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An optical instrument reflector of polished metal or of glass with a film of metal.

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1. In petroleum refining, removal of final traces of impurities, as for a lubricant, by clay adsorption or mild hydrogen treating. Smoothing and brightening a surface such as a metal or a rock through the use of abrasive materials.


A contact between a specially prepared semiconductor surface and a metal point, usually maintained by mechanical periphery.


A semiconductor rectifier that uses the barrier formed between a specially prepared semiconductor surface and a metal point to produce the rectifying action.


A loose-fitting metal plug in a tapered rotameter tube which moves upward (or downward) with an increase (or decrease) in fluid flow rate upward through the tube. Also known as float.


Smoothing the surface of a metal by a rapid series of overlapping, light hammerlike blows or by rolling in a planishing mill.


Metal cutting by melting a localized area with an arc followed by removal of metal by high-velocity, high-temperature ionized gas.


1. In metal-forming operations, a prepunched hole in a metal strip into which the pilot component of the die enters in order to assure precise registration of the strip at each work station. 2. A small hole drilled ahead of a larger borehole. 3. A hole drilled in a piece of wood to serve as a guide for a nail or a screw or for drilling a larger hole.


A piezoelectric crystal used as a transducer, either to convert mechanical or acoustical signals to electric signals, as in a microphone, or vice versa, as in ultrasonic metal inspection.


1. A pole with a sharp metal point in one end that is used to hold utility poles upright while they are being installed. 2. See fire hook.


A test to ascertain the adhesive strength of bonded strips of metals by peeling or pulling the metal strips back and recording the adherence values.

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