Temperature and Length. Pieter Greeff October 2013

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1 Temperature and Length Pieter Greeff October 2013

Temperature and Length: Main Content Temperature Effects on Length and Form Measurements Motivation and ISO 1 CTE Uncertainty Temperature Measurement GBI ECS Requirements and Design Control

2 Temperature and Length: Main Content Temperature Effects on Length and Form Measurements Motivation and ISO 1 CTE Uncertainty Temperature Measurement GBI ECS Requirements and Design Control Principal Temperature Gradient Effect on Roundness Measurements Temporal and Spatial Results GBI ECS Spindle Roundness versus Room Temperature Roundness Probe Drift Conclusion and Future Work

Introduction: Motivation and ISO 1 At the moment, what are we doing to improve: Our knowledge of the environmental effects? Our ability to improve the current environment? http://www.

3 Introduction: Motivation and ISO 1 At the moment, what are we doing to improve: Our knowledge of the environmental effects? Our ability to improve the current environment? What does ISO 1 Specify? Lab Environment? Temperature Humidity Pressure Vibration Vibration Light Light EM EM Dust g etc This International Standard specifies the standard reference temperature for geometrical product specifications. Humidity Pressure Dust g etc 20 C

4 Temperature and Length: Thermal Expansion = To achieve accurate and comparable results temperature effects on length must always be considered ructprinciples

CTE: Coefficient of Thermal Expansion = α:

5 CTE: Coefficient of Thermal Expansion = α: CTE, ppm/ C ΔT: Change in Temperature, C L: unit of length Gauge blocks, wrung together block_adhesion.jpg Length uncertainty range for different CTE uncertainties for a 100 mm steel gauge block

GBI and CTE Index Source of Uncertainty TESA Automatic Gauge Block Interferometer (GBI) Table of Relative Uncertainty Contributions, for a 100 mm steel gauge block

$5L) nm, where L is in mm 70 nm, 100 mm gauge block 1 Laser Frequency 0,0% 2 Fringe Factor 0,3% 3 Gauge Temperature 14,9% 4 CTE 70,4% 5 Temperature (Refractive index of$

6 GBI and CTE Index Source of Uncertainty TESA Automatic Gauge Block Interferometer (GBI) Table of Relative Uncertainty Contributions, for a 100 mm steel gauge block Relative Contribution Length Laboratory CMC: ( L) nm, where L is in mm 70 nm, 100 mm gauge block 1 Laser Frequency 0,0% 2 Fringe Factor 0,3% 3 Gauge Temperature 14,9% 4 CTE 70,4% 5 Temperature (Refractive index of air) 0,0% 6 Pressure (Refractive index of air) 0,0% 7 Humidity (Refractive index of air) 0,0% 8 Parallelism/Flatness 0,2% 9 Optics/Aberrations 1,8% 10 Phase Correction 3,8% 11 Wringing Film 8,5% 12 Repeatability 0,1% Gauge blocks wrung to a platen blocks.jpg

7 Temperature Measurements If you are measuring precisely 20 C, does that mean that your whole gauge block is now at 20 C? 1. Stabilisation time. Stabilisation time assumes a constant environment and that the actual measurement will not induce a large temperature change of the UUT or reference. It should be long enough to ensure a predictable stable temperature. 2. Temperature Gradient. The temperature gradient can be measured by placing a sufficient number of probes along the measurement axis. 3. Contact Thermal Resistance. The distance between probe and UUT should be minimized, including air or other insulating gaps. This includes taking into consideration contact thermal resistance. 4. Thermometer Calibration. Thermometers are calibrated in ideal laboratory conditions and this is most likely not the same as their operational environment.

measure and log the control volume temperature accurately (±50 mk), within an environment of (20 ± 1) C Main Components: 1.

8 GBI ECS Design Concept Environmental Control System (ECS) Design, develop and test a cost effective chamber which can: 1. Control temperature 15 C to 25 C 2. Within ± 0.1 C 3. The ECS should not affect normal GBI operation. 4. measure and log the control volume temperature accurately (±50 mk), within an environment of (20 ± 1) C Main Components: 1. Double walled enclosure, with holes for laser and platen 2. Peltier, Thermo-electric effect temperature controller

9 ECS with Active Head Radiation Shield

10 ECS Control and Components

11 ECS: User Interface and Logging

12 ECS: Experimental Setup Gauge Block Probes Isolation

13 GBI ESC Results: Ability to achieve minimum and maximum temperatures

14 GBI ESC Results: Control

15 GBI ESC Results: Gradient

16 Form and Temperature Specifically roundness

17 Roundness: Thermal Gradient Theory

18 Roundness Results: Spindle RONt and temperature deviation from the reference temperature

19 Roundness Results : Probe drift before and after enclosure Average Range of Drift (nm) Time Step (s) Enclosure Closed, No Contact Enclosure Closed, Contact Enclosure Open, Contact No Enclosure, Stage On, Contact No Enclosure, Stage Off, Contact 10 0,1 0,2 1,2 4,8 5,6 20 0,1 0,4 2,1 8,3 9,2 30 0,2 0,5 2,9 10,2 11,8

Conclusion and Future Work ECS Results Able to both actuate and control the temperature, to address the biggest uncertainty contributor in a 100 mm gauge block Improvement Reduce isolation gap

Reduction of probe drift 96%, only by simple of construction of an enclosure The Three Options To achieve accurate and comparable results temperature effects on length must always be

20 Conclusion and Future Work ECS Results Able to both actuate and control the temperature, to address the biggest uncertainty contributor in a 100 mm gauge block Improvement Reduce isolation gap between actuator and gauge block Reduced control volume Use copper inner wall Improve insolation with an optical parallel and special platen Improve with vacuum design Roundness Results Reduction of probe drift 96%, only by simple of construction of an enclosure The Three Options To achieve accurate and comparable results temperature effects on length must always be considered: 1. Incorporate in the measurement setup (isolation or control), 2. Apply in the measurement result (correction to 20 C) 3. Consider in the measurement uncertainty calculation.

21 Acknowledgements Roko Popich (Mechanical Workshop) for the construction of the roundness enclosure, help with the ESC chamber design and adjustments. Oelof Kruger for expert technical guidance Faith Hungwe for technical revision Floris v.d. Walt for CMM temperature related measurements Hans Liedberg for high accuracy temperature calibrations on short notice.

22 References References [1] T. Doiron, Uncertainties Related to Thermal Expansion in Dimensional Metrology, NCSLI MEASURE, [2] J. Bryan, International Status of Thermal Error Research, Annals of the CIRP, vol. 39, no. 2, pp , [3] Mitutoyo, Gauge block with calibrated coefficient of thermal expansion, [4] Hexagonmetrology, [Online]. Available: [Accessed ]. [5] Brown&Sharpe, Technical Reference Manual Automatic Gauge Block Interferometer, Shropshire, [6] J. E. Decker and J. R. Pekelsky, Uncertainty Evaluation of the Measurements of Guage Blocks by Optical Interferometery, NRC, Canada, [7] R. Thalmann and J. Spiller, A primary roundness measuring machine, SPIE Proceedings, Recent Developments in Traceable Dimensional Measurements III, vol. 5879, pp , [8] M. Okaji, N. Yamada and H. Moriyama, Ultra-precise thermal expansion measurements of ceramic and steel gauge blocks with an interferometric dilatometer, Metrologia, no. 37, pp , [9] J. Unkuri, J. Manninen and A. Lassila, Accurate Linear Thermal Expansion Coefficient Determination By Interferometry, in XVII IMEKO World Congress Metrology in the 3rd Millennium, Dubrovnik, Croatia, NMISA

Temperature and Length

Temperature and Length Speaker / Author: Pieter Greeff NMISA Private Bag X34, Lynnwood Ridge, Pretoria, 0040, RSA e-mail: pgreeff@nmisa.org Phone: 012 841 2299 Abstract The environment, especially temperature,