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cessed or attachment bolts of those to be removed, and to provide detail information on components dis-
assembled for repair. Finally, the technician needs to accurately discern the correct alignment of com-
ponents upon reassembly.
Customers who deal with consumer products such as electronic goods will also normally require the
use of exploded CAD drawings to help in understanding the relationships among assembled parts. Ex-
ploded drawings are indispensable for a number of manufacturing industries. While generating assem-
bly drawings, critical interference checks are included to ensure that the entire assembly is integrated,
thus saving a tremendous amount of time and costs in the prototyping phase.
Computer-aided drafting has proved to be a huge timesaver when an assembly drawing is being
produced. Today, there are a large number of sophisticated CAD programs and equipments, and the
vast majority of manufacturers now use these programs to recover high initial production costs. Although
many assembly drawings do not require dimensions, overall dimensions and distances between the
centers or from part to part of the different pieces to clarify the relationship of the parts with each other
can be included. Most important, however, an assembly drawing should be easy to read and not be over-
loaded with detail.
Utilizing CAD programs likewise allows individual component details to be merged together to cre-
ate an assembly or working drawing of the component(s). With CAD systems, three-dimensional (3-D)
models can be created that makes it possible to superimpose images and to graphically measure clear-
ances. When parts have been designed or drawn incorrectly, the errors will often stand out so that ap-
propriate correction can be made. This improves the efficiency of the drafter and helps to make the de-
tails in the final print accurate and the resultant parts function properly.
Information normally required for general assembly drawings includes:
- Parts to be drawn in their operating position
- Part list (or bill of materials) including item number, descriptive name, material, and quantity re-
quired per unit of machine - Leader lines with balloons drawn around part numbers
- Machining and assembly operations and critical dimensions related to the operation of the ma-
chine
Steps in creating an assembly drawing include the following:
- Analyze the geometry and dimensions of the various parts in order to understand the assembly
steps and overall shape of the object. - Select an appropriate view of the object.
- Choose the major components—components that require assembly of several parts.
- Draw a view of the major components according to a selected viewing direction.
- Add detail views of the remaining components at their working positions.
- Add balloons, notes, and dimensions as required.
- Create a bill of materials (BOM).
Assembly drawings can require one, two, three, or more views, although they should be kept to the
minimum necessary. A good viewing direction should be chosen that represents all (or most) of the parts
assembled in their working position.