NOMINAL SIZE : The size used for general description. Tolerance is the allowable variation for any given size in order to achieve a proper function. Precision is the degree of accuracy necessary to ensure the functioning of a part as intended. The working parts have a definite relationship with each other: free rotation, free longitudinal movement, clamping action, and permanent fixed position. Parts of a machine are designed in order to make a function. Manufacturing precision taken into the product determines its quality, its cost and selling price. In a manufacture of a machine, quality is a primary consideration. In an assembly process the degree of 'clearance' or 'tightness' desired between mating parts is important. To many standards like ANSI(Inch System), ISO (Metric System) etc. Tolerancing is just like written languages.
ANSI and ISO Geometric Tolerancing Symbols.
