step nc tool path programming in an intelligent step nc manufacturing context
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STEP NC
Tool path programming in an intelligent Step NC Manufacturing Context
Adopted and edited from a presentation made by:Raphaël LAGUIONIE - Matthieu RAUCH – Jean-Yves HASCOET
Institut Recherche Communications Cybernetique Nantes (IRCCyN) France.
Scope
Introduction & Applications
Step_NC: A new approach– Lacks of curent G-code– A new vision: Step_NC– Machining strategies in a Step_NC file– The Korean Step_NC prototype
Pattern strategies– A new method to build toolpaths– Proposition of integration in Step_NC standard
Validation of the proposition– Implementation in PosSFP (Shop Floor Programming System)– Development of a Step_NC numerical chain– From the CAD model to the machined part…
Conclusion
IntroductionThe STEP-NC AP238 StandardThe STEP-NC AP238 standard is the result of a ten year international effort to replace the RS274D (ISO 6983) M and G code standard with a modern associative language that connects the CAD design data used to determine the machining requirements for an operation with the CAM process data that solves those requirements.
Enabling e-Manufacturing for Mechanical PartsSTEP-NC allows manufacturing organizations to seamlessly share machining and measurement information between machines and over the Internet. The emerging STEP-NC technology is yielding process improvements including a 15% reduction in machining time. The automated measurement and compensation enabled by STEP-NC promises to yield parts that meet higher accuracy requirements for less cost. The integrated simulation and verification enabled by STEP-NC promises to guarantee that every part will be made correctly and that production will stop whenever cuts are about to be made that do not meets design requirements.
Resources: Step Tools, Inc. http://www.steptools.com/library/stepnc/
Working Steps & AdvanctagesWorking StepsSTEP-NC changes the way that manufacturing is done by defining data as "working steps": a library of specific operations that might be performed on a CNC machine tool. In other words, it breaks down every machining operation into the steps required to perform the operation. In the past, CNC machine tools had to be programmed using G and M codes (from ISO 6983), which were instructions that only told the machine what moves to make, without any semantic content that referred to the part being processed. STEP-NC will make G and M codes obsolete.
AdvantagesWith the concept of "working steps" in place, the manufacturing process becomes streamlined. Now, a machine tool can receive a file with STEP-NC data, "know" what it means, and proceed milling the piece without any more instructions. There will be no more programming the machine tool for each individual piece. Moreover, the benefit of the standard goes further. With a set of standard "working steps" in place, all manufacturers will be able to share information reliably and instantaneously. A STEP-NC converted CAD file that is completed on the east coast can be sent over the internet to a machine shop on the west coast and they can immediately start milling the part.
Resources: Step Tools, Inc. http://www.steptools.com/library/stepnc/
Applications
Step NC will enable:-• Smart Process Control
• Smart Process Monitoring• Smart Manufacturing
The current programming standard : G-code
CAM Post-processor
M216 G0 Z25 G0 X50 Y60 G1 X95 M02
G-Code
• Based on principles of the 60’s
• Ambiguous semantics in some cases
• Vendor-specific extensions
• Difficulty of changes on the machine tool
• Impossible Feed back
• Use of post-processors
As many configurations as CAM softwares / machine tools
• more than 4500 today
Step_NC: a new approach
Benefits of Step_NC A new vision of the numerical chain
Total integration of CAD-CAM-CNC
Total integration of CAD-CAM-CNC
No information lost
No information lost
Implementation of a single file
Implementation of a single file
Bidirectional data flow
Bidirectional data flow
DesignProduction Planning
Production
CAD
Simulation
Step_NC
CNC
CAM
Step_NC: a new approach
• No more post-processors, no G & M codes• Machine-unspecific program• No more post-processors, no G & M codes• Machine-unspecific program
Comparison G code – Step_NC
CAD/CAM
Post-Processeur
CAO/FAO
Shoop floor
Design NC planning
Step_NC
bidirectional data flow
Curent Standard : G codes Step_NC StandardDescription of
entitiesToolpaths description
Step_NC: a new approach
CNC in Step_NC numerical chain
Axis command
Part machining
Operations schedulingToolpaths generation
Machine tools characteristics
Data process estimationEntity
geametryMachining parameters
ToolsWorplan Etc.
Read of Step_CN file
Step_NC
Simulation
CAM
CAD
CNC
Step_NC: a new approach
Structure of a Step_NC file
…
Step_NC: a new approach
Korean prototype of Step_NC numerical chain
11
PosSFP :
Feature recognition
Choice of machining strategies attributes
Step_NC file generation
Machining entities
Step_NC: a new approach
Study situation in Step_NC development
Interpreted Step_NC programming
Step_NC Interpreter
G-code CNC
G-code File
Interpretation Read File
Axis command
Operations schedulingToolpaths generation Post processing
Part machining
Step_NCfile
Integrated Step_NC programming
CNC
Interpretation Axis command Part machining
Machine tool characteristics
Résultats de mesure ou autres données pièce
Operations schedulingToolpaths generation
Step_NCfile
Advanced Step_NC programming
CNC
Interpretation
Process data estimation
Axis command Part machiningOperations schedulingToolpaths generationStep_NC
file
Machine tool characteristics
First step :
Goal :
Interpreted programming
Evolution with :
Integrated programming
Advanced programming
Step_NC: a new approach
First step : Contribution to standard development
Enrichment of strategies proposed in Step_NC :
Unidirectional
Contour-bidirectional
Center millingContour
spiralContour parallel
Bidirectional
Bidirectional-contour Explicit
All others strategies
Pattern strategies : GUIDE CURVE + PATTERN
Exemples of strategies built on pattern curves :
Trochoïdal
milling :
Plunge
milling :
Pattern strategies : a new method to build toolpaths
Validation of this proposition of integration
14
CAD part
Machining
PosSFPReading
tools
Toolpath
generation Adaptation
Step 1 :Implementation of trochoidal milling in : - Step_NC Standard - PosSFP
Step 2 :Building of reading tools and toolpaths generators
Step 3 :Machining test parts
Step_NC
Strategy parameters Toolpaths
Step_NC File
Integration of pattern strategies in Step_NC
Conclusion & More Benefits of Step NC
• Creation of an interpreted Step NC numerical chain
• First Step through advanced programming
• possibility to work with Step NC on conventional means
• Interest of pattern strategies
• Generation simplicity
• Few attributes needed to generate a complete toolpath
• Easy portability
• Compatibility with Step NC standard and high level programming
• Enrichment of Step NC possibilities
Pattern strategies
Step NC
Conclusion
- G-code programming is no more the solution
- Bidirectional data flow
- 1 single file (no lost of data, no redundancy, etc.)
- Less correction time
- Step_NC file portability
- Total integration of CNC – feed-back to design and NC planning
- Capitalization of shop floor feedbacks and experiences
- New possibilities for toolpath generation and machining strategies
- Ability of real-time adaptation and optimization of toolpaths and machining parameters
Advanced Step NC
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