Metrology Tools and Accuracy in Manufacturing

Study Notes

Essential parameters for inspection include dimensional accuracy, geometrical form accuracy (flat, cylindrical, taper, and spherical surfaces), surface waviness, and geometry structure (surface roughness and micro geometry).
Metrology tools like coordinate measuring machines (CMMs), laser scanners, and optical comparators are utilized for measuring geometric features.
Quality control involves comparing measured features to specified tolerances and may use statistical process control (SPC) for maintaining consistency during production.

Straightness refers to the shortest distance between two points, ideally represented by a straight line.
Measurement of straightness involves comparing to a straight edge or using a calibrated tool; gauge blocks can be employed for precision.
The concept is tied to Newton's third law, emphasizing understanding interaction forces in design.

Load cells convert applied force into electrical signals; commonly used in material testing and weighing scales.
Strain gauges detect deformation in materials, enabling engineers to calculate applied force via elasticity principles.
Pressure sensors measure force by sensing fluid or gas pressure; widely implemented in hydraulic and automotive applications.
Force plates assess ground reaction forces, useful in biomechanics and sports science.

Speed measures how fast an object moves, calculated as distance traveled over time, making it a scalar quantity unlike velocity, which is vectorial.
Speed is crucial in transportation, navigation, surveying, engineering, science, and industrial applications, affecting efficiency and planning.

Instruments for measuring distance include rulers, tape measures, odometers, GPS devices, and surveying tools.
Tape measures are commonly used for direct measurement, featuring graduated markings.

Mass is measured using balance scales, spring scales, digital weighing machines, and techniques like gravimetry and magnetic levitation.
Balance scales compare an unknown mass with known weights, while spring scales measure force based on spring deformation.
Gravitational methods assess mass by measuring gravitational influence, while NMR and interferometry analyze mass indirectly via changes in physical properties.

The range of a measurement instrument indicates the span of values it can accurately measure; a wider range offers versatility whereas a narrow range restricts application.
Resolution is the smallest detectable change in measurement, reflecting the instrument's precision and sensitivity.
For example, an electronic balance with a range of 10 to 100 g and a resolution of 1 mg can detect tiny changes and provide precise measurements for small samples.