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FABRICATION. (1) A term used to distinguish production operations for components as opposed to assembly operations. (2) Processing of natural or synthetic materials for desired modification of shape and property.
FAPT. An interactive APT processor with graphic display that provides instant program verification. It simultaneously provides a readout of the commands programmed and generates 2-D contours or simulated 3-D surfaces for visual program check.
FEEDBACK. The signal or data sent back to a commanding unit from a control machine or process for use as input in subsequent operations. When applied to a transmission, feedback is the return of a fraction of the output to the input. In a closed-loop system, it is the part of the system which brings back information about the condition under control.
FEEDBACK CONTROL. Action in which a measured variable is compared to its desired value to bring it closer to the desired value.
FEEDBACK CONTROL LOOP. A closed transmission path which includes an active transducer and consists of a forward path, a feedback path, and one or more mixing points arranged to maintain a prescribed relationship between the loop input and output signals.
FEED RATE. The rate of movement between a machine element and a workpiece in the direction of cutting. Expressed as a unit of distance relative to time; a machine function such as spindle rotation or table stroke.
FEELER. A device used to sense a "two-state condition,'' such as on-off, go-no-go, open-closed.
FIELD. A set of one or more characters which is treated as a unit of information.
FIRMWARE. (1) A term usually related to microprogramming and those specific software instructions that have been more or less permanently burned into a ROM control block. (2) An extension to a computer's basic command (instruction)- repertoire to create microprograms for a user-oriented instruction set. This extension to the basic instruction set is done in read-only memory and not in software. The read-only memory converts the extended instructions to the basic instructions of the computer.
FIXED-BLOCK FORMAT. An arrangement of data in which the number and sequence of words and characters in successive blocks, as determined by hardware requirements or the programmer, are constant.
FIXED SEQUENTIAL FORMAT. A numerical control format where each word in the format is identified by its position.
FIXED STORAGE. A storage device used to store data that is not changeable by computer instructions, such as magnetic core storage with a lockout feature.
FIXED ZERO. A reference position of the origin of the coordinate system; usually a characteristic of machines with absolute feedback elements.
FIXTURE. A device to hold and locate a workpiece during inspection or production operations. Many fixtures are used on machine tools and often provide means for cutter setting.
FLEXOWRITER. An automatic typewriter incorporating an eight-track tape reader and punch for preparation of punched tape.
FLIP FLOP. (1) A type of circuit having two stable states and usually two input terminals (or signals) corresponding to each of the two states. The circuit remains in either state until the corresponding signal is applied. Also, a similar bistable device with an input which allows it to act as a single-stage binary counter. (2) A bistable device; a device capable of assuming two stable states; a bistable device which may assume a given stable state depending upon the pulse history of one or more input points and having one or more output points. The device is capable of storing a bit of information, controlling gates, etc.; a toggle.
FLOATING ZERO. A characteristic of an NC machine control unit allowing the zero reference point of an axis to be established at any position over the full travel of the machine tool.
FLOPPY DISK. A flexible, magnetic-based disk used to store data input to NC machine control units and computers.
FLOPPY DISK SYSTEMS. A typical floppy disk provides random access program/data storage. Hard-sector formatted, each disk holds over 300,000 data bytes. Because many floppy controllers have all of their intelligence in microcode, some microcontrollers offer features not practical in designs implemented with hard-wired logic. The host-computer driver need only issue a small sequence of commands to write or read data from the disk.
FLOWCHART. A graphical representation of a problem or system, in which interconnected symbols signify operations, data flow, equipment, etc. It is used in defining, analyzing, or solving a problem.
FLUIDICS. The technique of control that uses only a fluid to perform sensing, control, information processing, and actuation functions without moving elements.
FORMAT. The physical arrangement of data on a program tape, and the pattern in which it is organized for presentation.
FORMULA TRANSLATION (FORTAN). Any of a family of universal procedure-oriented languages used to describe numeric processes in such a way that both humans and computers can understand them.
FUNCTION. A specific purpose or characteristic action of an entity, such as a subroutine of a program.
FOURIER ANALYSIS. The determination of the harmonic components of a complex waveform either mathematically or by a waveanalyzer device.
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