Develop procedures to determine geometric measurement errors after work-piece machining Dirk Beger, Lisa Groos, Klaus Wendt TIM Workshop, London 5 th November.

Develop procedures to determine geometric measurement errors after work-piece machining Dirk Beger, Lisa Groos, Klaus Wendt TIM Workshop, London 5 th November 2014

of 27 Traceable in-process dimensional measurement Objective: traceability of dimensional 3D measurements on machine tools Requirement: reliable and traceable measurement uncertainties; target accuracy 5 µm/m Challenge:harsh environmental conditions e.g. no air-conditioning Methods:use of different material standards different procedures climate simulation chamber Source: renishaw.com

of 27 Benefits of on-machine measurement finish machining finish machining on-machine measurement on-machine measurement re-machining ? dismount workpiece dismount workpiece remount workpiece remount workpiece measuring room measuring room workpiece coordinate setting workpiece coordinate setting workpiece coordinate setting workpiece coordinate setting Challenge: measurement under shop floor conditions complex determination of measurement uncertainty Benefit: shortened measurement duration reduction of energy costs (no expensive air-conditioning) Target accuracy: 5 µm/m

of 27 Procedures volumetric error mapping mapping of geometric errors across the entire working volume (generally requires a mathematical error model) verification of MPE validation of error compensation and MPE compliance test (ISO 230-6, ISO 230-10) task-specific error mapping and correction determination of size, form and position errors of shape measurements / typical geometric features (generally does not require a mathematical error model) Source: Hüser et al., 1996 x y z D3D3 D4D4 D1D1 D2D2 Source: Modified from ISO 230-6

of 27 Procedures task-specific measurement uncertainty determination of measurement uncertainty for shape and form measurements / typical geometric features fitness-of-purpose assessment of the capability of a machine tool to measure geometric features with sufficient small accuracy compared to the required manufacturing tolerance lower specification limit upper specification limit work piece tolerance non- conformity uncertainty region uncertainty region non- conformity measurement uncertainty measurement uncertainty measurement uncertainty operator machine tool probing system measuring method environment workpiece

of 27 Correlation: procedure, standard and error procedurematerial standards error sources volumetric error mapping verification of MPE geometric, thermo-mechanical task-specific error mapping task-specific measurement uncertainty + dynamic forces + motion control + control software fitness-of-purpose ++ loads ++ heat Source: eµmetron

of 27 Geometric errors of linear and rotary axes – ISO 230-1 6 error motions E AX roll E BX yaw E CX pitch E XX positioning E YX vertical straightness E ZX horizontal straightness + 3 location / orientation errors 6 error motions E AC tilt E BC tilt E CC angular positioning E XC radial E YC radial E ZC axial + 5 location / orientation errors

of 27 Determination of machine tool errors using a hole plate thermo-invariant Zerodur® hole plate hole plate made of Zerodur® mapping of error motions and location/orientation errors (ISO 230-1) volumetric errors are determined for temperatures between 15° and 45° (use of mobile climate simulation chamber)

of 27 Determination of machine tool errors using a hole plate systematic evaluation of the geometric errors based on measurements of a hole plate in four positions developed for coordinate measurement machines at the PTB more information (e.g.): A reference object based method to determine the parametric error components of coordinate measuring machines and machine tools E. Trapet and F. Wäldele Measurement Vol. 9 No. 1, pp. 17-22 (1989) Linear axes subsystem:

of 27 Determination of machine tool errors using a hole plate Rotary axis subsystem: x y Approach: measure coordinates of at least 3 points Assumption: errors of linear axes already corrected

of 27 Determination of machine tool errors using a hole plate Rotary axis subsystem: x y Approach: measure coordinates of at least 3 points rotation around C-axis and measurement of the chosen points Assumption: errors of linear axes already corrected

of 27 Approach: measure coordinates of at least 3 points rotation around C-axis and measurement of the chosen points description of the rotation with homogeneous transformation matrices yields: Determination of machine tool errors using a hole plate Rotary axis subsystem: calculation of errors by a Gaussian fit (method of least-squares) x y Assumption: errors of linear axes already corrected

of 27 Determination of measurement uncertainty Approach: use of Monte-Carlo-Simulation within a virtual machine tool → expanded measurement uncertainty U (of type B according to GUM) Advantage: determine smallest measurable tolerance T min in advance via G: limiting value specified by user

of 27 Task-specific error compensation – material standard close to zero thermal expansion (made from Zerodur®) specifications: form errors< 1 µm roughness < 0.2 µm position and size of features will be calibrated on CMM measurement tasks: hole flat surface coaxiality Traceability for tactile measurements Traceability for optical measurements extremely low coefficient of thermal expansion (made from Invar) specifications: plated surface form errors < 5 µm position and size of features will be calibrated on CMM, accuracy ̴ 2 µm measurement tasks: hemisphere, cylinder, cone flat and perturbed surfaces

of 27 Task-specific error compensation – concept Approach: Calibrated artefact acquire local error vectors by measuring a calibrated artefact (e.g. Zerodur® Multi-Feature-Check or a workpiece replica)

of 27 Task-specific error compensation – concept Real workpiece measure real workpiece using tactile or optical probe use the local error vector to correct the points measured point by point evaluation of the corrected points Approach: Calibrated artefact acquire local error vectors by measuring a calibrated artefact (e.g. Zerodur® Multi-Feature-Check or a workpiece replica)

of 27 Task-specific error compensation – concept Real workpiece measure real workpiece using tactile or optical probe use the local error vector to correct the points measured point by point evaluation of the corrected points Approach: Calibrated artefact acquire local error vectors by measuring a calibrated artefact (e.g. Zerodur® Multi-Feature-Check or a workpiece replica) Advantage no specific geometric error model of the machine tool is required

of 27 Task-specific error compensation Design CAD model Manufacture 5-axis machine tool Measure task-specific errors Software interface Adjustment of manufacturing parameters in numerical control for on-line error correction

of 27 Task-specific error compensation Design CAD model Manufacture 5-axis machine tool Measure task-specific errors Software interface Adjustment of manufacturing parameters in numerical control for on-line error correction Adjust CAD model

of 27 Fitness-of-purpose within tolerance uncertainty region region of conformity lower specification limit specification phase verification phase region of non-conformity region of non-conformity work piece tolerance out of tolerance increasing measurement uncertainty U uncertainty region upper specification limit Illustration adapted from ISO 14253-1

of 27 Assessing fitness-of-purpose – concept Experimental determination of measurement uncertainty by workpiece replica material standard (WR-MS) according to ISO 15530-3: Manufacturing of WR-MS on machine tool Repeated measuring of WR-MS on machine tool Calibration of WR-MS on a CMM Additional error sources: Loads and internal heat sources

of 27 Assessing fitness-of-purpose – concept Experimental determination of measurement uncertainty by workpiece replica material standard (WR-MS) according to ISO 15530-3: Manufacturing of WR-MS on machine tool Repeated measuring of WR-MS on machine tool Calibration of WR-MS on a CMM Additional error sources: Loads and internal heat sources Mean value + standard deviation of size, form or position measurements Reference result for size, form or position + calibration uncertainty u

of 27 Assessing fitness-of-purpose – concept Experimental determination of measurement uncertainty by workpiece replica material standard (WR-MS) according to ISO 15530-3: Manufacturing of WR-MS on machine tool Repeated measuring of WR-MS on machine tool Calibration of WR-MS on a CMM ISO 15530-3 Additional error sources: Loads and internal heat sources Fitness-of-purpose: U/T ≤ G Mean value + standard deviation of size, form or position measurements Reference result for size, form or position + calibration uncertainty u Additional uncertainties u w from manufacturing process Systematic error: Expanded measurement uncertainty:

of 27 Conclusions Geometric errors of machine tool axes can be systematically mapped using a hole plate for instance, which allows to assess the task-specific measurement uncertainty by a virtual CMM / MT for instance → determination of smallest measurable tolerance Task-specific error mapping allows improving manufacturing accuracy → by adjustment of manufacturing parameters Measurement uncertainty can be experimentally determined by repeated measurements of calibrated artefacts → fitness-of-purpose Ensure traceability of dimensional 3D measurements on machine tools for quality assurance.

Physikalisch-Technische Bundesanstalt Bundesallee 100 38116 Braunschweig, Germany Dirk Beger, Lisa Groos, Klaus Wendt Working Group 5.32 Coordinate Measuring Machines Phone:+49 531 592-5349 E-mail: dirk.beger@ptb.de www.ptb.de As of: 10/2014

of 27 References Hüser, D., Trapet, E., Wäldele, F., Wiegand, U., 1996, Kalibrierung von Koordinatenmessgeräten mit Kugel- und Lochplatten: Anleitung für DKD- Laboratorien, Braunschweig. Trapet, E., Wäldele, F., 1989, A reference object based method to determine the parametric error components of coordinate measuring machines and machine tools, Measurement, Vol. 9, No. 1, 17-22. Wendt, K., Franke, M., Härtig, F., 2012, Measuring large 3D structures using four portable tracking laser interferometers, Measurement, Vol. 45, No. 10, 2339-2345.

of 27 Task-specific error compensation – concept Calibrated artefact Measuring large 3D structures using four portable tracking laser interferometers K. Wendt, M. Franke, F. Härtig MEASUREMENT Vol. 45 No. 10 pp. 2339-2345 (2012) Approach: acquire local error vectors by measuring a calibrated artefact (e.g. Zerodur® Multi-Feature- Check or a workpiece replica)

of 27 Task-specific error compensation – concept Calibrated artefact Real workpiece Measuring large 3D structures using four portable tracking laser interferometers K. Wendt, M. Franke, F. Härtig MEASUREMENT Vol. 45 No. 10 pp. 2339-2345 (2012) Approach: acquire local error vectors by measuring a calibrated artefact (e.g. Zerodur® Multi-Feature- Check or a workpiece replica) measure real workpiece using tactile or optical probe use the local error vector to correct the points measured point by point evaluation of the corrected points

of 27 Task-specific error compensation – concept Calibrated artefact Real workpiece Advantage: no specific geometric error model of the machine tool is required Measuring large 3D structures using four portable tracking laser interferometers K. Wendt, M. Franke, F. Härtig MEASUREMENT Vol. 45 No. 10 pp. 2339-2345 (2012) Approach: acquire local error vectors by measuring a calibrated artefact (e.g. Zerodur® Multi-Feature- Check or a workpiece replica) measure real workpiece using tactile or optical probe use the local error vector to correct the points measured point by point evaluation of the corrected points

Develop procedures to determine geometric measurement errors after work-piece machining Dirk Beger, Lisa Groos, Klaus Wendt TIM Workshop, London 5 th November.

Similar presentations

Presentation on theme: "Develop procedures to determine geometric measurement errors after work-piece machining Dirk Beger, Lisa Groos, Klaus Wendt TIM Workshop, London 5 th November."— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Develop procedures to determine geometric measurement errors after work-piece machining Dirk Beger, Lisa Groos, Klaus Wendt TIM Workshop, London 5 th November.

Similar presentations

Presentation on theme: "Develop procedures to determine geometric measurement errors after work-piece machining Dirk Beger, Lisa Groos, Klaus Wendt TIM Workshop, London 5 th November."— Presentation transcript:

Similar presentations

About project

Feedback