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Boeing's Early Implementation Study of AP238 (STEP-NC)

Boeing is examining the capabilities of AP238 to streamline data flow between CAD/CAM systems and CNC machine tools, aiming to transition from "Dumb CNC" to "Smart CNC" operations.

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Boeing's Early Implementation Study of AP238 (STEP-NC)

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  1. Boeing’s AP238 (STEP-NC)Early Implementation Study

  2. TEAM Members • David Odendahl • Paul Pennekamp • Mick Fine • Ming Liu • Waris Jaffery • Joe Page • Al Glasscock – project manager • Ted Schultz – project architect • Mauro Costa • Steve Dostert • Sid Venkatesh • Rich Morihara • Keith Mackay BCA Tulsa Division BCA Wichita 787 Factory Controls Material & Process Tech. BCA Fabrication Division

  3. Special Thanks To • Martin Hardwick • Dave Loffredo • John Michaloski • Fred Proctor • Xun Xu STEP Tools NIST

  4. Boeing is presently examining AP238 to see if the standard’s toolpath description capabilities can be used to streamline the data flow between existing CAD/CAM systems and CNC machine tools. Why???

  5. Present Situation - “Dumb CNC” • Presently, CNC machines receive data defining the axis movement required in order to manufacture a part. This is referred to as MCD or machine control data. • MCD is a very low level of instruction. Traditionally, CNC machines do not have access to higher-level information about the tasks they are executing or the part they are trying to manufacture. • High-level intelligence is only utilized at the CAD and CAM stages of the manufacturing process.

  6. “Dumb CNC” Problems • Not Portable • Unique data must be generated for each machine control combination on which the part is to be run • Not Adaptable • No information is provided to the machine to help it adapt to real-time changes in machining dynamics and machine tool alignment.

  7. Target - “Smart CNC” • Cutter movement data, instead of axis movement data is sent to the CNC. Sophisticated CNCs have the capability of converting cutter movement data to axis movement data. • High level information about the part features, materials, cutters, and dimensional tolerances can also be sent to the CNC. • This information should be sent using a data standard such as: AP238 “STEP-NC”.

  8. Dumb vs. Smart Smart Tool Motion Toolpath Tolerances Spindle Speeds Auxiliary Functions Material Characteristics Fixturing End Result Part Tolerances Cutter information Dumb: Axis Motion Spindle Speeds Auxiliary Functions

  9. Smart CNC Benefits: Portability • Portable • Cutter motion data is “machine neutral” and may be used directly by machines with different geometries • Separate post-processors are not required for each unique control/machine combination • Direct portability between machine tools/controls is possible (within reason)

  10. Portability Issues • Data that is presently sent to a CNC is not portable for two main reasons: • No standard format followed (a bad reason) • Machine geometries vary (used to be a good reason) • Machine auxiliary functions are not implemented in a consistent, standard manner

  11. Tool Motion Vs. Axis Motion On machines with different geometries, different axis motions are required to achieve the same cutter motion relative to the part

  12. “Dumb CNC” Data Flow Catia CL File (Machine Independent) Post Processor Post Processor Post Processor MCD File (Control/Machine Dependent) MCD File (Control/Machine Dependent) MCD File (Control/Machine Dependent) Machine(s) Machine(s) Machine(s)

  13. Smart CNC Data Flow: Transitional Catia CL File (Machine Independent) CL to AP238 Converter Siemens Format converter FANUC Format converter RS-494 Format converter NIST “C on B” Machining Center Machine #1 Machine #2 “C on A” Machining Center 5-Axis Gantry Horizontal Profiler

  14. Smart CNC Data Flow: Final CAM AP 238 File NIST “C on B” Machining Center Machine #1 Machine #2 “C on A” Machining Center 5-Axis Gantry Horizontal Profiler

  15. Demonstration A: Portability • Plan – demonstrate portability • Result – six identical parts from one file AP238 file RS-494 Converter Siemens Format converter FANUC Format converter NIST 5 Axis 5 Axis Machine TBD 5 Axis Machine TBD Boeing 5 Axis 5 Axis Horizontal Profiler 5 Axis Gantry Complete Complete Complete Complete

  16. Test Part for Demonstration A NAS 979 Circle-Diamond-Square combined with a NAS 979 cone test.

  17. Dumb CNC Scenario #1 • Due to increases in rate, an existing machine is no longer able to support required workload. • The machine is no longer manufactured, or it is desired to purchase a similar machine from a different manufacturer or with a different control. • Because the MCD data sent to the machines is non-portable, a separate set of MCD data must be kept and supported for the new machine

  18. Smart CNC Scenario #1 • Due to increases in rate, a machine is no longer able to support the workload. • The machine is no longer manufactured, or it is desired to purchase a similar machine from a different manufacturer or with a different control. • Because the MCD data sent to the machines is portable, the existing MCD data could be used directly on the new, similar machine.

  19. A Wide Data Path • Other information about the part can be transmitted using AP238 • Fixtures • Material • Cutters • Tolerances • Part Geometry • NC Data

  20. Dumb CNC Scenario #2 • Three machines all have different mechanical characteristics. Machine #1, the strongest machine, can handle a cutter load 20% greater than the weakest machine, #3. • Program for the weakest machine, otherwise separate NC programs for each machine would have to be maintained

  21. Smart CNC Scenario #2 • Three machines all have different mechanical characteristics. Machine #1, the strongest machine, can handle a cutter load 20% greater than the weakest machine, #3. • Because, through the AP238 file, the CNC is aware of the tolerances for the final part, the cutter type, and the material to be machined, the CNC can automatically adjust feed and spindle rates to optimize the program for each individual machine.

  22. Demonstration B: “Real World” Practicality • The practicality of using AP238 to define and produce a complex, 5-axis, “real-world” part was unproven • Are file sizes reasonable? • Is processing time reasonable? • Can the required software be produced? • What other problems will be encountered?

  23. Test Part for Demonstration B 5-axis Aerospace Part

  24. Progress to Date • Today’s demonstration Prototype converters for transferring AP238 Part 21 files to Fanuc, Siemens, and BCL formats written. • NAS 979 CDS/Cone test part machined • 5-axis demonstration part machined

  25. NAS 979 CDS/Cone Test Part • CATIA CL file size: 201 KB • AP238 Part 21 file size: 114 KB • NC file size: 45 KB to 104KB • Total processing time: 5 seconds ( 1 GHZ Pentium )

  26. 5-Axis Aerospace part • CATIA CL file size: 2077 KB • AP238 Part 21 file size: 2305 KB • NC file size: 560 KB to 1304 KB • Total processing time: 20 seconds ( 1 GHZ Pentium )

  27. Wichita AP238 Efforts • Wichita test part generated • NC programming to begin soon • Part will be machined on two different machines in Wichita • Part will also be machined in Tulsa

  28. Wichita STEP-NC Part

  29. Caveat AP238 allows DATA portability. It does not guarantee PROCESS portability. • Machine work envelope • Spindle capability • Machining philosophy • Cultural Issues However, much benefit can be shown using AP238 to describe SIMILAR processes

  30. Questions?

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