Glossary E-F

E-business	(n) The process of using Web technology to help businesses streamline processes, improve productivity, and increase efficiencies. Enables companies to easily communicate with partners, vendors and customers, connect back-end data systems, and transact commerce in a secure manner.
E-business infrastructure	(n) The hardware and software technology necessary to support the day-to-day activities in the digital enterprise.
ECO	(n) See engineering change order.
E-commerce	(n) The ability to buy and sell products and services over the Internet. Includes online display of goods and services, ordering, billing, customer service and all handling of payments and transactions.
edge	(n) The intersection or boundary of two nontangential surfaces (faces). An edge is represented on a technical drawing as a line or a change in shading gradients in a rendered image.
edge view	(n) The view of a surface such that it is seen as a line. For a planar surface, the edge view is an orthographic view parallel to the plane in which the surface resides.
efficiency	(adj.) With respect to CAD, the speed with which software can execute a command. This is reflected in the amount of computer processing time required to execute a command.
elastomers	(n) A special class of polymers that can withstand elastic deformation, then return to their original shape and size. Natural rubber, polyacrylate, ethylene propylene, neoprene, polysulfide, silicone, and urethane are types of elastomers.
electrical engineering	(n) A field of engineering that includes the research, development, design, and operation of electrical and electronic systems and their components.
elevation drawing	(n) A type of drawing commonly used in civil, architectural, or engineering projects involving large structural layouts. An elevation drawing (sometimes called an elevation view) is an orthographic view perpendicular to the line of gravity (i.e., parallel to the terrain). These drawings are useful in planning the vertical arrangement of components within a structure, or of the structure relative to the terrain, and are also used to make aesthetic judgments since this view closely matches how the structure would be seen.
ellipse	(n) A single-curved line primitive. An ellipse is a conic section produced when a plane is passed through a right circular cone oblique to the axis and at a greater angle with the axis than the elements. An ellipse also describes a circle or circular arc viewed at any angle other than normal (perpendicular).
engineer	(n) A professional concerned with applying scientific knowledge to practical problems. The discipline is divided into a number of specialties, such as civil, mechanical, chemical, electronic, aerospace, electrical, and industrial engineering.
engineering change order (ECO)	(n) A document that begins the process for making changes in a design. Normally, the ECO will be documented in an engineering change note (ECN). A copy of the engineering drawing is attached to the order, with sketches and a written description of the change. A reference number is given to the change order so that it can be traced within the organization.
engineering graphics	(n) A communications method used by engineers and other technical professionals during the process of finding solutions to technical problems. Engineering graphics are produced according to certain standards and conventions so that they can be read and accurately interpreted by anyone who has learned those standards and conventions.
envelope principle	(n) A term used in geometric dimensioning and tolerancing to describe how much a feature can deviate from ideal form, orientation, or position as it departs from maximum material condition.
ergonomics	(n) A technical field concerned with optimizing the interface between humans and technology. The field has numerous specialties, including industrial safety and hygiene, human–computer interface design, and the design of control panels in manufacturing plants, cars, airplanes, etc.
ERP (enterprise resource planning)	(n) Helps businesses streamline and manage critical operations such as inventory maintenance, supplier interaction, product planning, purchasing, customer service and order tracking. Supported by multi-module application software, it links together fragmented operations and shares data across an integrated set of application modules.
error bar	(n) A mark added to data points in graphs and plots to indicate the range of probable values. Since perfect accuracy is not possible in any kind of experimental method, the error bar represents the degree of certainty in the data value. The length of the bar usually represents the statistic of standard deviation.
error checking	(v) The process of evaluating actions requested by the operator to determine if such actions resulted in invalid geometry. Depending on the system, error checking may be done automatically (such as when a file is saved to disk) or manually at the request of the user.
etching	(n) The method of creating patterns, typically in metal, using chemical processes. In the electronics industry, etching is used to remove conductive material, usually copper, from printed circuit boards to create wiring patterns. The wiring pattern is printed on the board in a chemically resistant ink, and the rest of the conductive material is then dissolved away in a chemical bath.
Euler operations	(v) Low-level operations used to construct models from geometric primitives, such as vertices, edges, and faces. The validity of the model is guaranteed by a simple mathematical formula, credited to both Leonhard Euler (1707–1783) and Jules Henri Poincaré (1854–1912).
evaluated	(adj.) A description of a model for which the final form is explicitly represented in the database. An evaluated model is not concise (it may take up large amounts of memory), but it is efficient (calculations on the model are processed quickly).
exploded assembly	(n) An assembly drawing, usually a pictorial, in which the parts of the assembly are spread apart (exploded) from their functional location in order to provide a larger, clearer view of the features of the individual parts. Flow lines are used to relate the parts to each other and to demonstrate assembly. This type of assembly drawing is used extensively for technical illustrations in such applications as parts catalogs and assembly instructions.
exposure	(n) The orientation of a principal surface of an object relative to the image plane. The greater the exposure, the closer the surface(s) is to being parallel to the image plane and, therefore, the lower the distortion caused by foreshortening.
extension line	(n) A thin, solid line perpendicular to a dimension line, indicating which feature is associated with the dimension.
fabrication drawing	(n) An electronics drawing that presents the complete engineering for the manufacture of a printed circuit board. The fabrication drawing contains an accurate to-scale layout of the board shape, drill hole locations, material and manufacturing specifications, and conductor pattern. The conductor pattern is broken out to make an artwork drawing, a screen print drawing, and the mask used in board etching. The drill hole information is sometimes broken out into a separate drill drawing for use in programming the drill patterns.
face	(n) A distinct planar or curved surface or region on an object. One or more faces joined together at edges define the boundary between object and nonobject. A face is a topological element in a 3-D model.
face-edge-vertex graph	(n) The data structure used by boundary representation (B-rep) 3-D solid modelers. The graph contains both geometric information on the location and size of geometric elements and topological information on how they are linked together.
facets	(n) Repeating groups of polygons of similar topology, forming an approximate representation of a curved surface. Curved surfaces such as cylinders and spheres are subdivided into a series of faceted planar surfaces, which approximate the original surface. This transformation is often used so that curved surfaces can be rendered using algorithms that only support planar surfaces.
faithful	(adj.) A measure of whether a computer model contains or imparts sufficient information to fulfill its task. In order to define the faithfulness of a model, the exact use of the model must be known.
familiar size	(n) A perceptual cue in which the known (familiar) size of an object is used to judge its distance from the observer. Often, the comparison of the perceived size of two objects is used to judge their relative locations in depth.
family of parts	(n) Similar parts that can be grouped together. A family of parts might be a series of air cylinders that have many common topologies but have variations in the geometry of certain features, such as the diameter or length of the head. Parametric techniques can be used to represent a family of parts on the computer or in drawings.
fastener	(n) A mechanical device that constrains two or more parts. Fasteners can rigidly join parts or can allow certain degrees of freedom. Some fasteners are meant to be disassembled for maintenance (e.g., screws and bolts), while others are considered permanent (e.g., rivets).
feature	(n) A general term applied to physical portions of a part. Features typically serve a function, either in the final application of the part or in the specification or manufacture of it. Examples are a hole, slot, stud, or surface.
feature control frame	(n) A rectangular outline containing geometric dimensioning and tolerancing information used in the engineering, production, and inspection of a part. The left-hand compartment inside the frame contains the symbol of the geometric control being applied. The middle compartment contains the size of the tolerance zone. The right-hand compartment contains the datum identification symbol(s).
feature of size	(n) A feature that is measurable; specifically, a spherical or cylindrical surface, or a pair of parallel plane surfaces, associated with a feature.
feature tree	(n) A computer interface element common to most constraint-based solid modelers. The feature tree lists the geometric features contained in the model in order in which they are interpreted by the modeler. New features will typically be placed at the bottom of the tree. A feature in the tree can be construction geometry, part features, or components in an assembly.
feed-through	(n) A through-hole in a printed circuit board which has a conductive surround on at least one side of the board and sometimes in the hole. The conductive pads or donuts on either side of the hole are used to make electrical connections through the board and with component wires that are soldered into the holes.
FEM/FEA	(n) See finite element modeling and analysis.
fillet	(n) A rounded interior corner normally found on cast, forged, or molded parts. Like a round, a fillet can indicate that a surface is not machine finished. A fillet is indicated on engineering drawings as a small arc.
finite element modeling and analysis (FEM/_FEA)	(n) An analysis technique used extensively to model and analyze forces within a computer model or a proposed design. In the modeling phase, the continuous surface or volume is discretized into a finite number of linked primitive geometries. In the analysis phase, the model is subjected to theoretical forces applied at certain locations, and the resulting forces are calculated across the rest of the model.
fittings	(n) A term used to describe components that connect pipes, valves, and other fluid and gas-handling equipment. Fittings are often classified by the method used to join the components together. Some of the most common types are welded, threaded, and flanged (bolted).
fixture	(n) A rigidly held production tool that securely holds, supports, and locates the workpiece. Unlike a jig, a fixture is not used to guide a cutting tool.
flatness	(n) A form control for geometric dimensioning and tolerancing. Flatness indicates that all points on the surface must lie in a plane. Flatness for a planar surface is comparable to straightness for a line.
flat shading	(v) A rendering method that uniformly adjusts the value of a surface color based on its orientation to the light. This method is considered the simplest shading method since it only requires the calculation of a single surface normal.
flexible manufacturing system (FMS)	(n) A group of machines that can be programmed to produce a variety of similar products. For example, an automobile parts supplier might specialize in the production of gears for transmissions. An FMS cell might be used to produce the gears for more than one automobile manufacturer because the parts are similar.
flow charts	(n) A visualization technique for displaying relationships in time, particularly for data that doesn’t conform well to scalar mapping. PERT charts and other types of flow charts are project management tools used to map the relationship of specified project tasks, personnel, and other resources on a single timeline.
flow diagram (chart)	(n) A diagram used in electronic and piping systems to describe the system’s process and the flow of material (or electronic signals) through the proposed design. Since these diagrams only depict the functional nature of the system, they do not show the true spatial layout or geometry of the components.
flow lines	(n) Lines used primarily in technical illustrations to indicate the assembly of parts in an exploded assembly. Flow lines are thin phantom lines drawn parallel to the line of assembly between two parts. Right-angle jogs are placed in the flow line when the drawing of the part has been moved away from the direct line of assembly for reasons of clarity.
FMS	(n) See flexible manufacturing system.
focus point	(n) A location where reflecting rays from a (parabolic or hyperbolic) surface converge. Focus point describes both the physical phenomenon of light rays reflecting from a mirrored surface and the abstract geometric calculations of line paths.
fold line	(n) A basic concept in descriptive geometry used to define a line that is perpendicular to projection lines and is shared between views of a drawing. A fold line can also describe the “hinge” line between the image planes of the glass box used to define orthographic multiviews.
font	(n) The size and style of text characters.
foreshortened	(adj.) The reduction in size of one or more dimensions of a planar face due to the face not being perpendicular (normal) to the line of sight. The dimension foreshortened is defined by the axis of rotation of the face out of a plane normal to the line of sight. When the face is rotated in its edge view, the foreshortening is applied to a line.
forming	(v) A process in which components are held together by virtue of their shape. This is the least expensive fastening method, and it may or may not be permanent. Heating and air conditioning ductwork is held together by forming the sheet metal.
four-color printing	(n) A color printing process in which a full-color image is divided into four separate images, each representing the amount of one of the three subtractive primary colors (cyan, magenta, and yellow) or black contained in the image. Printing plates are made from the new images, and each is printed in a single ink color as an overlay. This process is also called the CMYK system, an acronym for the four ink colors, where K is for black.
fractal	(adj.) The term, short for fractional dimensional, used to describe graphics with randomly generated curves and surfaces that exhibit a degree of self-similarity. Fractal design tools provide new opportunities for designers to produce complex patterns with more visual realism than can be output from conventional geometry programs.
free-form surface	(n) Three-dimensional surfaces that do not have a constant geometrical shape. Free-form surfaces follow no set pattern, are classified by their use as constrained or unconstrained, and are typically produced using sophisticated CAD programs.
frontal line	(n) A line that is seen in its true size in the frontal plane.
frontal plane	(n) A principal orthographic plane of projection. This plane is used to define both the front and back orthographic views.
front view	(n) A principal view of an object, typically the first one defined, orienting the object such that the majority of its features will be located in the front, right side, and top views.
full section	(n) A sectional view generated by passing a single cutting plane completely through the object.
functional analysis and design	(n) A design driven by the intended use of the product. Functional analysis determines if the design is an answer to the problem statement written during the ideation phase. Aesthetic considerations are often considered the foil to functional considerations.
fundamental deviation	(n) A tolerancing measure used to describe the deviation closest to the basic size.