© NMISA 2013

Temperature and Length

Pieter Greeff

October 2013

© NMISA 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 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

© NMISA 2013

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?

20°C

http://www.tropical-rainforest-animals.com/Environmental-Pollution.html

• Temperature• Humidity

• Pressure

• Vibration

• Light

• EM

• Dust

• g

• etc

Lab Environment?

What does ISO 1 Specify?

• This International Standard specifies the standard reference temperature for geometrical

product specifications.

• Temperature

• Humidity

• Pressure

• Vibration

• Light

• EM

• Dust

• g

• etc

© NMISA 2013

Temperature and Length:

Thermal Expansion

∆� = �∆�� To achieve accurate and comparable results temperature effects on length

must always be considered

http://www3.imperial.ac.uk/structuralengineering/st

ructprinciples

© NMISA 2013

CTE: Coefficient of Thermal Expansion

∆� = �∆��

http://en.m.wikipedia.org/wiki/File:Gauge_

block_adhesion.jpg

Length uncertainty range for

different CTE uncertainties for a

100 mm steel gauge block

Gauge blocks, wrung together

α: CTE, ppm/°C

ΔT: Change in Temperature, °C

L: unit of length

© NMISA 2013

GBI and CTE

Index Source of UncertaintyRelative

Contribution

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%

http://www.mikes.fi/documents/pics//Gauge_

blocks.jpg

TESA Automatic Gauge Block

Interferometer (GBI)

Table of Relative Uncertainty Contributions,

for a 100 mm steel gauge block

Length Laboratory CMC:

(20 + 0.5L) nm, where L is in mm70 nm, 100 mm gauge block

Gauge blocks

wrung to a

platen

© NMISA 2013

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.

© NMISA 2013

GBI ECS Design Concept

http://www.tellurex.com/

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

© NMISA 2013

ECS with Active Head Radiation Shield

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ECS Control and Components

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ECS: User Interface and Logging

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ECS: Experimental Setup

Gauge Block

Probes

Isolation

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GBI ESC Results: Ability to achieve minimum and maximum temperatures

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GBI ESC Results: Control

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GBI ESC Results: Gradient

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Form and TemperatureSpecifically roundness

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Roundness: Thermal Gradient Theory

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

© NMISA 2013

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

© NMISA 2013

Conclusion and Future Work

http://gconbio.com/

ECS ResultsAble 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 ResultsReduction of probe drift 96%, only by simple of construction of an

enclosure

The Three OptionsTo 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.

© NMISA 2013

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.

© NMISA 2010© NMISA 2013

References

[1] T. Doiron, “Uncertainties Related to Thermal Expansion in Dimensional Metrology,” NCSLI MEASURE, 2006.

[2] J. Bryan, “International Status of Thermal Error Research,” Annals of the CIRP, vol. 39, no. 2, pp. 645-656, 1990.

[3] Mitutoyo, Gauge block with calibrated coefficient of thermal expansion, 2008.

[4] Hexagonmetrology, [Online]. Available: http://www.hexagonmetrology.co.uk/gauge-block-interferometer_819.htm. [Accessed 5 8 2013].

[5] Brown&Sharpe, Technical Reference Manual Automatic Gauge Block Interferometer, Shropshire, 1997.

[6] J. E. Decker and J. R. Pekelsky, “Uncertainty Evaluation of the Measurements of Guage Blocks by Optical Interferometery,” NRC, Canada, 1997.

[7] R. Thalmann and J. Spiller, “A primary roundness measuring machine,” SPIE Proceedings, Recent Developments in Traceable Dimensional Measurements III, vol. 5879, pp. 123-132, 2005.

[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. 165-171, 2000.

[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, 2003.

References