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Engineering drawing shares some traits with artistic drawing in that both create pictures.
But whereas the purpose of artistic drawing is to convey emotion or artistic sensitivity in some way subjective impressionsthe purpose of engineering drawing is to convey information objective facts.
Engineering drawing uses an extensive set of conventions to convey information very precisely, with very little ambiguity. Relationship to other technical drawing types[ edit ] The process of producing engineering drawings, and the skill of producing those, is often referred to as technical drawing or drafting draughting although technical drawings are also required for disciplines that would not ordinarily be thought of as parts of engineering such as architecturelandscapingcabinet makingand garment-making.
Persons employed in the trade of producing engineering drawings were called draftsmen or draughtsmen in the past. Although these terms are still in use, the not -gender-specific terms draftsperson and drafter are now more common.
Cascading of conventions by speciality[ edit ] The various fields share many common conventions of drawing, while also having some field-specific conventions.
P scales writing app grida example, even within metalworking, there are some process-specific conventions to be learned— castingmachiningfabricatingand assembly all have some special drawing conventions, and within fabrication there is further division, including weldingrivetingpipefittingand erecting.
Each of these trades has some details that only specialists will have memorized. Legal instruments[ edit ] An engineering drawing is a legal document that is, a legal instrumentbecause it communicates all the needed information about "what is wanted" to the people who will expend resources turning the idea into a reality.
It is thus a part of a contract ; the purchase order and the drawing together, as well as any ancillary documents engineering change orders [ECOs], called-out specsconstitute the contract. Thus, if the resulting product is wrong, the worker or manufacturer are protected from liability as long as they have faithfully executed the instructions conveyed by the drawing.
If those instructions were wrong, it is the fault of the engineer. Because manufacturing and construction are typically very expensive processes involving large amounts of capital and payrollthe question of liability for errors has great legal implications as each party tries to blame the other and assign the wasted cost to the other's responsibility.
This is the biggest reason why the conventions of engineering drawing have evolved over the decades toward a very precise, unambiguous state. Standardization and disambiguation[ edit ] Engineering drawings specify requirements of a component or assembly which can be complicated.
Standards provide rules for their specification and interpretation. Standardization also aids internationalizationbecause people from different countries who speak different languages can read the same engineering drawing, and interpret it the same way. Media[ edit ] For centuries, until the post-World War II era, all engineering drawing was done manually by using pencil and pen on paper or other substrate e.
Since the advent of computer-aided design CADengineering drawing has been done more and more in the electronic medium with each passing decade. Today most engineering drawing is done with CAD, but pencil and paper have not entirely disappeared.
Some of the tools of manual drafting include pencils, pens and their ink, straightedgesT-squaresFrench curvestriangles, rulersprotractorsdividerscompassesscales, erasers, and tacks or push pins.
Slide rules used to number among the supplies, too, but nowadays even manual drafting, when it occurs, benefits from a pocket calculator or its onscreen equivalent. And of course the tools also include drawing boards drafting boards or tables.
The English idiom "to go back to the drawing board", which is a figurative phrase meaning to rethink something altogether, was inspired by the literal act of discovering design errors during production and returning to a drawing board to revise the engineering drawing.
Drafting machines are devices that aid manual drafting by combining drawing boards, straightedges, pantographsand other tools into one integrated drawing environment.
CAD provides their virtual equivalents. Producing drawings usually involves creating an original that is then reproduced, generating multiple copies to be distributed to the shop floor, vendors, company archives, and so on.
The classic reproduction methods involved blue and white appearances whether white-on-blue or blue-on-whitewhich is why engineering drawings were long called, and even today are still often called, " blueprints " or " bluelines ", even though those terms are anachronistic from a literal perspective, since most copies of engineering drawings today are made by more modern methods often inkjet or laser printing that yield black or multicolour lines on white paper.
The more generic term "print" is now in common usage in the U. In MBD, the information captured by the CAD software app is fed automatically into a CAM app computer-aided manufacturingwhich with or without postprocessing apps creates code in other languages such as G-code to be executed by a CNC machine tool computer numerical control3D printeror increasingly a hybrid machine tool that uses both.
Thus today it is often the case that the information travels from the mind of the designer into the manufactured component without having ever been codified by an engineering drawing. In MBD, the datasetnot a drawing, is the legal instrument. The term "technical data package" TDP is now used to refer to the complete package of information in one medium or another that communicates information from design to production such as 3D-model datasets, engineering drawings, engineering change orders ECOsspec revisions and addenda, and so on.
However, even in the MBD era, where theoretically production could happen without any drawings or humans at all, it is still the case that drawings and humans are involved. These workers often use drawings in the course of their work that have been produced by rendering and plotting printing from the MBD dataset.
In these cases, the drawing is still a useful document, although legally it is classified as "for reference only", meaning that if any controversies or discrepancies arise, it is the MBD dataset, not the drawing, that governs.
Systems of dimensioning and tolerancing[ edit ] Almost all engineering drawings except perhaps reference-only views or initial sketches communicate not only geometry shape and location but also dimensions and tolerances for those characteristics. Several systems of dimensioning and tolerancing have evolved.
The simplest dimensioning system just specifies distances between points such as an object's length or width, or hole center locations. Since the advent of well-developed interchangeable manufacturethese distances have been accompanied by tolerances of the plus-or-minus or min-and-max-limit types.
Coordinate dimensioning involves defining all points, lines, planes, and profiles in terms of Cartesian coordinates, with a common origin.Filtering in PowerApps is not user friendly, the option to create a view in power apps (filter) based on Sharepoint List view would make life a lot easier.
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