Glossary C

cabinet oblique	(n) A type of oblique pictorial drawing in which the two dimensions of the frontal surface are drawn parallel to the frontal plane, and the third (receding) axis is drawn obliquely at half the scale of the frontal plane. The receding axis is typically drawn at an angle of between 45 and 60 degrees.
cabling diagram	(n) See wiring diagram.
CAD	(v or n) Acronym for computer-aided drafting, computer-aided design, or computer-aided design/drafting. The usage depends on the context in the design process and on whether the acronym refers to the physical computer system or the activity of using such a system to support technical and engineering graphics.
callouts	(n) See line balloon.
cam	(n) A mechanical device used to transform rotary motion into reciprocating motion, using a rolling or sliding contact with another part called a cam follower. Radial cams move the follower perpendicular to the shaft; cylindrical cams move the follower parallel to the shaft. The shape of the contact surface determines the motion of the follower.
CAM	(n) Acronym for computer-aided manufacturing, which is the use of computers to control the production process. Examples are robots for assembly and numerically controlled machine tools. CAM is often combined with CAD to describe the integration of design and manufacturing through the use of a common computer database.
cam follower	(n) A mechanical device in which one end follows a linear, reciprocating path as the other end traces the surface of a rotating cam. Followers are often spring loaded to guarantee a good contact with the surface of the cam.
CAPP	(n) Acronym for computer-aided process planning, a technique that uses computers to assist in the planning process. CAPP is an expert computer system that can be used to determine the optimal sequence of operations for a part and can then generate the optimal process and routing sheets necessary to make the part.
cap screw	(n) A mechanical threaded fastener with a head on one end, used to screw into a mating part. Differing from a bolt, a cap screw has a longer thread length and does not use a nut.
Cartesian coordinate system	(n) Common coordinate system used in mathematics and graphics to locate the position of geometry in space. First introduced in 1637 by Rene Descartes (1596–1650), the system is typically used to locate points in 2-D (X,Y) or 3-D (X,Y,Z) space by assigning values to the points based on the mutually perpendicular (orthogonal) axes.
cavalier oblique	(n) A type of pictorial drawing in which the two dimensions of the frontal surface are drawn parallel to the frontal plane, and the third (receding) axis is drawn obliquely to the frontal plane and at the same scale. The receding axis is typically drawn at an angle of between 45 and 60 degrees.
CD-ROM	(n) Acronym for compact disk-read only memory, a mass storage device that uses optical technology to store large amounts of information on a small reflective platter. Information is written to the disk only once, at which point the disk is unchangeable. CD-ROMs are used for archiving audio, graphic, and textual information, and for publishing and distributing software, graphic images, multimedia materials, etc.
center lines	(n) A type of linestyle used to represent symmetry and paths of motion and to mark the centers of circles and the axes of symmetrical parts, such as cylinders and bolts. Unlike visible and hidden lines, center lines do not represent geometry directly.
central view	(n) The view from which related views are aligned in an orthographic drawing. Distances and features are projected or measured from the central view to create the adjacent views.
ceramics	(n) Materials, usually with crystal structures, created from compounds of metallic and nonmetallic elements. Ceramics can withstand high temperatures and resist wear. Some ceramics, such as glass, are not crystalline in structure.
chamfer	(n or v) A beveled corner used on the opening of a hole and the end of a cylindrical part to eliminate sharp corners. Chamfers facilitate the assembly of parts and are specified by giving a linear and angular dimension. When used as a verb, the term refers to the process of creating a chamfer on an object.
check print	(n) A type of hard-copy output used to check the accuracy and format of a technical drawing. The check print is a low-quality, high-speed method of troubleshooting the final print or plot.
chemical engineering	(n) A field of engineering that includes all phases of technical activities in which a knowledge of chemistry, along with other basic sciences, is used to solve problems related to energy, health, the environment, food, clothing, shelter, and materials.
CIM	(n) Acronym for computer-integrated manufacturing, a system for linking manufacturing operations into a single integrated computer system. CIM differs from CAD/CAM primarily in its integration of business functions, such as accounting, marketing, and personnel, into a common computer database shared by all components of the business.
circle	(n) A closed, planar curve that, at all points, is an equal distance (the radius) from a point designated as the center. A circular arc is an open, planar curve equidistant from a center. The arc will subtend an angle of less than 360 degrees. A circle is sometimes described as a 360-degree arc.
circuit side	(n) The side of a printed circuit board on which a majority of the circuit connections for components are made. The opposite side of the board is called the component side.
circularity (roundness)	(n) A form control for geometric dimensioning and tolerancing. For a cylinder or cone, circularity means that all points on a surface intersected by a plane passing perpendicular to a common axis are equidistant to that axis. For a sphere, all points on a surface intersected by a plane passing through the center are equidistant to that center.
civil engineering	(n) A field of engineering involved with planning, design, construction, operation, and maintenance of transportation, environmental, and construction systems. Along with military engineering, this field is often considered the first true engineering field.
clash	(v) A condition in which two parts of a mechanism partially overlap in space, causing interference. Kinematic analysis using the Boolean intersection operation is often used to evaluate clashes in computer models of the mechanism.
clearance fit	(n) A tolerancing measure used to describe a fit in which two mating parts always leave a space when assembled. The resulting space is called an allowance or a clearance and is usually specified in the assembly drawings.
clip	(v) The rendering process of removing portions of lines or surfaces that reside outside the view volume. Clipping refers to removing the portion of the model that resides outside the horizontal and vertical bounds of the viewing area and outside the specified near and far depth (Z) bounds.
clock speed	(n) The rate at which the central processing unit (CPU) of the computer performs functions. The clock speed is measured in megahertz (MHz). The higher the clock speed, the more powerful the CPU.
closed loop	(n) The condition required for a group of edges to form a face (surface) on an object. The edges must be connected end to end, forming a continuous path around the perimeter of the face.
CNC	(n) Acronym for computer numeric control, which describes a form of programmable automation of a machine tool using a computer in the controller unit. In a computer controlled manufacturing center, the individual machines would use CNC programs, either sent from a main computer or programmed locally.
color	(n) The perceptual quality of a surface that results from the combined response to lightness, hue, and value. Hue is often confused with color since the names of hues (e.g., red, purple, yellow, etc.) are used as the primary classification terms for color.
color lookup table	(n) A modular database that allows colors to be mapped to specific data values in a visualization. The color lookup table can be associated with a single rendered image or be used as a standard table in a library. Color lookup tables are often referred to as palettes.
command history	(n) A listing of commands entered into the CAD system by the user, along with the values of the specified parameters. Command histories can be used as a “script” to replay sequences of commands or track down input errors.
composites	(n) The combination of two or more materials, one a reinforcing element and the other a resin binder or matrix. A common composite is fiberglass, which is made of glass fibers and a resin. The more advanced reinforcing elements include carbon/graphite, boron, and Kevlar (aramid), which are stiff, strong, and lightweight.
computer-aided drafting/design (CAD)	(n) See CAD.
computer-aided manufacturing (CAM)	(n) See CAM.
computer animation and simulation	(n) Simulation is the precise modeling of complex situations that involve a time element; animation is the imprecise modeling of complex situations over time. An animation will replicate a real situation by approximate means; a simulation will replicate a real situation by accurate means.
computer-integrated manufacturing (CIM)	(n) See CIM.
computer numeric control (CNC)	(n) See CNC.
conciseness	(adj.) A term used to describe one attribute of a CAD database. The more concise the database, the less space each record takes in the hard drive of the computer.
concurrent	(adj.) The technique of organizing numerous steps so that they happen in parallel rather than one after another (serially). Concurrent engineering, for example, involves all members of the design process working simultaneously in close coordination with each other rather than each member waiting for other members to finish with their components of the design.
cone	(n) A geometric solid described by a straight line (the generatrix), one end of which is attached to a fixed point (the vertex) and the other end of which traces a closed, curved path. The most common cone is a right circular cone, for which the curved path is a circle and the vertex lies on an axis that is perpendicular to the circle and through its center.
cone of vision	(n) A term used to describe the amount of space visible by the human eye looking in a fixed direction. The visible volume is approximately described by a right-angled cone for which the vertex is at the eye and the axis is aligned with the view direction.
conics	(n) Special case single-curved lines that can be described in many different ways: sections of a cone, an algebraic equation, and the locus of points. For our purposes, conics are sections of a right circular cone and include the ellipse, parabola, and hyperbola. The circle is a special-case conic.
connection list	(n) The list of all connections that need to be made between components on an electronic circuit board. This list is usually managed by the electronic CAD program.
connectors	(n) Devices used to join electronic components together to allow the transmission of signals. Connectors include plugs (external components) and jacks or receptacles (internal components) and can provide either temporary or permanent connections. Devices used for mechanical connection are typically called fasteners.
constraint	(n) A mathematical requirement placed on geometric elements in a 3-D model. Dimensional constraints define the distance between two geometric elements while geometric constraints define a relationship such as parallelism or perpendicularity between elements. The operator establishes an explicit constraint while the software automatically places an implicit constraint. A fully constrained feature has all of its geometry unequivocally defined while an underconstrained feature does not. An overconstrained feature has conflicting geometric requirements.
construction geometry	(n) Any geometry created as part of the CAD modeling process that does not represent actual part geometry. Example of this would be workplanes, axes, or points used to locate geometry in a solid model.
construction lines	(n) Light, thin lines drawn to lay out the framework or structure of a drawing or sketch. Portions of these lines are often overdrawn with the final linework.
constructive solid geometry (CSG)	(n) A method of 3-D solid modeling in which geometric primitives are related to each other in a binary tree structure via Boolean operations. Each primitive is defined as a solid by a group of analytic surfaces (half-spaces), and the final object is defined by the calculation of the Boolean operations between primitives.
continuity	(adj.) A term used to describe the transition between two elements. Elements are continuous if there is no gap or break between them and there is a single mathematical function used to describe the two combined elements. Continuity is often used to describe the connection of two curved lines or surfaces.
contour line	(n) A line that represents the independent variable (X,Y) combinations that result in a constant dependent variable value (also called an isoline). A contour line can also represent the juncture between two surfaces of differing orientations or depths. In this definition, a contour line is an alternate term for edge.
contour plot	(n) A visualization in which the horizontal and vertical scales both represent independent variable values, and the contour lines show the mapping of constant, dependent variable values. Multiple contour lines are typically drawn on a plot, representing a uniform sampling of dependent variable values.
contour sketch	(n) A technique to develop the visual acuity of a novice sketcher by sketching the outline of an object.
controlling	(v) The procedures used to control materials, machines, and processes in the manufacturing and production cycle through automation, measuring, inspection, and testing.
control points	(n) Points used in conjunction with spline curves. These points are not part of the curve proper, but the relationship between the control points and the points on the curve is used to define the shape of the curve.
conventions	(n) Commonly accepted practices, rules, or methods. In technical drawing, a convention is the use of dashed lines to designate a feature hidden from the current viewpoint.
convolute	(n) A single-curved surface generated by a straight line moving such that it is always tangent to a double-curved line.
Coons’ surface	(n) A 3-D surface defined by input curves. This surface was named after Steven A. Coons, who developed the mathematical method for defining complex shapes used in the design of aircraft, automobiles, and ships’ hulls.
coordinate dimensioning	(n) A technique in which all dimensions are calculated as Cartesian X and Y distances from an origin point, usually located at the lower left-hand corner of the part. Also known as datum dimensioning or baseline dimensioning, coordinate dimensioning should be used cautiously because of the tolerance stackup that takes place.
coordinates	(n) A set of real numbers defining the location of a point in space. One value is given for each dimension of the space (i.e., 2-D, 3-D), and each value is determined by the point’s distance from the defined origin.
corner	(n) The nontangential intersection of two or more surfaces of an object. The intersection of two surfaces is usually referred to as an edge. Corners are represented on a drawing by either a single line or multiple co-terminating lines.
CPU	(n) Acronym for central processing unit. The CPU is the heart of the computer, coordinating all primary activities of the computer and processing a majority of operations or “calls” from the software. Computers are often classified by their CPUs. Examples are Intel’s PentiumTM and Motorola’s PowerPCTM 601.
crest	(n) A threading term describing the peak or top surface of a screw thread.
CRM (customer relationship management)	(n) Use proven methodologies and e-business technologies to help enable companies to identify, select, acquire, develop, and retain profitable customers, building the lasting relationships that are key to long-term financial success.
cross-hatch lines	(n) An alternate term for section lines. Cross-hatch often refers to section line symbols in which the lines cross each other rather than simply running parallel to each other.
curved line	(n) A line which does not follow a straight path. Curved lines are often classified by their underlying mathematical functions. Examples are circular and elliptical curves.
cutting plane	(n) An imaginary plane in space used to define the division between two parts of an object. A cutting plane is often used to define a portion of an object to be removed in order to reveal the interior detail.
cutting plane lines	(n) A line showing the location of a cutting plane in section drawings. The cutting plane line is drawn in the view for which the line of sight is parallel to the cutting plane. Arrows on the ends of the section line point toward the material to be retained in the corresponding section view.
cycle time	(n) The total time required for a process to take place.
cycloid	(n) A curve generated by the motion of a point on the circumference of a circle that is rolled in a plane along a straight line.
cylinder	(n) A planar geometric solid described by a straight line (the generatrix) that traces a closed, curved path and always stays parallel to itself. The most common cylinder is a right circular cylinder for which the curved path is a circle and the generatrix is perpendicular to the path.
cylindrical coordinates	(n) A system for locating points in space with one angle and two lengths. Cylindrical coordinates describe a point as a distance from the origin, its angle in the X–Y plane, and its Z value. Cylindrical coordinates are useful when designing circular shapes and geographic applications.
cylindricity	(n) A form control for geometric dimensioning and tolerancing. Cylindricity indicates that all points on the surface should be equidistant from a common axis. Unlike circularity, cylindricity refers to both the circular and the linear (longitudinal) elements on the surface.