployment � Demonstration showroom set-up & user application deployment Installation and Implementation of a STEP-NC compliant Charmilles machine Robofil 390 and realization of practical benchmarking with two skilled end-users: Wyss SA & B&B microtechnologies SA in order to spread up the use of the STEP-NC technology and its advanced features. eig

Achievements and directions • The first project succeeded in creating the initial EDM standard. This is now in the process of being approved as an ISO standard • The second phase has the goal of exploiting the improved information level for intelligent manufacturing. The initial algorithms have been determined and some experiments performed. • Improved algorithms at the controller level provides more information for machine operators to understand the geometry of the piece in the context of the manufacturing method. The feedback mechanisms and handling algorithms are currently being defined. eig

The EDM process • EDM is a metal removal process, either removing material completely using a die (die sinking) or cutting shapes with a wire. • There are many factors which affect the process, many of which are controlled by manufacturer- specific ‘black boxes’. Charmilles Technologies • EDM is also a dynamic technology, with new Robofil 230 developments and research being introduced regularly. • These last two factors are helped by STEP-NC because the manufacturer can adapt the manufacturing strategy to the capabilities of the machine eig

Wire EDM technology • Wire EDM is the more complicated of the two processes, so work has concentrated on that. • Cutting with EDM involves moving the wire relative to the piece, letting the sparks erode a channel. The width of the channel depends on the speed of motion, etc. • There is usually one roughing cut followed by finishing cuts to refine the surface eig

Wire EDM Data Model Workplan machining_workingstep machining_feature wire_edm_machining_operation wire tool workpiece wire_edm_technology … general_path general_path_pocket region_surface_list wire_edm_strategy cut_through slug_removal backmotion eig

B. Advanced functions for wire EDM CAM/SFP systems � Wire offset calculation Today : With the machining features described as two 2D contours in two planes (general_path), the wire offset is calculated in 2D with a constant distance. Example in which this calculation is not applicable: � Geometrical features must be described by ruled surfaces eig

Intelligent functions for determining the path • Instead of giving explicit paths it is possible to determine the paths from the faces to be cut. • Full geometric description provides a basis for adapting control strategies to the capabilities and potentials of the machine. • Control information evolves with the machine, reducing the time lag needed for CAM systems to catch up with developments. Source: Use only when needed, otherwise remove this textbox. eig

B. Advanced functions for wire EDM CAM/SFP systems � Collision detection of the wire with adjacent surfaces Implementation of efficient collision detection and avoidance algorithms to generate the right offset wire path in order to generate the desired adjacent surfaces. Solid eig

C. Feedback of modified NC programs for wire EDM CAD/CAM 1 CAD/CAM 2 STEP-NC STEP-NC Server OODB STEP-NC format EDM EDM SFP EDM SFP machine 1 machine 2 system 1 machine 3 system 2 eig

Managing user modifications • In EDM it is sometimes necessary to change toolpaths to avoid problems or to perform experiments with different parameters in order to get the desired result. • Feedback allows operators to feed path changes back Path modification to the CAM system. necessary • Feedback also provides a tool for recording the The small square should be totally history of part manufacture for subsequent analysis. eroded to prevent machining problems Source: Use only when needed, otherwise remove this textbox. eig