Defination of Metrology
Assembly - the connection of two or more separate parts to make a new single part.
Basic Dimension - The target dimension for a part. This typically has an associated tolerance.
Dimension - A size of a feature, either measured, or specified.
Dimensional Metrology - The use of instruments to determine object sizes shapes, form, etc.
English System - See Imperial.
Error - a discrepency between expected, and actual values.
Imperial System - An older system of measurement, still in use in some places, but generally replaced by the metric system.
Limits - These typically define a dimensional range that a measurement can be expected to fall within.
Machine Tool - Generally use to refer to a machine that performs a manufacturing operation. This is sometimes confused with the actual cutting tools, such as a drill bit, that do the cutting.
Measurement - The determination of an unknown dimension. This requires that known standards be used directly, or indirectly for comparison.
Metric System - A measurement system that has been standardized globally, and is commonly used in all modern engineering projects.
Metrology - The science of measurement. The purpose of this discipline it to establish means of determining physical quantities, such as dimensions, temperature, force, etc.
Precision - Implies a high degree of accuracy.
Repeatability - Imperfections in mechanical systems can mean that during a Mechanical cycle, a process does not stop at the same location, or move through the same spot each time. The variation range is refered to as repeatability.
Standards - a known set of dimensions, or ideals to compare others against.
Standard Sizes - a component, or a dimension that is chosen from a table of standard sizes/forms.
Tolerance - The allowable variation in a basic dimension before a part is considered unacceptable
