METROLOGY - CALIBRATION

METROLOGY - CALIBRATION

1. WHAT IS THE PURPOSE OF CALIBRATION

   • To provide confidence about a measurement instrument's accuracy and repeatability

2. Calibration should be traceable via UKAS accreditation

3. WHAT IS CALIBRATION ABOUT?

   • the instrument
   • information handling
   • data analysis
   • intervals
   • Uncertainties/error analysis
     • error due to calibration should be a maximum of 10% or permissible error of the instrument or measuring process being calibrated
       • 1:10
       • 10X rule
   • environment
   • people

4. More accurate = More expensive

5. Can never measure the true exact value except in CAD

   • Equipment has a tolerance
     • Out by 10 micrometres
     • If we know the tolerance we can compensate

6. CALIBRATION ENVIRONMENT

   • difficult to control
   • Is a function of
     • Temperature
     • Humidity
     • electrostatic fields
     • Human interaction
     • pressure
     • vibration
     • Electromagnetic fields
   • Calibrator must be aware of all potential sources of error

7. Stability is required to process many measurements across time