using a low force 3D touch probe

Transcription

1 Federal Department of Justice and Police FDJP Federal Office of Metrology METAS Ultra precision µcmm using a low force 3D touch probe F. Meli, A. Küng, R. Thalmann Federal Office of Metrology (METAS)

2 Ultra precision µcmm using a low force 3D touch probe Contents: Probing force and surface damage Low force 3D-probe head Ultraprecision CMM Probe sphere calibration Scanning CENAM CMM Club I R. Thalmann I I 2

3 Tactile measurements of small objects Application fields: Micro technology Micro- and fiber-optics Data storage Watch industry Medical industry Automotive industry CENAM CMM Club I R. Thalmann I I 3

4 Surface deformation at tactile probing The smaller the probe sphere the larger the surface pressure at contact the larger the risc of plastic deformation CENAM CMM Club I R. Thalmann I I 4

5 Maximum Force versus sphere diameter Hertz theory assuming a contact pressure of 1000 MPa force /mn p = 1000 MPa sphere diameter /mm Ø 4.0: 3.6 N Ø 0.3: 22 mn Ø 0.2: 10 mn Ø 0.1: 2.5 mn low stiffness CENAM CMM Club I R. Thalmann I I 5

6 Experimental verification by AFM Conditions: conventional high end CMM with analogue probe (SIP) Ø 0.6 mm probe material aluminium depth: 330 nm CENAM CMM Club I R. Thalmann I I 6

7 Dynamic forces m= v 2 Y 5 E *4 db 3 v Y E = * = approach speed = tensile equivalent yield strength Young' s modulus Ref.: W.P. van Vliet et al., Annals of CIRP, Vol. 45/1, 1996, p. 483 CENAM CMM Club I R. Thalmann I I 7

8 Maximum probe mass versus sphere diameter contact pressure: 1000 MPa probe mass /g v = 0.1 mm/s v = 0.5 mm/s v = 1.0 mm/s v = 1 mm/s: Ø 4 mm m = 1.8 kg Ø 0.1 mm m = 28 mg slower! v = 0.1 mm/s: Ø 0.1 mm m = 2.8 g sphere diameter /mm CENAM CMM Club I R. Thalmann I I 8

9 Probe design and kinematics (know how) Clavel, Patent n A5 CENAM CMM Club I R. Thalmann I I 9

10 Probe sensor design CENAM CMM Club I R. Thalmann I I 10

11 Probe coordinate system X Y Z CMM CMM CMM = X = = X P P Y Y Y P P P Z Z Z P P P CENAM CMM Club I R. Thalmann I I 11

12 The measurement procedure contact contact CENAM CMM Club I R. Thalmann I I 12

13 Ultraprecision CMM project of Philips CFT Abbe principle: probe sphere x z x interferometer beams Theo Ruijl, Ultraprecision Coordinate Measuring Machine Thesis, Philips CFT, Eindhoven, The Netherlands CENAM CMM Club I R. Thalmann I I 13

14 Ultraprecision CMM project of Philips CFT Metrology loop: Theo Ruijl, Ultraprecision Coordinate Measuring Machine Thesis, Philips CFT, Eindhoven, The Netherlands CENAM CMM Club I R. Thalmann I I 14

15 Ultraprecision CMM project of Philips CFT Theo Ruijl, Ultraprecision Coordinate Measuring Machine Thesis, Philips CFT, Eindhoven, The Netherlands CENAM CMM Club I R. Thalmann I I 15

16 New machine controller made at METAS High Level LAN Machine Controller Quindos LabView HP Interferometer Boards (ISA) 3-axis motion control (PCI) Stage gravity compensation Probe head interface (PXI) Refraction Index (p, T air, H rel, CO 2 ) Material and Frame Temperatures Joystick Security and resources error corrections metrology know how CENAM CMM Club I R. Thalmann I I 16

17 Calibrations and corrections Goal: Traceable measurements Laser wavelength Interferometer alignment: cosine, Abbe, guiding errors Ambient: Temperature, pressure, humidity, CO 2 Reference mirror-system Probing sphere calibration pitch Y-Axix Y axis angular drift /sec y = x x Y axis position /mm CENAM CMM Club I R. Thalmann I I 17

18 Flatness corrections of reference mirrors X- Axis form error = 51 nm Y- Axis form error = 63 nm Z- Axis form error = 233 nm CENAM CMM Club I R. Thalmann I I 18

19 Measurement on 0.5 mm sphere roundness of the measured sphere (nm) Average Sphere diameter: 0.5 mm, roundness 64 nm Measured in 6 orientations St. dev. = 9.8 nm CENAM CMM Club I R. Thalmann I I 19

20 Measurement on 0.5 mm sphere roundness of the probing sphere (nm) Average Probe diameter: 0.3 mm, roundness 40 nm Measured in 6 orientations St. dev. = 8.4 nm CENAM CMM Club I R. Thalmann I I 20

21 Extended set of probes ranging from 1 mm to mm 1 mm 125 µm CENAM CMM Club I R. Thalmann I I 21

22 Probe diameter determination using 3 spheres Ma = R1a + R2a probe sphere y Mb = R1a + R3a Mc = R2a + R3a z object sphere Ma x x z y x α α x R1a R2a R3a Side view Top view CENAM CMM Club I R. Thalmann I I 22

23 Absolute calibration of 3 reference spheres The 3 spheres were measured against each other providing, by means of an error separation technique, an absolute mapping of their dimension. Equator of sphere 1 Diameter: mm Roundness: 48 nm Equator of sphere 2 Diameter: mm Roundness: 26 nm Equator of sphere 3 Diameter: mm Roundness: 34 nm Error magnification: CENAM CMM Club I R. Thalmann I I 23

24 Absolute calibration of 3 reference spheres Sphere 2 Diameter: Roundness: mm 33 nm Sphere 1 Sphere 3 Diameter: mm Diameter: mm Roundness: 51 nm Roundness: 53 nm CENAM CMM Club I R. Thalmann I I 24

25 Controlled Freeform-Scanning Scan speed 0.1 mm/s to 0.6 mm/s point density up to 300 p/mm propagation deflection Scanning points CENAM CMM Club I R. Thalmann I I 25

26 ISO scanning acceptance test Form Error: 87 nm Sphericity: 60 nm Surf. roughness: 15 nm Calibration error: 15 nm CENAM CMM Club I R. Thalmann I I 26

27 Scanning of a 1 mm sphere equator 10 scan measurements with a Ø 0.3 mm probe repeatability : 5 nm (1σ) surface texture : ~10 nm equator form error :48 nm Cir 10 Cir 9 Cir 8 Cir 7 Cir 6 Cir 5 Cir 4 Cir 3 Cir 2 Cir CENAM CMM Club I R. Thalmann I I 27

28 Roundness comparison measurement Form error: Filtered with 50 upr Talyrond 73: (93 ± 10) nm µcmm: (90 ± 20) nm Deviation to average diameter (mm) Difference: Max: 15 nm St. dev.: 5 nm Talyround Scanning 0 Scanning 120 Scanning 240 Average scanning CENAM CMM Club I R. Thalmann I I 28

29 CENAM CMM Club I R. Thalmann I I 29 Thank you