What Exactly is Metrology

Metrology is defined by the International Bureau of Weights and Measures (BIPM) as “the science of measurement, embracing both experimental and theoretical determinations at any level of uncertainty in any field of science and technology”.

Metrology is how companies guarantee certain comparisons of global measurement results. As an example, metrology is used to help ensure that the parts in the vehicles we drive are accurately and precisely measured, manufactured, and assembled despite the different manufacturing processes language barriers, and measurement systems (such as US and metric) that are used by the manufacturers.

Metrology also incorporates precision measuring tools like the coordinate measuring machines (CMMs) also the precision measurement sensors.

Globally Standardizing Precision Machined Parts
Today’s global supply chains are using the international measuring standards to help precisely manufacture, distribution, and assembly machined parts through out the world.

All different types of factories from different countries can precisely machine identical parts from CAD or drawings. Each manufacturer’s measuring instrument is calibrated with the same specific thresholds.

These calibrations are designed to ensure that all of the parts created will fit together and work as they were intended to. After the calibration phase is over, the production machines are then set and the quality assurance and controls are confirmed.

Types of Metrology Equipment
A coordinate measuring machine is a system that measures the testing product by combining a probe with the coordinate system to measure the geometric physical points of the product.

In addition to accurate measurements, CMMs have the advantage of providing real-time information on the condition of the manufacturing process to the CMM operator. All global CMMs must comply with the ISO 10360 international measurement standards and can be controlled by either an operator or a computer. Five major types of CMMs are used in today’s metrology:

Cantilever:
This is used primarily for measuring master parts.

Bridge:
Most popular with digitizing and scanning jobs for the mold, stamping, and machining markets.

Gantry:
Used for measuring heavy, large parts such as large dies and molds.

Horizontal Arm:
This is used to measure parts in industries such as defense, aerospace, and appliances.

Portable (PCMM):
Handheld 3D and geometric tolerance and dimensioning measurements which can also be ISO 10360-certified.

Touch-trigger:
Touch-trigger probes are the most commonly used type of probe in metrology because they remove touch bias and can be used with computer control.

There are also two major groupings of probes: contact and non-contact. Contact or tactile probes include:

Hand Probes:
Hand probes are designed to measure curved surfaces, but one must watch out for tactile differences that can be caused by the operators.

Touch-Trigger Probes:
This is the most popular type of probes. It simply removes touch bias and can be used by direct computer control.

Analog Probes:
Use CAS technology to measure irregular shapes and contorted surfaces, like sheet metal. Non-contact probes are used for large, complex geometric, flexible parts. They include:

Laser Probes:
Laser probes are a triangulation with a beam of light designed for high-speed component measurements.

Vision Probes:
Vision Probes are designed for high-speed measurements of small, 2D parts with images taken from a camera.

As previously noted, manufacturers from all over the world need to meet or exceed the set specified tolerances of each item tested so they will fit and work exactly as they were designed to.

This quality assurance covers components manufactured from medical devices to rocket engines and everything in-between. In fact, precision measurement technology is used to ensure the quality assurance of measurements up to one-thousandth of a millimeter.