Basics of Engineering Metrology

Explore linear measuring instruments, using millimeters to measure distances between surfaces, including calipers, dividers, outside micrometers, digital micrometers, depth micrometers, and scales, with emphasis on accuracy and graduation.

The universal length measuring machine offers metrology with a universal measuring table, enabling floor or fixed setups for measuring dimensions and inspecting tread ring gauge, plug gauges, and snap gauges.

Learn to measure angles in degrees or radians for alignment using bevel protector, protector dial, digital protector, sign bar, and spirit level, with least count and sign principle concepts.

Compare unknown lengths with a standard using comparators in linear measurement, noting that dial indicators are simple mechanical gauges and electronic gauges offer higher accuracy.

Explore temperature measurement devices such as thermocouples with dissimilar wires and junctions, liquid or digital thermometers, and contact versus non-contact sensors, including resistance changes via Wheatstone bridges and thermostats.

Define pressure as force per unit area using newtons and square millimeters. Learn absolute, differential, and atmospheric pressures and explore ring balance and inverted bell devices.

The guideline sets minimum calibration requirements for pressure gauges and estimates measurement uncertainty via direct comparison to reference standards traceable to national standards, with certificates stating expanded uncertainty.

Define pressure as force per unit area and identify the Pascal as the SI unit, then note common units like bar, psi, and standard atmosphere.

Explore the types of pressure gauges used in industry, including absolute, differential, and mechanical gauges. Understand how hydrostatic and mechanical principles convert pressure into readable measurements.

Assess calibration capability through external inspections and functional tests to verify CMC ranges, including precautionary ranges, and note that uncertainty increases when flow and pressure are lowered.

Control conditions for pressure calibration by achieving temperature equalization within 18 to 28 degrees Celsius, keep temperature steady, and record temperature while limiting variation to plus or minus one kelvin.

Explore how gears transmit rotary motion and torque using spur, helical, bevel, spiral bevel, and rack and pinion configurations, with a focus on gear teeth and metrology.

Explore surface metrology and how surface roughness drives quality control and performance prediction in manufacturing. Explore grading and accuracy in measurements, including granite, cast iron, and glass surface plates.

Profile projector measures complex shapes such as gears, games and threads, is easy to use, and serves optical instruments and major machinery manufacturing with projection screen measurements.