Friday, August 10, 2007

A complete set of Manufacturing drawings

Manufacturing drawings are way of communication designs as document design solutions and production information. It is also a blueprint which requires being sufficiently complete and accurate. The drawing must be consisted of, detail drawing, assembly drawing – sectioned assembly, part numbers, drawing numbers, title blocks, part list, part identification, revision block, scale specification, tolerance specification, and engineering change orders.
Detail drawing is a dimensioned, multi view drawing of single part, describes shape, size, material, and finish. It could strictly to ANSI standard or the standard for specific company, for lettering, dimensioning, assigning part numbers, notes, tolerances, etc. For assembly, standard parts such as threaded fasteners, brushing, and bearing are not drawn as a detail, but are shown in the assembly view. Standard parts are not drawn as details because they are not normally for manufactured. The details are normally drawn on the sheet as the same scale, also, incase there are more than one detail is placed in the sheet, the spacing between details are carefully planed, including leaving sufficient room for dimensions and notes.
Assembly drawing is showing how each part put together. If the design depicted is only part of the total assembly, it is referred to as a sub-assembly. Assembly drawing is normally consisted of, all the parts, part list, trail number, and operation. All the parts will be drawn in their operating position. Part list or bill of materials is the showing of the detail number for each part. The single assembly needs quantity, description or name of the part, the catalog number for each part, and the company part number. Detail number is the order and key to the list of part in the part list, these are led by leader lines with balloons. Machining and assembly operations and critical dimensions related to functions. There is also other assembly which is sectioned assembly. Sectioned assembly gives a general graphic description of the interior shape by passing a cutting plane through all. Section assembly is normally convened by standard parts such as fasteners dowels, pin, gear, socket, etc. Next is adjacent part which are lines at different angles, using symbol to describe. The third is thin part, such as gasket, are drawn in solid black.
Part numbers is a string of number coded in a way that company can keep accurate record of its products for better recognition and maintenance. For example, big product that consisted of five hundred pieces need to be well organized to find the right piece.
Drawing number is a standard system that set by each company that can be separated in various criteria such as sequential numbers, combination of number and letters, sheet sizes, number of part in the assembly, model numbers, function, etc. These number normally located on the lower right-hand corner of the drawing sheet in the bottom of the title block.
Title blocks are used for recording all the important information necessary for drawing. It normally located in the lower right corner of the sheet. There is also the standard format such as ANSI standard. A continuation title is used for multi-sheet drawings and does not contain as much detail as title block on the first sheet.
Parts list is a set of working drawings that consist of part list. According to ANSI standard, it located above the title block, and additional part list may be located at the left of and adjacent to the original block. A part list must include a minimum amount of necessary information; name of part, detail number, part material, and number of times that part is used in the assembly, the company-assigned part number, and other information such as weight, stock size, etc.
Parts identifications are identified by leader line that arrow point to the part. Leader line has a balloon showing the part detail number. The balloon is approximately four times the height of the number.
Revision block occur because of changing of design, tool, customer request, error, etc. An accreted must be recorded and should contain date, name if person making the change, description of the change, the change number, and approval. The information is placed in revision block which is normally in the upper right corner of the drawing.
Scale specification is used on the set of drawing must be placed on the title block. If more than one scale is used, the scale must be shown near the detail drawing. Scales are indicated in metric drawing by a colon or equal sign.
Tolerance specification is used for dimensions that are not specifically tolerance; a general tolerance note is used. This note is placed in the lower right corner near the title block. For example, one-place decimal inches ±.1 or two-place decimal millimeters ± 0.51.
Engineering change order will be made after the design has been analyzed for avoiding error. To make a change in a design most industries require use of an engineering change notice or engineering change order. There are requirements for the common features; identification of what has to be change in the form of part numbers, part names, and drawing numbers, an explanation of need, a list of all documents and departments, description of changes, approval by project manager, instruction to the change’s implement, etc.
Detail drawing, assembly drawing – sectioned assembly, part numbers, drawing numbers, title blocks, part list, part identification, revision block, scale specification, tolerance specification, and engineering change orders are the fulfilled part to make the drawing complete with necessary information for manufacturing. It is a standard way of communication through an international system.

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