Precision Measurement and Calibration Fundamentals
Calibration Fundamentals
To ensure accurate measurements, measuring instruments must be contrasted against approved standards. This process is known as calibration.
Common Measuring Tools
- Ruler: A tool for taking measurements where physical divisions and subdivisions represent actual units of length on a scale.
- Caliper: A delicate precision instrument that requires careful handling to maintain accuracy.
Using a Caliper Correctly
When using a caliper, ensure the legs maintain firm contact with the part being measured. Use the fixed leg as a reference point and move the mobile leg until contact is achieved. Always ensure the rule of the gauge is aligned with the surfaces being measured.
Types of Caliper Measurements
- Exterior and interior dimensions
- Heights
- Collars and slots
- Central plotting and marking
Types of Gauges
- Clock gauges
- Depth gauges
- Digital depth gauges
- Specialized calipers
Key Metrology Definitions
- Measurement: The set of operations intended to determine the value of a quantity.
- Verification: Confirmation by examination and provision of tangible evidence that specific requirements have been met.
- Accuracy: The ability of an instrument to provide indications close to the true value, accounting for both systematic and random errors.
- Repeatability: The degree of concordance between results of successive measurements of the same magnitude using the same method, instruments, and location.
- Resolution: The minimum value of a divided scale or the last significant digit shown on digital systems.
- Sensitivity: The ratio of the observed increase in an instrument's output to the corresponding increase in the measured quantity.
- Measuring Range: The set of values that can be measured by a specific instrument.