ENGINEERING METROLOGY TOOLBOX  
 Temperature Tutorial 
 Slide 13 

Temperature Tutorial is a web-based tutorial about effects of temperature on dimensional measurements.

Temperature Tutorial
Slide 13

First SlidePrevious SlideNext SlideLast SlideTemperature Tutorial IndexEngineering Metrology Toolbox Home

Summary

1. All materials change size with temperature change, and over small temperature changes the relative size change (DL/L) is proportional to the temperature change, and the proportionality constant is the Coefficient of Thermal Expansion (CTE).

2. The CTE is very dependent on the details of the makeup of the material. Generic terms like "steel" or "ceramic" are virtually useless.

3. Given the exact type of material (e.g. AISI 52100 Steel) the CTE can be looked up in reference books, or sometimes obtained from the manufacturer. The uncertainty of the number is generally not available.

4. Reference books and manufacturers generally have the average CTE over some temperature range. Often the range contains the dimensional reference temperature of 20 °C, but the value at 20 °C is seldom available. Book values generally are the average over at least 80 °C, and often 3 or 4 times as much. Since most metals have CTE that rise with temperature, an average CTE for 20-100 °C is generally biased if used at room temperature. This bias is typically a few percent, but using an average CTE over larger temperature ranges can result in biases of 10% or more.

First SlidePrevious SlideNext SlideLast SlideTemperature Tutorial IndexEngineering Metrology Toolbox Home
Return to Top of Slide
Return to Top of Document

Web Site Home: Engineering Metrology Toolbox
Technical Inquiries: Daniel S. Sawyer, Group Leader
Dimensional Metrology
Engineering Physics Division
Physical Measurement Laboratory
NIST, 100 Bureau Drive, Stop 8211, Gaithersburg, MD 20899-8211

The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.
NIST / PML / Engineering Physics Division

NIST Program Questions: Public Inquires Unit
(301) 975-NIST (6478) TTY (301) 975-8295
NIST, 100 Bureau Drive, Stop 3460, Gaithersburg, MD 20899-3460

Privacy Policy / Security Notice / Accessibility Statement / Disclaimer / Freedom of Information Act (FOIA) / 
Environmental Policy Statement / No Fear Act Policy / NIST Information Quality Standards / Scientific Integrity Summary

Date Created: Monday, October 15, 2001
Last Updated: Tuesday, November 09, 2004
Technical Web Site Questions: Jay Zimmerman
Feedback and Comments: Webmaster