Engineering drawing symbols - AbsoluteAstronomy.com

Engineering drawing abbreviations and symbols are used to communicate and detail the characteristics of an engineering drawing

Engineering drawing

An engineering drawing, a type of technical drawing, is used to fully and clearly define requirements for engineered items.Engineering drawing produces engineering drawings . More than just the drawing of pictures, it is also a language—a graphical language that communicates ideas and information...

Abbreviation/symbol	Definition	Description
	across corners	Commonly used when measuring the corners of a hex drive, such as a hex nut.
	across flats	Commonly used when measuring the corners of a hex drive, such as a hex nut.
or	aluminium Aluminium Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
	alloy Alloy An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
	American
	Aerospace Material Standards	Standards in materials science and engineering maintained by SAE International SAE International SAE International is an organization for engineering professionals in the aerospace, automotive, and commercial vehicle industries. The Society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others.SAE... and widely used in the aerospace manufacturing Aerospace manufacturer An aerospace manufacturer is a company or individual involved in the various aspects of designing, building, testing, selling, and maintaining aircraft, aircraft parts, missiles, rockets, and/or spacecraft.... industries.
	Army-Navy	A prefix for standard hardware (catalog hardware) ID numbers. Came from the era of circa 1890s-1945, when the U.S. Army United States Army The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services... and Navy United States Navy The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S... were leading the way on product standardization Standardization Standardization is the process of developing and implementing technical standards.The goals of standardization can be to help with independence of single suppliers , compatibility, interoperability, safety, repeatability, or quality.... for logistics Logistics Logistics is the management of the flow of goods between the point of origin and the point of destination in order to meet the requirements of customers or corporations. Logistics involves the integration of information, transportation, inventory, warehousing, material handling, and packaging, and... improvement, yielding the United States Military Standards system. Today industry and ISO also do a lot of this standardization specification, freeing the U.S. DoD and military to do less of it (as explained at United States Military Standard > Origins and evolution), although many MIL standards are still current. (See also MS- and NAS.)
	anneal Annealing (metallurgy) Annealing, in metallurgy and materials science, is a heat treatment wherein a material is altered, causing changes in its properties such as strength and hardness. It is a process that produces conditions by heating to above the recrystallization temperature, maintaining a suitable temperature, and... , annealed
	American National Standards Institute American National Standards Institute The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international...	And the many standards that it issues, for example, ANSI Z87.1.
	approximately
	approved product supplier, approved vendor, approved-product-supplier list, approved-vendor list	When only certain companies are approved by the CDA to manufacture the product (that is, to make what the drawing depicts/defines), they are called by names such as "approved supplier", "approved product supplier", "approved vendor", or "approved product vendor". The list of such companies (which usually changes over time) is called an APSL, AVL, or similar names. Vetting the companies on this list requires the CDA to audit Audit The general definition of an audit is an evaluation of a person, organization, system, process, enterprise, project or product. The term most commonly refers to audits in accounting, but similar concepts also exist in project management, quality management, and energy conservation.- Accounting... (and possibly periodically re-audit) the companies, which incurs an overhead Overhead (business) In business, overhead or overhead expense refers to an ongoing expense of operating a business... expense for the CDA. Therefore, smaller companies will often cite larger companies' lists in order to avoid the cost of duplicating the effort.
	Aerospace Standards	Standards maintained by SAE International SAE International SAE International is an organization for engineering professionals in the aerospace, automotive, and commercial vehicle industries. The Society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others.SAE... and widely used in the aerospace manufacturing Aerospace manufacturer An aerospace manufacturer is a company or individual involved in the various aspects of designing, building, testing, selling, and maintaining aircraft, aircraft parts, missiles, rockets, and/or spacecraft.... industries. Standard aerospace hardware sometimes has the AS- prefix in the catalog numbers.
	American Society of Mechanical Engineers American Society of Mechanical Engineers The American Society of Mechanical Engineers is a professional body, specifically an engineering society, focused on mechanical engineering....	And the many standards that it issues, for example, ASME Y14.5.
	assembly	referring to an assembly of parts rather than just one (sub)part ("piece part", "detail part").
	Formerly the American Society for Testing and Materials; now ASTM International ASTM International ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...	Maintains technical standards, especially regarding materials science and engineering and metrology Metrology Metrology is the science of measurement. Metrology includes all theoretical and practical aspects of measurement. The word comes from Greek μέτρον , "measure" + "λόγος" , amongst others meaning "speech, oration, discourse, quote, study, calculation, reason"... .
	average Average In mathematics, an average, or central tendency of a data set is a measure of the "middle" value of the data set. Average is one form of central tendency. Not all central tendencies should be considered definitions of average....
	bolt circle
	bronze Bronze Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and brittle, and it was particularly significant in antiquity, so much so that the Bronze Age was named after the metal...
	computer-aided design Computer-aided design Computer-aided design , also known as computer-aided design and drafting , is the use of computer technology for the process of design and design-documentation. Computer Aided Drafting describes the process of drafting with a computer... , computer-aided drafting; cadmium [plating]
	Commercial and Government Entity Commercial and Government Entity The Commercial And Government Entity Code, or CAGE Code, is a unique identifier assigned to suppliers to various government or defense agencies, as well as to government agencies themselves and also various organizations... [code]	A CAGE code is a unique identifier Unique identifier With reference to a given set of objects, a unique identifier is any identifier which is guaranteed to be unique among all identifiers used for those objects and for a specific purpose... to label an entity (that is, a specific government agency or corporation at a specific site) that is a CDA, ODA, or MFR of the part defined by the drawing. One corporation can have many CAGE codes, as can one government, because each division, department, and site (campus) can have its own CAGE code. The same CAGE code can change owners over the years. For example, a CAGE code that formerly referred to a certain Martin Marietta Martin Marietta Martin Marietta Corporation was an American company founded in 1961 through the merger of The Martin Company and American-Marietta Corporation. The combined company became a leader in chemicals, aerospace, and electronics. In 1995, it merged with Lockheed Corporation to form Lockheed Martin. The... site will now refer to Lockheed Martin Lockheed Martin Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area.... at that same site (although the buildings may have been replaced and the signage may say different names).
	centre-to-centre; on centres	Defines centre-to-centre distance of two features, such as two holes.
	current design activity	The CDA is the entity (whether it be a corporation Corporation A corporation is created under the laws of a state as a separate legal entity that has privileges and liabilities that are distinct from those of its members. There are many different forms of corporations, most of which are used to conduct business. Early corporations were established by charter... , a unit of a national military Military A military is an organization authorized by its greater society to use lethal force, usually including use of weapons, in defending its country by combating actual or perceived threats. The military may have additional functions of use to its greater society, such as advancing a political agenda e.g... or ministry of defence Ministry of Defence In states where the government is divided into ministries, the Ministry of Defence may refer to that part of the government responsible for matters of defence, usually including all branches of the military and is usually controlled by a Defence minister or minister of defence.-List of Defence... , or another civilian government agency) that currently has design authority over the part design (definition). It may be the entity who first designed the part (that is, the ODA), but today it is also likely to be a designated successor entity, owing to mergers and acquisitions Mergers and acquisitions Mergers and acquisitions refers to the aspect of corporate strategy, corporate finance and management dealing with the buying, selling, dividing and combining of different companies and similar entities that can help an enterprise grow rapidly in its sector or location of origin, or a new field or... (M&A) activity (e.g., ODA company was bought by CDA company); contract letting (e.g., an Army engineering department ODA turns over the design activity to the prime contractor that makes most or all of the parts, turning that contractor into the new CDA); privatization Privatization Privatization is the incidence or process of transferring ownership of a business, enterprise, agency or public service from the public sector to the private sector or to private non-profit organizations... (e.g., a government privatizes the design and manufacture of materiel Materiel Materiel is a term used in English to refer to the equipment and supplies in military and commercial supply chain management.... , and a state arsenal Arsenal An arsenal is a place where arms and ammunition are made, maintained and repaired, stored, issued to authorized users, or any combination of those... [state armory Armory Armory or armoury may mean:Armory , a military location used for the storage of arms and ammunitionArmory , the study of coats of armsArmory , a Marvel Comics character... ] ODA transfers design authority to a private armory Armory Armory or armoury may mean:Armory , a military location used for the storage of arms and ammunitionArmory , the study of coats of armsArmory , a Marvel Comics character... [defense contractor Defense contractor A defense contractor is a business organization or individual that provides products or services to a military department of a government. Products typically include military aircraft, ships, vehicles, weaponry, and electronic systems... ] ODA); or patent licensing (e.g., a patent-holding inventor [ODA] licenses one or several companies to manufacture products using his intellectual property, in which case the "same" part could end up with multiple design authorities, although they may not be considered the official/nominal CDA).
CERT or cert	certification Certification Certification refers to the confirmation of certain characteristics of an object, person, or organization. This confirmation is often, but not always, provided by some form of external review, education, assessment, or audit...	For example, certification of metallurgical content and processes
CG	centerless ground, centerless grinding Centerless grinding Centerless grinding is a method of material removal through grinding, similar to centered grinding except for the absence of the spindle. It has high throughput, i.e. a large number of parts can be manufactured in a short time....
or ℄	center line	Center line of a feature
	Center mark	Defines the center of a circle or partial circle.
	chamfer Chamfer A chamfer is a beveled edge connecting two surfaces. If the surfaces are at right angles, the chamfer will typically be symmetrical at 45 degrees. A fillet is the rounding off of an interior corner. A rounding of an exterior corner is called a "round" or a "radius"."Chamfer" is a term commonly...
	computer numerical control Numerical control Numerical control refers to the automation of machine tools that are operated by abstractly programmed commands encoded on a storage medium, as opposed to controlled manually via handwheels or levers, or mechanically automated via cams alone...
	controlled radius	Radius of an arc or circle, with no flats or reversals. Specified when the form of the radius must be controlled more strictly than "just falling within the dimensional tolerance zone".
	corrosion-resistant [steel]	Largely synonymous with stainless steel Stainless steel In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass.... , unless specific grades, specs, and distinctions are made on the drawing. Some people treat CRES as a subset of the stainless steels.
	cold rolled steel; on centres	Defines centre-to-centre distance of two features, such as two holes.
or	counterbore Counterbore A counterbore can refer to a cylindrical flat-bottomed hole, which enlarges another hole, or the tool used to create that feature. A spot face is a very shallow counterbore...
or	countersink Countersink A countersink is a conical hole cut into a manufactured object, or the cutter used to cut such a hole. A common usage is to allow the head of a countersunk bolt or screw, when placed in the hole, to sit flush with or below the surface of the surrounding material...
	depth, deep, down	Defines the depth of a feature.
or ⌀ or	diameter Diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...	Diameter of a circle. In a feature control frame (FCF), the ⌀ symbol tells you that the tolerance zone for the geometric tolerance is cylindrical Cylinder (geometry) A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder... .
	dimension, dimensioning
, DOD	[U.S.] Department of Defense	See also MoD.
	digital product definition	A synonym of MBD.
, ECO, ECN	engineering order	An order from the engineering department (to be followed by the production department or vendor) overriding/superseding a detail on the drawing, which gets superseded with revised information. Also called by various other names, such as engineering change order (ECO), engineering change notice (ECN), drawing change notice (DCN), and so on. See also REV.
	equal, equally	For example, "⌀10 4X EQ SPACED ON BC" means "drill four holes of 10mm diameter equally spaced around the bolt circle."
	feature control frame	The rectangular box (with several cells) that conveys geometric tolerances in GD&T. It typically tells you what sort of geometric condition (e.g., parallel, perpendicular, round, concentric), followed by what size (and maybe shape) the tolerance zone is, and finally which datums it relates to, the order of gaging against them, and what material condition applies to them (LMC, MMC, or RFS). A diameter symbol (⌀) tells you that the zone for the geometric tolerance is cylindrical Cylinder (geometry) A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder... .
or F/D	field of the drawing	The [main] field of the drawing, as opposed to other areas of it, such as the parts list (P/L), general notes (G/N), title block (T/B), rev block (R/B), bill of materials (B/M or BoM or BOM), or list of materials (L/M). Rationales for drawing changes that are noted in the rev block often use these abbreviations for brevity (e.g., "DIM 14 was 12; added default TOL info to T/B; added leader lines to F/D; added alternate hardware IDs to P/L; added alternate alloy to L/M").
	flag note, flagnote	A note that is called out in specific spots in the field of the drawing. It is numbered with a stylized flag symbol surrounding the number. A general note applies generally and is not called out with flags.
	flag note, flagnote	A note that is called out in specific spots in the field of the drawing. It is numbered with a stylized flag symbol surrounding the number. A general note applies generally and is not called out with flags.
	feature of size	A type of physical feature on a part. An FoS is a feature that can have size associated with it, usually involving the opposition of two surfaces (e.g., the two diametrically opposite sides of a hole wall; the two opposite walls of a slot or flange). Features of size (FoSs) in reality always have actual sizes and forms that differ from their theoretical size and form; the purpose of tolerancing is to define whether the difference is acceptable or not. Thus material condition (LMC, MMC, somewhere in between, or RFS) is important in GD&T. ) A given geometric tolerance may be defined in relation to a certain FoS datum being at LMC or at MMC.
	geometric dimensioning and tolerancing Geometric dimensioning and tolerancing Geometric dimensioning and tolerancing is a system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models for explicitly describing nominal geometry and its allowable variation...	A standardized language for defining and communicating dimensions and tolerances.
	general note(s)	Most engineering drawings have a notes list, which includes both general notes and flag notes.
	hot rolled steel
	heat treat, heat treatment Heat treatment Heat treating is a group of industrial and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass...
or H/T or HT	hardened and tempered	A form of heat treatment Heat treatment Heat treating is a group of industrial and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass... in which the metal is first hardened Hardening (metallurgy) Hardening is a metallurgical and metalworking process used to increase the hardness of a metal. The hardness of a metal is directly proportional to the uniaxial yield stress at the location of the imposed strain... and then tempered Tempering Tempering is a heat treatment technique for metals, alloys and glass. In steels, tempering is done to "toughen" the metal by transforming brittle martensite or bainite into a combination of ferrite and cementite or sometimes Tempered martensite... . Compare N&T.
	inner diameter; identity, identification number
	International Organization for Standardization International Organization for Standardization The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...	And the many standards that it specifies, for example, ISO 10303 ISO 10303 ISO 10303 is an ISO standard for the computer-interpretable representation and exchange of product manufacturing information. Its official title is: Automation systems and integration — Product data representation and exchange...
	kilopounds per square inch, that is, thousands of pounds per square inch Pounds per square inch The pound per square inch or, more accurately, pound-force per square inch is a unit of pressure or of stress based on avoirdupois units...	A common non-SI International System of Units The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups of units... measurement scale for ultimate tensile strength, that is, the number of units of tensile force that a material can endure per unit of cross-sectional area before breaking.
	machine
	least material condition	A material condition in GD&T. Means that a feature of size (FoS) is at the limit of its size tolerance in the direction that leaves the least material left on the part. Thus an internal feature of size (e.g., a hole) at its biggest diameter, or an external feature of size (e.g., a flange Flange A flange is an external or internal ridge, or rim , for strength, as the flange of an iron beam such as an I-beam or a T-beam; or for attachment to another object, as the flange on the end of a pipe, steam cylinder, etc., or on the lens mount of a camera; or for a flange of a rail car or tram wheel... ) at its smallest thickness. The GD&T symbol for LMC is a circled L. (See also MMC and RFS.) A given geometric tolerance may be defined in relation to a certain FoS datum being at LMC or at MMC.
	maximum Maxima and minima In mathematics, the maximum and minimum of a function, known collectively as extrema , are the largest and smallest value that the function takes at a point either within a given neighborhood or on the function domain in its entirety .More generally, the...
	model-based definition	Definition of the part via a 3D CAD Computer-aided design Computer-aided design , also known as computer-aided design and drafting , is the use of computer technology for the process of design and design-documentation. Computer Aided Drafting describes the process of drafting with a computer... model rather than via a 2D engineering drawing. Drawings may be printed (plotted) from the model for reference use, but the model remains the governing legal instrument Legal instrument Legal instrument is a legal term of art that is used for any formally executed written document that can be formally attributed to its author, records and formally expresses a legally enforceable act, process, or contractual duty, obligation, or right, and therefore evidences that act, process, or... .
	manufactured
	manufacturing
	manufacturer	May be the same entity as the CDA or ODA, or may not be.
	[U.S.] Military	A prefix for the names of various United States Military Standards and Specifications, for example, MIL-STD-, MIL-SPEC-, MIL-DTL-, MIL-PRF-, MIL-A-, MIL-C-, MIL-S-*, MIL-STD-1913, MIL-STD-1397 MIL-STD-1397 MIL-STD-1397 standard was issued by the United States Department of Defense to define "the requirements for the physical, functional and electrical characteristics of a standard I/O data interface for digital data." The MIL-STD-1397 classification types A, B and D apply specifically to the Naval... .
	minimum Maxima and minima In mathematics, the maximum and minimum of a function, known collectively as extrema , are the largest and smallest value that the function takes at a point either within a given neighborhood or on the function domain in its entirety .More generally, the... ; minute Minute A minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units... s
	maximum material condition	A material condition in GD&T. Means that a feature of size (FoS) is at the limit of its size tolerance in the direction that leaves the most material left on the part. Thus an internal feature of size (e.g., a hole) at its smallest diameter, or an external feature of size (e.g., a flange Flange A flange is an external or internal ridge, or rim , for strength, as the flange of an iron beam such as an I-beam or a T-beam; or for attachment to another object, as the flange on the end of a pipe, steam cylinder, etc., or on the lens mount of a camera; or for a flange of a rail car or tram wheel... ) at its biggest thickness. The GD&T symbol for MMC is a circled M. (See also LMC and RFS.) A given geometric tolerance may be defined in relation to a certain FoS datum being at LMC or at MMC.
, MOD	Ministry of Defence [U.K. and others]	See also DoD.
	[U.S.] Military Standard	Standards established by the U.S. military and widely used in the aerospace manufacturing Aerospace manufacturer An aerospace manufacturer is a company or individual involved in the various aspects of designing, building, testing, selling, and maintaining aircraft, aircraft parts, missiles, rockets, and/or spacecraft.... (military and civil) and other defense Defense contractor A defense contractor is a business organization or individual that provides products or services to a military department of a government. Products typically include military aircraft, ships, vehicles, weaponry, and electronic systems... industries. Standard hardware sometimes uses the MS- prefix in the catalog numbers. (See also AN- and NAS.)
	nominal Real versus nominal value In economics, nominal value refers to a value expressed in money terms in a given year or series of years. By contrast, real value adjusts nominal value to remove effects of price changes over time...
or NORMD	normalized	referring to normalization, a stress-relieving heat treatment. See also HT TR.
	National Aerospace Standards	Standards maintained by SAE International SAE International SAE International is an organization for engineering professionals in the aerospace, automotive, and commercial vehicle industries. The Society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others.SAE... and widely used in the aerospace manufacturing Aerospace manufacturer An aerospace manufacturer is a company or individual involved in the various aspects of designing, building, testing, selling, and maintaining aircraft, aircraft parts, missiles, rockets, and/or spacecraft.... industries. The "National" formerly implicitly referenced the USA, but today NAS and other standards are used globally. Standard hardware for aerospace work sometimes uses the NAS- prefix in the catalog numbers. (See also AN- and MS-.)
	National Coarse; numerical control Numerical control Numerical control refers to the automation of machine tools that are operated by abstractly programmed commands encoded on a storage medium, as opposed to controlled manually via handwheels or levers, or mechanically automated via cams alone...	The [U.S.] National Coarse series of pre-1949 corresponds today to the Unified National Coarse (UNC) of the Unified Thread Standard Unified Thread Standard The Unified Thread Standard defines a standard thread form and series—along with allowances, tolerances, and designations—for screw threads commonly used in the United States and Canada... .
	National Fine	The [U.S.] National Fine series of pre-1949 corresponds today to the Unified National Fine (UNF) of the Unified Thread Standard Unified Thread Standard The Unified Thread Standard defines a standard thread form and series—along with allowances, tolerances, and designations—for screw threads commonly used in the United States and Canada... .
	notes list	A list of notes that appears somewhere on the drawing, often in the upper left corner.
or N/T or NT	normalized and tempered	A form of heat treatment Heat treatment Heat treating is a group of industrial and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass... in which the metal is first normalized (stress-relieved) and then tempered Tempering Tempering is a heat treatment technique for metals, alloys and glass. In steels, tempering is done to "toughen" the metal by transforming brittle martensite or bainite into a combination of ferrite and cementite or sometimes Tempered martensite... . Compare H&T.
	outer diameter
	original design activity	The entity that originally designed a part. Compare to CDA, the entity that currently has design authority over the part design (definition).
, PDMS	product data management, product data manager [app], product data management system [app]	A database(s) and related application(s) that facilitate all aspects of managing data files—e.g., TDPs, TDP versions, drawings, model datasets, specs, addenda, certs, memoranda, EOs, ECOs, DCNs, RFQs, quotes, POs, e-mails, faxes, photos, word processor documents, spreadsheets. See also PLM.
	precipitation hardening, precipitation-hardened
	phosphor bronze Phosphor bronze Phosphor bronze is an alloy of copper with 3.5 to 10% of tin and a significant phosphorus content of up to 1%. The phosphorus is added as deoxidizing agent during melting....
or P/L	parts list	A list, usually tabular and often on the drawing (if not accompanying the drawing on a separate sheet), listing the parts needed in an assembly, including subparts, standard parts, and hardware.
	product lifecycle management Product lifecycle management In industry, product lifecycle management is the process of managing the entire lifecycle of a product from its conception, through design and manufacture, to service and disposal... ; plant lifecycle management Plant lifecycle management Plant lifecycle management is the process of managing an industrial facility's data and information throughout its lifetime. Plant lifecycle management differs from product lifecycle management by its primary focus on the integration of logical, physical and technical plant data in a combined...	See also PDM.
or P/N	part number Part number A part number is an identifier of a particular part design used in a particular industry. Its purpose is to simplify referencing to that part...
or TSC	point of intersection or theoretical sharp corner	A point that makes the layout Layout Layout may refer to:* Page layout Comprehensive layout In computer graphics, another name for a scene used to render 2D/3D graphics or animation* Layout , software that automatically calculates the positions of objects... of the part easier. It is usually the intersection Intersection Intersection has various meanings in different contexts:In mathematics and geometryIntersection , the set of elements common to some collection of sets.Line-line intersectionLine-plane intersection*Line–sphere intersection... of the tangent Tangent In geometry, the tangent line to a plane curve at a given point is the straight line that "just touches" the curve at that point. More precisely, a straight line is said to be a tangent of a curve at a point on the curve if the line passes through the point on the curve and has slope where f... lines of a curve Curve In mathematics, a curve is, generally speaking, an object similar to a line but which is not required to be straight... .
	pounds per square inch Pounds per square inch The pound per square inch or, more accurately, pound-force per square inch is a unit of pressure or of stress based on avoirdupois units...	A unit of measurement for pressure. See also KSI.
	polytetrafluoroethylene Polytetrafluoroethylene Polytetrafluoroethylene is a synthetic fluoropolymer of tetrafluoroethylene that finds numerous applications. PTFE is most well known by the DuPont brand name Teflon....	Also well known by the brand name Teflon.
	radius	Radius of an arc or circle. Flats and reversals (falling within the dimensional tolerance zone) are tolerated unless "CR" (controlled radius) is explicitly specified.
or ( )	reference	The dimension is only given for reference and should not be used for production or inspection. The dimension may also be surrounded by parentheses to signify a reference dimension.
or REQ'D	required	For example, "4 REQD" written next to a fastener means that four of those fasteners are required for the assembly.
	revision	Engineering drawings and material or process specifications are often revised; the usual revision control Revision control Revision control, also known as version control and source control , is the management of changes to documents, programs, and other information stored as computer files. It is most commonly used in software development, where a team of people may change the same files... convention is to label the versions A, B, C, D, etc; a revision block (rev block) is a tabular area on the drawing (typically in the upper right corner) that lists the revision letters, a brief description of the changes and reasons, and approval initials and dates. In the days of manual drafting, redrawing was expensive, so engineering orders (EOs, ECOs, DCNs, ECNs) were not always incorporated into a next-letter revision. They thus accompany the drawing as part of the TDP. With the dissemination of software usage (CAD, CAM, PDMSs), revision control is often better handled nowadays, in competent hands at least.
	regardless of feature size	A material condition (or more precisely, freedom from such) in GD&T. Means that a given geometric tolerance is true in relation to a certain datum regardless of its actual size (LMC ≤ actual size ≤ MMC).
or RT	rough turn, rough turned	Turned on a lathe but not finished to a final machined dimension and roughness. Can apply to bar stock Bar stock Bar stock, also colloquially known as billet, is a common form of raw purified metal, used by industry to manufacture metal parts and products.... or to parts in-process.
	release to production	The issuance of a drawing from the engineering/design activity to the production activity. In other words, the event when a draft becomes a completed, official document. A stamp on the drawing saying "ISSUED" documents that RTP has occurred.
	socket head cap screw	A cap screw with a socket head (usually implying a hex socket, driven with a hex key Hex key A hex key, Allen key, or Allen wrench is a tool of hexagonal cross-section used to drive bolts and screws that have a hexagonal socket in the head .- Nomenclature :... .
	socket head set screw	A set screw Set screw A set screw is a type of screw generally used to secure an object within or against another object. The most common examples are securing a pulley or gear to a shaft. Set screws are most often headless , meaning that the screw is fully threaded and has no head projecting past the major diameter of... with a socket head (usually implying a hex socket, driven with a hex key Hex key A hex key, Allen key, or Allen wrench is a tool of hexagonal cross-section used to drive bolts and screws that have a hexagonal socket in the head .- Nomenclature :... .
	Système international [d'unités] [International System of Units International System of Units The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups of units... ]	The metric system in its current form (latest standards).
	Formerly the Society of Automotive Engineers; now SAE International SAE International SAE International is an organization for engineering professionals in the aerospace, automotive, and commercial vehicle industries. The Society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others.SAE...	And the many standards that it issues, for example, the SAE AMS and SAE AS standards series.
or S/N	serial number Serial number A serial number is a unique number assigned for identification which varies from its successor or predecessor by a fixed discrete integer value...
	solution anneal Annealing (metallurgy) Annealing, in metallurgy and materials science, is a heat treatment wherein a material is altered, causing changes in its properties such as strength and hardness. It is a process that produces conditions by heating to above the recrystallization temperature, maintaining a suitable temperature, and... , solution annealed
	specification Specification (technical standard) A specification is an explicit set of requirements to be satisfied by a material, product, or service. Should a material, product or service fail to meet one or more of the applicable specifications, it may be referred to as being out of specification;the abbreviation OOS may also be used...
	Spot facing
	spherical radius	Radius of a sphere or spherical segment.
	stainless steel Stainless steel In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
	Standard
	Standard for the Exchange of Product Model Data	A standard format defined by ISO 10303 ISO 10303 ISO 10303 is an ISO standard for the computer-interpretable representation and exchange of product manufacturing information. Its official title is: Automation systems and integration — Product data representation and exchange... for MBD data generation, storage, and exchange.
	solution treated and aged
	steel Steel Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
	stock	A nominal dimension for the stock material, such as bar stock Bar stock Bar stock, also colloquially known as billet, is a common form of raw purified metal, used by industry to manufacture metal parts and products....
	Tapped hole	Usually implies drilling Drilling Drilling is a cutting process that uses a drill bit to cut or enlarge a hole in solid materials. The drill bit is a multipoint, end cutting tool... a hole if the hole does not already exist.
	title block	An area of the drawing, almost always at the bottom right, that contains the title of the drawing and other key information. Typical fields in the title block include the drawing title (usually the part name); drawing number (usually the part number); names and/or ID numbers relating to who designed and/or manufactures the part (which involves some complication because design and manufacturing entities for a given part number often change over the years due to mergers and acquisitions Mergers and acquisitions Mergers and acquisitions refers to the aspect of corporate strategy, corporate finance and management dealing with the buying, selling, dividing and combining of different companies and similar entities that can help an enterprise grow rapidly in its sector or location of origin, or a new field or... , contract letting, privatization Privatization Privatization is the incidence or process of transferring ownership of a business, enterprise, agency or public service from the public sector to the private sector or to private non-profit organizations... , and the buying and selling of intellectual property—see CDA and ODA); company name (see previous comment); initials/signatures of the original draftsman (as wells as the original checker and tracer in the days of manual drafting); initials/signatures of approving managers (issuance/release-to-production information); cross-references to other documents; default tolerancing values for dimensions, geometry, and surface roughness; raw-material info (if not given in a separate list/bill of materials); and access control Access control Access control refers to exerting control over who can interact with a resource. Often but not always, this involves an authority, who does the controlling. The resource can be a given building, group of buildings, or computer-based information system... information (information about who is authorized to possess, view, or share copies of the information encoded by the drawing, e.g., classification Classified information Classified information is sensitive information to which access is restricted by law or regulation to particular groups of persons. A formal security clearance is required to handle classified documents or access classified data. The clearance process requires a satisfactory background investigation... notices, copyright notices, patent Patent A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention.... numbers). Drawing revision (versioning) information is not always included in the title block because it often appears in a separate revisions block.
	technical data package	The complete package of information that defines a part, of which the drawing itself is often only a subset. It also includes engineering orders (drawing change notices), 3D model datasets, data tables, memoranda, and any special conditions called out by the purchase order or the companies' terms-and-conditions documents.
	Through	Usually applied to a hole dimension to signify that the hole extends through the wall thickness; in other words, a through hole rather than a blind hole
	Through all	Similar to THRU except the hole extends through the whole workpiece. This is usually used if there are multiple openings that the feature extends through.
	titanium Titanium Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
	titanium nitride Titanium nitride Titanium nitride is an extremely hard ceramic material, often used as a coating on titanium alloys, steel, carbide, and aluminium components to improve the substrate's surface properties.... [plating]
	total indicated runout; total indicator reading	For measurements of eccentricity and other deviations from nominal geometry
	tolerance, tolerancing
	Typical	Other features share the same characteristic
	Unified National Coarse	a subset series of the Unified Thread Standard Unified Thread Standard The Unified Thread Standard defines a standard thread form and series—along with allowances, tolerances, and designations—for screw threads commonly used in the United States and Canada...
	Unified National Fine	a subset series of the Unified Thread Standard Unified Thread Standard The Unified Thread Standard defines a standard thread form and series—along with allowances, tolerances, and designations—for screw threads commonly used in the United States and Canada...
	ultimate tensile strength; Unified Thread Standard Unified Thread Standard The Unified Thread Standard defines a standard thread form and series—along with allowances, tolerances, and designations—for screw threads commonly used in the United States and Canada...
or ( )	number of places—for example, 8X or (8)	When a dimension is used in multiple places either of these prefixes can be added to the dimension to define how many times this dimension is used. This example signifies eight places. (Note on character encoding Character encoding A character encoding system consists of a code that pairs each character from a given repertoire with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the transmission of data through telecommunication networks or storage of text in... : Although in typography (including Unicode Unicode Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems... ) the letter X and the multiplication sign (×) are distinct character Character (computing) In computer and machine-based telecommunications terminology, a character is a unit of information that roughly corresponds to a grapheme, grapheme-like unit, or symbol, such as in an alphabet or syllabary in the written form of a natural language.... s with differing glyph Glyph A glyph is an element of writing: an individual mark on a written medium that contributes to the meaning of what is written. A glyph is made up of one or more graphemes.... s, it is a longstanding tradition in engineering drawing that the letter X is interchangeable with the multi sign, unless otherwise specified by the CAx CAx Computer-aided technologies is a broad term that means the use of computer technology to aid in the design, analysis, and manufacture of products.... systems used.)
	—	Calls out the drawing standard that this drawing is following. For example, ASME Y14.5 and Y14.100 are commonly used standards that define all of the symbols and drafting conventions used.

See also