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Dimensional metrology, also known as industrial metrology, is the application of metrology for quantifying the physical size, form (shape), characteristics, and relational distance from any given feature.
Standardized measurements are essential to technological advancement, and early measurement tools have been found dating back to the dawn of human civilization. [1] Early Mesopotamian and Egyptian metrologists created a set of measurement standards based on body parts known as anthropic units. These ancient systems of measurements utilized fingers, palms, hands, feet, and paces as intervals.
Carpenters and surveyors were some of the first dimensional inspectors, and many specialized units of craftsmen, such as the remen, were worked into a system of unit fractions that allowed for calculations utilizing analytic geometry. Later agricultural measures such as feet, yards, paces, cubits, fathoms, rods, cords, perch, stadia, miles and degrees of the Earth's circumference, many of which are still in use.
Early Egyptian rulers were incremented in units of fingers, palms, and feet based on standardized inscription grids. These grids outlined the standards of measurement as canons of proportion and were made commensurate with Mesopotamian standards based on fingers, hands, and feet. In this system, four palms or three hands measured one foot; ten hands equaled one meter. [2]
These standards were used to measure and define property and were regulated by law for several purposes, such as taxation, infrastructure, and more, such as buildings and fields were adopted by the Greeks, Romans, and Persians as legal standards and became the basis of European standards of measure. [3] They were also used to relate length to area with units such as the khet, setat and aroura; area to volume with units such as the artaba; and space to time with units such as the Egyptian minute of march, which was recorded on travel on a river.
Modern measurement equipment includes hand tools, CMMs (coordinate-measuring machines), machine vision systems, laser trackers, and optical comparators. A CMM is based on CNC technology to automate measurement of Cartesian coordinates using a touch probe, contact scanning probe, or non-contact sensor. Optical comparators are used when physically touching the part is undesirable; components that consist of fragile or mailable materials require measurement using non-contact techniques. Instruments can now build 3D models of a part and its internal features using CT scanning [4] or X-ray imaging. [5]
Measurements are often expressed as a size relative to a theoretically perfect part that has its geometry defined in a print or computer model. A print is a blueprint illustrating the defined geometry of a part and its features. Each feature can have a size, a distance from other features, and an allowed tolerance set for each element. The international language used to describe physical parts is called Geometric Dimensioning and Tolerancing (colloquially known as GD&T). Prints can be hand-drawn or automatically generated by a computer CAD model. However, computer-controlled measurement machines like coordinate measuring machines (CMMs) and vision measuring machines (VMMs) can measure a part relative to a CAD model without the need for a print. Typically, this process is done to reverse engineer components.
Industrial metrology is common in manufacturing quality control systems to help identify errors in component production and ensure proper performance. Blueprints and 3D CAD models are usually made by a mechanical engineer.
Metrology is the scientific study of measurement. It establishes a common understanding of units, crucial in linking human activities. Modern metrology has its roots in the French Revolution's political motivation to standardise units in France when a length standard taken from a natural source was proposed. This led to the creation of the decimal-based metric system in 1795, establishing a set of standards for other types of measurements. Several other countries adopted the metric system between 1795 and 1875; to ensure conformity between the countries, the Bureau International des Poids et Mesures (BIPM) was established by the Metre Convention. This has evolved into the International System of Units (SI) as a result of a resolution at the 11th General Conference on Weights and Measures (CGPM) in 1960.
The cubit is an ancient unit of length based on the distance from the elbow to the tip of the middle finger. It was primarily associated with the Sumerians, Egyptians, and Israelites. The term cubit is found in the Bible regarding Noah's Ark, the Ark of the Covenant, the Tabernacle, and Solomon's Temple. The common cubit was divided into 6 palms × 4 fingers = 24 digits. Royal cubits added a palm for 7 palms × 4 fingers = 28 digits. These lengths typically ranged from 44.4 to 52.92 cm, with an ancient Roman cubit being as long as 120 cm.
The kilogram-force, or kilopond, is a non-standard gravitational metric unit of force. It does not comply with the International System of Units (SI) and is deprecated for most uses. The kilogram-force is equal to the magnitude of the force exerted on one kilogram of mass in a 9.80665 m/s2 gravitational field. That is, it is the weight of a kilogram under standard gravity. Therefore, one kilogram-force is by definition equal to 9.80665 N. Similarly, a gram-force is 9.80665 mN, and a milligram-force is 9.80665 μN.
A unit of length refers to any arbitrarily chosen and accepted reference standard for measurement of length. The most common units in modern use are the metric units, used in every country globally. In the United States the U.S. customary units are also in use. British Imperial units are still used for some purposes in the United Kingdom and some other countries. The metric system is sub-divided into SI and non-SI units.
The pyramid inch is a unit of measure claimed by pyramidologists to have been used in ancient times.
A system of units of measurement, also known as a system of units or system of measurement, is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce. Instances in use include the International System of Units or SI, the British imperial system, and the United States customary system.
The palm is an obsolete anthropic unit of length, originally based on the width of the human palm and then variously standardized. The same name is also used for a second, rather larger unit based on the length of the human hand.
Ancient Mesopotamian units of measurement originated in the loosely organized city-states of Early Dynastic Sumer. Each city, kingdom and trade guild had its own standards until the formation of the Akkadian Empire when Sargon of Akkad issued a common standard. This standard was improved by Naram-Sin, but fell into disuse after the Akkadian Empire dissolved. The standard of Naram-Sin was readopted in the Ur III period by the Nanše Hymn which reduced a plethora of multiple standards to a few agreed upon common groupings. Successors to Sumerian civilization including the Babylonians, Assyrians, and Persians continued to use these groupings. Akkado-Sumerian metrology has been reconstructed by applying statistical methods to compare Sumerian architecture, architectural plans, and issued official standards such as Statue B of Gudea and the bronze cubit of Nippur.
A coordinate measuring machine (CMM) is a device that measures the geometry of physical objects by sensing discrete points on the surface of the object with a probe. Various types of probes are used in CMMs, the most common being mechanical and laser sensors, though optical and white light sensor do exist. Depending on the machine, the probe position may be manually controlled by an operator or it may be computer controlled. CMMs typically specify a probe's position in terms of its displacement from a reference position in a three-dimensional Cartesian coordinate system. In addition to moving the probe along the X, Y, and Z axes, many machines also allow the probe angle to be controlled to allow measurement of surfaces that would otherwise be unreachable.
The earliest recorded systems of weights and measures originate in the 3rd or 4th millennium BC. Even the very earliest civilizations needed measurement for purposes of agriculture, construction and trade. Early standard units might only have applied to a single community or small region, with every area developing its own standards for lengths, areas, volumes and masses. Often such systems were closely tied to one field of use, so that volume measures used, for example, for dry grains were unrelated to those for liquids, with neither bearing any particular relationship to units of length used for measuring cloth or land. With development of manufacturing technologies, and the growing importance of trade between communities and ultimately across the Earth, standardized weights and measures became critical. Starting in the 18th century, modernized, simplified and uniform systems of weights and measures were developed, with the fundamental units defined by ever more precise methods in the science of metrology. The discovery and application of electricity was one factor motivating the development of standardized internationally applicable units.
Traditional Japanese units of measurement or the shakkanhō (尺貫法) is the traditional system of measurement used by the people of the Japanese archipelago. It is largely based on the Chinese system, which spread to Japan and the rest of the Sinosphere in antiquity. It has remained mostly unaltered since the adoption of the measures of the Tang dynasty in 701. Following the 1868 Meiji Restoration, Imperial Japan adopted the metric system and defined the traditional units in metric terms on the basis of a prototype metre and kilogram. The present values of most Korean and Taiwanese units of measurement derive from these values as well.
ASME Y14.41 is a standard published by American Society of Mechanical Engineers (ASME) which establishes requirements and reference documents applicable to the preparation and revision of digital product definition data, which pertains to CAD software and those who use CAD software to create the product definition within the 3D model. ASME issued the first version of this industrial standard on Aug 15, 2003 as ASME Y14.41-2003. It was immediately adopted by several industrial organizations, as well as the Department of Defense (DOD). The latest revision of ASME Y14.41 was issued on Jan 23, 2019 as ASME Y14.41-2019.
Some approaches in the branch of historic metrology are highly speculative and can be qualified as pseudoscience.
STEP-NC is a machine tool control language that extends the ISO 10303 STEP standards with the machining model in ISO 14649, adding geometric dimension and tolerance data for inspection, and the STEP PDM model for integration into the wider enterprise. The combined result has been standardized as ISO 10303-238.
A unit of measurement is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can be expressed as a multiple of the unit of measurement.
Industrial computed tomography (CT) scanning is any computer-aided tomographic process, usually X-ray computed tomography, that uses irradiation to produce three-dimensional internal and external representations of a scanned object. Industrial CT scanning has been used in many areas of industry for internal inspection of components. Some of the key uses for industrial CT scanning have been flaw detection, failure analysis, metrology, assembly analysis and reverse engineering applications. Just as in medical imaging, industrial imaging includes both nontomographic radiography and computed tomographic radiography.
In metrology, a standard is an object, system, or experiment that bears a defined relationship to a unit of measurement of a physical quantity. Standards are the fundamental reference for a system of weights and measures, against which all other measuring devices are compared. Historical standards for length, volume, and mass were defined by many different authorities, which resulted in confusion and inaccuracy of measurements. Modern measurements are defined in relationship to internationally standardized reference objects, which are used under carefully controlled laboratory conditions to define the units of length, mass, electrical potential, and other physical quantities.
Length measurement, distance measurement, or range measurement (ranging) refers to the many ways in which length, distance, or range can be measured. The most commonly used approaches are the rulers, followed by transit-time methods and the interferometer methods based upon the speed of light.