ASME Y14.2-2008 pdf free download.Line Conventions and Lettering.
ASME Y14.2 establishes the line and lettering practices for use in the preparation of drawings, including the recognition of the requirements for computer aided design (CAD) and manually prepared drawings.
1.2 Units of Measurement
All dimensions used in this Standard are in millimeters, except in Mandatory Appendix I.
1.3 Applicable Documents
The following revisions of American National Standards form a part of this Standard to the extent specified herein. A more recent revision may be used, provided there is no conflict with the text of this Standard. In the event of a conflict between the text of this Standard and the references cited herein, the text of this Standard shall take precedence.
ASME Y14.3M-2003, Multiview and Sectional View Drawings
ASM E Y l4.5M- 1994, Dimensioning and Tolerancing
Publisher: The American Society of Mechanical Engineers (ASME), Three Park Avenue, New York, NY 10016-5990; Order Dept: 22 law Drive, P 0. Box 2900, Fairfield, NJ 07007-2900
2 LINE CONVENTIONS
Line conventions describe the sue, construction, and application of the various lines used in making drawings. Paragraphs 2.1 through 2.14 identify the type and style of lines for use on drawings.
2.1 LIne Widths
Two widths of lines should be used on drawings (see Fig. 1). The thin line width shall be 0.3 mm minimum. The thick line width shall be 0.6 mm minimum. liwse approximate line widths arc intended to differentiate between thick and thin lines and are not values for control of acceptance or rejection of drawings. All lines of the same type shall be uniform throughout the drawing. The ratio of line widths should be approximately two- to-one (2:1).
2.2 Line Spacing
Spacing between parallel lines may be exaggerated to a maximum of 3 mm, so there is no fill-in when the drawing is reproduced.
2.3 Visible Lines
Visible lines are continuous and shall be used for representing visible edges or contours ol objects (see Figs. I and 2).
2.4 Projection Line
Projection lines arc lines used to indicate the line of sight between two successive orthographic views.
2.5 Hidden Lines
Hidden lines .ire used to represent hidden edges and contours. They consist of short evenly spaced dashes and are used to show the hidden features of an object (see Figs. I and 2). The length of the dashes may vary slightly in relation to the scale of the view.
Hidden lines should begin and end with a dash in contact with the visible or hidden line from which they start or end, except when such a dash would form a continuation of a visible line or when a CAD system has limitations that cannot comply with these requirements. Dashes should join at corners, and arcs should start with dashes at tangent poinis (see Fig. 3).
When features located behind transparent materials are depicted, they shall be treated as concealed features and shown with hidden lines. Hidden lines should be omitted when their use is not required for the clarity of the drawing.
2.6 Section Lines
Section lines are used to show surfaces cut by a cutting plane. They are drawn as a pattern of straight, equally spaced, parallel lines used to indicate the cut surfaces of an object in section views (see Figs. I and 2).
2.6.1 General Principles. Cut surfaces of sectional views may be identitied by using section lines. Section lines are optional and may be used when necessary to distinguish individual components of an assembly or to distinguish different surface levels of a full or partial section through a part (see ASME Y14.3M).
Lettering should not be placed in section areas. However when it is unavoidable, the section lines shall be omitted in the area for the lettering (see Fig. 4).