Temperature and Dimensional Metrology: Unceretainty and Productivity

Abstract

Mitutoyo America built a new dimensional calibration laboratory in 2013 that features much tighter temperature control than the prior laboratory. This paper is a case study in improving temperature control and the impact on dimensional measurements. The new laboratory is a high level laboratory with tight temperature control of 20±0.1°C, but the concepts presented in this paper apply to any level of improvements in temperature control in dimensional calibration or inspection laboratories. This paper will first discuss the justification presented to management for the temperature control, which included a carefully developed analysis of the projected improvements in measurement uncertainty. The process of specifying and verifying the environment will then be briefly discussed, followed by a presentation of the complex testing of the measurement processes to assess the actual improvements in the measurement uncertainty. The same processes and equipment, used in the two different environments, will be presented. Finally, this paper will discuss the somewhat surprising benefit of gains in productivity tied to improvements in temperature control, which has allowed certain calibrations to be completed with fewer repeat runs and therefore much more quickly. The improved temperature control has therefore not only allowed the measurement uncertainty to be reduced to desired targets but has also led to modifications in measurement procedures that have improved productivity and reduced costs.