In an assembly drawing, the various components or items which make up the assembly need to be referenced. In the vice assembly drawing in Figure 3.1, the individual items are shown by the 'balloon' reference system using the numbers 1-10 (in this case). For convenience the balloon item references are normally arranged in horizontal or vertical alignments. The small circles surrounding each number are optional. The standard that gives details of item references is ISO 6433:1981.
The list of items appropriate to the assembly drawing of the vice is shown in Figure 3.1. In this case three columns are shown, the item reference (part number) the number of each component required in the assembly (number of) and the description of the item. In this case there are three columns of information. Other columns can be added as appropriate. Examples of other columns are: material, stock number, delivery date, remarks and relevant ISO standards.
The vertical sequence of the item entries should be in numerical order. When the item list is included on the assembly drawing as in Figure 3.1, the items should read from bottom to top in numerical order with the column headings at the very bottom. However, if the item list is on a separate drawing, on its own, the sequence is to be from top to bottom with the headings at the top. The standard that gives details of item lists is ISO 7573:1983.
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