Metrology Equipment Catalog - Rapp Industrial Sales

I N F O R M AT I O NI N F O R M AT I O NCommonly Used Terms in Quality ControlAccuracy - Conformity of an indicated value tothe true value, i.e., an actual or an acceptedstandard value.Allowance - The degree of variation permittedfrom a nominal specification; the total tolerance.Axis - A designated line on a drawing, machine,gage or part used to denote a linear direction formeasurement or reference.Calibrate - To graduate a measuring instrumentinto appropriate units. To determine accuracy ofa gage at given points over its gaging area.Clearance - The space between two matingparts. On a cutting tool, the angle between thecutting edge and the perpendicular axis ofthe work.Concentricity - The amount of conformity withone another between the centers of two circles.Datum - A point of reference.Deviation - Error, variation, or departure froma standard.Dimension - Any measurable extent ormag ni tude, as length, breadth, or thickness.Discrimination - (See Resolution)Division - A mark or graduation denoting anincremental value of a scale, dial or gage.Eccentricity - The deviation of the centers of twocircles from each other.Fit - The type and closeness of contact betweentwo surfaces, usually in reference to matingparts.Flatness - The degree of conformity of a planeor axis to a master or to a specified standard(mean or reference plane).Floating Zero - A characteristic of a machine orgaging system that permits the less than the zeroreference point on an axis to be established readilyat any point in the travel.Graduate - To mark in a regular manner theincrements of measurement, as on a rule,scale or dial. Graduation: one of the markedincrements.Interchangeable - Sufficiently alike in size as topermit replacement without modification.Limit - A specified dimension beyond which variationin size is not permissible for acceptance asconforming to size.Mean - An average. An intermediate valuebetween two or more values.Master - Any type of gage that is used to checkthe accuracy of other gages.Precision - The quality of being sharply or clearlydetermined; strictly accurate, exact. Ina gage, usually one capable of discriminationto .010" or smaller.Resolution - The smallest increment into which agage is divided. Used interchangeably withDiscrimination. Also, the least interval betweentwo adjacent discrete details which can bedistinguished from one another.Squareness - The degree of conformity of aplane or axis to a corresponding perpendicularplane or axis.Standard - Any established measure of extent,quantity, quality or value. An accurate examplefor comparison; a master.Straightness - The degree of conformity of anaxis along its length to a standard.T.I.R. (Total Indicator Reading) - The differencebetween the maximum and minimum indicatorreadings obtained, usually in measurement ofroundness.Tolerance - The total permissible amount bywhich a dimension may vary above or below aspecified size, usually expressed as plus and/orminus an amount greater or less than the specifieddimension.Info-18Rapp Industrial Sales888 789-7277