Assembly Drawings Definition; Description Assembly drawings show how individual parts fit together to make a machine. An assembly drawing is a drawing of an entire machine or system with all of its components located and identified. Required for most products Generally multiview (orthographic projection) with as few views as possible Sections are common Few or no hidden lines Few or no dimensions Different Types; Assembly Drawings General Assembly; all parts are drawn in their working position Detail Assembly; all parts are drawn in their working position with dimensions Sub Assembly Pictorial Assembly Exploded Assembly; the parts are separately displayed, but they are aligned according to their assembly positions and sequences Elements of an Assembly Drawing One or more views Auxiliary, section, and enlarged views as needed Arrangement of parts Overall size and assembly dimensions Manufacturing processes associated with assembly Identification numbers Parts list 1
Example Drawing; General Assembly Detail Assembly Working-drawing assembly Less common Uses fewer sheets Sometimes used in a manufacturer s catalog or web site Subassembly Combined with part components to form the general assembly Includes item numbers and parts list Requires own detail drawings Examples; a car engine, bike derailleur, compressor in an AC Pictorial Assembly Assist workers in product assembly Product catalogs or brochures Sales promotion Customer self-assembly Maintenance procedures Identification Numbers Item numbers (ALWAYS numbered BOTTOM UP). Key the parts from the assembly drawing to the parts list Generally placed in balloons; balloon size.500 diameter hardcopy Some companies use identification letters Leader arrowheads or dots 2
Parts List Also known as Bill of Materials (BOM) Also known as List of Materials Usually combined with the assembly drawing Location above or to the left of the title block Upper right or left corner of the sheet alternate location Convenient location on the drawing field Can appear on a separate sheet Must include clear and complete purchase part information. If it is NOT a standard part then the actual company name must be included in with the description. Elements of a Parts List (see also Drawing Order below) Item number (find number); ALWAYS BOTTOM UP Quantity required Part or identifying number (company assigned) Nomenclature or description Material identification Vendor information; name of company if NOT a standard part Sheet number Placing ALL Information 3
Leader lines point to the corresponding part. Balloons containing part numbers. Balloons are placed in orderly horizontal or vertical rows (aligned order) Leader lines; - should not cross, - be as parallel as possible. 4
Parts list may be placed in the lower right corner of the drawing. - Part# 1 is at the bottom. Standard Parts Standard parts include any part that can be bought off the shelf. They do not need to be drawn. Purchasing information is given on the standard parts sheet attached to the back of the working drawing package. Drawing Order Drawings included in a working drawing package should be presented in the following order. Assembly drawing (first sheet) Part Number 1 Part Number 2... Standard parts sheet (last sheet) 5
Parts List Text Justification Use Middle, Center for Part #, and Qty. Use Middle Left for Part Numbers and Descriptions. General Practices The number of views can be one, two, three or more as needed, but it should be kept to a minimum. Good viewing direction is that what represents all (or most) of the parts assembled in their working position. Hidden lines usually omitted unless they are absolutely necessary to illustrate some important feature that the worker might otherwise miss. Leader lines to balloons do not cross. Leader lines are drawn in the oblique direction, every 15 degrees angles but NOT drawn at 0, 90, 190, or 270 degrees. Balloons are created at diameter.500 (hardcopy). Balloons are drawn aligned as much as possible horizontally and vertically. Section lines is usually needed to clarify mating parts. Use different section lines styles for adjacent parts. Do NOT draw section lines on sectional view of standard parts such as threaded fasteners, washers, solid shafts, pins, and keys. Example Drawings Exploded Technical Illustration Illustrated parts breakdown 6
General Assembly: 7
Detailed Assembly 8