BeginnerTopic 12 of 102Manufacturing, Robotics & Systems
Metrology
The science of measurement, including calibration and uncertainty.
In depth
Metrology covers measurement science: units, standards, traceability to SI, calibration, uncertainty (GUM), repeatability and reproducibility (Gage R&R), CMMs, optical and laser scanners, surface profilometers. Measurement uncertainty must be small relative to tolerance (10:1 rule).
Key points
- Accuracy vs precision
- Calibration hierarchy
- Environmental control (20 °C)
ExampleA CMM inspects a machined housing against a CAD model.
What is Metrology?
The science of measurement, including calibration and uncertainty.
Why is it important to understand metrology?
Metrology provides trusted measurements, so calibration and uncertainty decide whether a result can be relied upon.
What is calibration?
Comparing an instrument with a reference of known accuracy and recording the difference, so readings can be corrected or trusted.
What is measurement uncertainty?
A range within which the true value is expected to lie, which should be stated with every measurement that matters.
How is Metrology used in practice?
Typical applications include calibrating a micrometer against gauge blocks before a production run, estimating the uncertainty of a dimension measured with a coordinate machine and checking the traceability of a gauge to national standards.
What should I learn before Metrology?
Study "Geometric dimensioning and tolerancing" first (topic 11 of 102 in Manufacturing, Robotics & Systems). It covers the groundwork this topic builds on.
What are the key points of Metrology?
Accuracy vs precision. Calibration hierarchy. Environmental control (20 °C).
Can you give an example of Metrology?
A CMM inspects a machined housing against a CAD model.
What comes after Metrology?
The next topic is "Casting", which builds directly on this one.
How difficult is Metrology?
It is classed as Beginner in Manufacturing, Robotics & Systems (topic 12 of 102). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.