On an equal level: CT measurements reach the accuracy of conventional tactile metrology

Transcription

1 Comparison of CMM with different sensors On an equal level: CT measurements reach the accuracy of conventional tactile metrology Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 1

2 Comparison of CMM with different sensors Comparison regarding: acceptance and reverification (according ISO 10360, VDI/VDE 2630) accuracy in practical use (comparative measurement of calibrated workpieces) inspection process suitability (measuring system analysis, method 1) Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 2

3 Comparison of CMMs with different sensors CMM with tactile sensor CMM with CT sensor Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 3

4 Probing Error tactile CMM, ISO Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 4

5 Probing Error tactile CMM, ISO Parameters for tactile CMM with rotary swivel measuring head: PFTE Probing Error Form (tactile, empirically qualified) PSTE Probing Error Size ( ) PLTE Probing Error Location ( ) Measurement procedure: Probing of 5 spheres each with 25 points in a defined pattern with each of the 5 probe positions. 125 points in total Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 5

6 Probing error tactile CMM, ISO Calculating of parameters: PFTE Probing Error Form (tactile, empirically qualified): association of a sphere to all the 125 points, calculating the difference between the maximum and the minimum difference from the points to the centre of the regression sphere. PFTE = Rmax Rmin PSTE Probing Error Size ( ) difference between the measured diameter and the calibrated diameter PSTE = Da Dr PLTE Probing Error Location ( ) For each of the measured group of 25 points, the regression sphere is calculated, in total five spheres. The spans of the center coordinates (X, Y and Z) of all five balls are calculated. The largest of the three spans provides the multiple probe local deviation Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 6

7 Probing error CMM with CT sensor Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 7

8 Probing error CMM with CT sensor Parameters for CMM with CT sensor using cone beam PF(TS) Probing Error Form (tomographic error, static) PF = Rmax Rmin PSTE Probing Error Size ( ) PS = Da Dr Measurement requirements Sphere diameter 10 20% of measurement space diagonal 6 measurements: (top + center + bottom) x (center + periphery) At least a minimum 25 surface points to generate PF and PS 2 measurements at significant different magnifications Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 8

9 probing error comparison PS TE, = 1µm PF TE = 5µm PL TE, = 3µm PS (TS) = 3µm PF (TS) = 3µm Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 9

10 Length measurement error, tactile CMM Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 10

11 Length measurement error, tactile CMM The length measurement error describes the three dimensional error behaviour of the overall system consisting of: coordinate measuring device and sensor within the entire measurement volume Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 11

12 Length measurement error, tactile CMM Measurement requirements: Measurement of 5 length, in 7 spatial directions, each 3x (105 values) Smallest test length = 30 mm, biggest test length = 66% of measurement space diagonal Z Y X Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 12

13 Length measurement error, tactile CMM Measurements to verify the length error with a tactile CMM Precimen: Step-Gauche Koba 250 X-Axis Z-Axis diagonal Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 13

14 Length measurement error, tactile CMM E TE, MPE = 3µm+L/ Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 14

15 Length measurement error, CMM with CT-sensor Requirements defined in VDI/VDE analogue to ISO : measurement of 5 length, in 7 spatial directions, each 3x at minimum two different magnifications Smallest test length = 30 mm, biggest test length = 66% of measurement space diagonal Determination of the length measurement error involves the use of test specimens with material standards of size such as ball rods with two or more spheres, ball rails (VDI/VDE ) Test Specimen Length measurement error Ball bar CFC with Ruby spheres, DAkkS calibrated Nominal length: 24, 48, 72, 96, 120mm mm Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 15

16 Length measurement error, CMM with CT-sensor Positioning of the specimen Two magnifications Scan1 low magnification Spherefit1 Scan2 high magn. Spherefit 2 Three of 7 spatial directions Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 16

17 Length measurement error, CMM with CT-sensor Results length measurement error: SD MPE(TS) = 4µm+L/100 Prerequisite is the metrology edition including: compensation of linarity of magnification axis by laser compensation of detectorflatness temperature stabilized tube and detector Position deviation, µm +0,5 0,0 0,5 compensated Z-axis Nominal position of magnification axis, mm detector compensation mask Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 17

18 Comparison of the accuracy of the two systems due to averaging effects arising from the large number of permissible probing points in the characteristic, the probing error contribution shall be added separately to length measurement errors that are calculated from more than two probing points per length. PS TE, MPE = 3µm (VDI/VDE ) PF TE, MPE = 5µm PL TE, MPE = 3µm E TE, MPE = 3µm+L/350 (includes completely PE) PS MPE(TS) = 3µm PF MPE(TS) = 3µm SD MPE(TS) = 4µm+L/100 E MPE(TS) = 4µm+ L/100+3µm+3µm (does not include PE completely) = 10µm+L/100 (worst case) Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 18

19 Measuring of calibrated workpieces for comparison Users are advised of the fact that measurement errors can be smaller in measuring test specimens than in measuring real workpieces, because of simplified workpiece geometries idealised material compositions idealised surfaces are used (VDI/VDE ) Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 19

20 Cube shaped workpiece made of aluminum Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 20

21 Comparison in measuring a calibrated workpiece CMM with CT-sensor CMM with tactile probe head Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 21

22 Results calculated from 15 measurements/system CMM 1 mean deviations to calib. values (µm) 360 values in total CMM v tome x m CMM 2 Rmax Size Pos XY Pos Z 2,0 4,0 2,0 Rmax Size Pos XY Pos Z 1,2 0,7 0,6 Rmax Size Pos XY Pos Z 0,9 0,7 0, Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 22

23 Measurement process suitability The most reliable method for determining the material- and geometry-dependent effects consists in measuring calibrated workpieces using the coordinate measuring device with CT sensor and comparing the measured values with the calibrated values. This can be done as part of a measurement process suitability investigation.(vdi/vde ) Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 23

24 Magnesium casing with bores Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 24

25 Inspection process suitability Statistical characterisics of 25 measurements of magnesium casing MSA Method 1, 450 values in total.( following the golden rule of metrology ) (+-) Size, 6 features Form, 3 features Position, 9 features Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 26

26 Summary 1.) Length measurement error per ISO 10360, VDI/VDE 2630 E MPE (TE ) = 3µm+L/350 E MPE(TS) = 10µm+L/100 (worst case) 2.) Comparison by measuring a calibrated workpiece (max µm) E xa=1,8; R=4,0 E xa=1,2; R=1,2 3.) MSA, method 1, v tome x, (max mm) E xa=0,0035, R=0,002, Tol min 0, Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; info@dim-gmbh.de 27

27 Thank you for your attention! Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 28

28 results for better parts Dienste industrielle Messtechnik GmbH; Im Klauenfuß 9, Neckarsulm; 29