UNCERTAINTY:

  • All measurements carried out using measuring instruments are affected by an uncertainty.
  • Uncertainty is defined by the standard as “a parameter associated to the measurement result that identify the dispersion of measurement”.
  • Uncertainty of measurement are influenced by many parameters, some coming from the instrument (Accuracy, Resolution. Repeatability…..) some coming from the environment (Temperature, Lighting, Vibration …..) some coming from the measurement method, from the Technician, and from the measured object itself.
  • Every laboratory should be able to evaluate the measurement uncertainty of their own measurement.

 

TOLERANCE:

  • Tolerances are defined by standards, regulation or contracts. Tolerance usually represent a limit to accept or reject something (one sunglass for example).
  • In the modern way to carry out measurements, the metrologists must consider not only measurement results but also measurement uncertainty when they want to accept / reject a piece.