ASME Y14.5M:2009 pdf free download – Dimensioning and Tolerancing
(a) Each dimension shall have a tolerance, except for those dimensions specifically identified as reference, max- imum, minimum, or stock (commercial stock size). The tolerance may be applied directly to the dimension (or indirectly in the case of basic dimensions), indicated by a general note, or located in a supplementary block of the drawing format. See ASME Y14.1 and ASME Y14.1M.
(b) Dimensioning and tolerancing shall be complete so there is full understanding of the characteristics of each feature. Values may be expressed in an engineering drawing or in a CAD product definition data set. See ASME Y14.41. Neither scaling (measuring directly from an engineering drawing) nor assumption of a distance or size is permitted, except as follows: undimensioned drawings, such as loft, printed wiring, templates, and master layouts prepared on stable material, pro- vided the necessary control dimensions are specified.
(c) Each necessary dimension of an end product shall be shown. No more dimensions than those necessary for complete definition shall be given. The use of reference dimensions on a drawing should be minimized.
(d) Dimensions shall be selected and arranged to suit the function and mating relationship of a part and shall not be subject to more than one interpretation.
(e) The drawing should define a part without speci- fying manufacturing methods. Thus, only the diameter of a hole is given without indicating whether it is to be drilled, reamed, punched, or made by any other opera- tion. However, in those instances where manufactur- ing, processing, quality assurance, or environmental information is essential to the definition of engineering requirements, it shall be specified on the drawing or in a document referenced on the drawing.
(f) Nonmandatory processing dimensions shall be identified by an appropriate note, such as “NONMANDATORY (MFG DATA).” Examples of nonman- datory data are processing dimensions that provide for finish allowance, shrink allowance, and other require- ments, provided the final dimensions are given on the drawing.
(g) Dimensions should be arranged to pro- vide required information for optimum readability. Dimensions should be shown in true profile views and refer to visible outlines.
(h) Wires, cables, sheets, rods, and other materials manufactured to gage or code numbers shall be speci- fied by linear dimensions indicating the diameter or thickness. Gage or code numbers may be shown in parentheses following the dimension.
(i) A 90° angle applies where center lines and lines depicting features are shown on a 2D orthographic drawing at right angles and no angle is specified. See para. 2.1.1.3.
(j) A 90° basic angle applies where center lines of fea- tures in a pattern or surfaces shown at right angles on a 2D orthographic drawing are located or defined by basic dimensions and no angle is specified. See para. 2.1.1.4.