When a product or environment has been designed, it is then prototyped or produced by a manufacturer or constructed by a team of builders or engineers. To assist in the creation of the product a set of plans are required. These plans enable the people whose job it is to create the design to do so in a way that meets the designer or client requirements. In order to do this, a drawing method that can illustrate to someone the size and shape of product's form, how many parts the product has and from what material each part or component will be made or constructed from is required.
What drawings are needed?
When a designer chooses to have a product manufactured they must provide the manufacturer or builder with enough information to make each individual part and assemble the parts to construct the overall product or environment. In these circumstances a complete set of 'Working Drawings' are needed. A set of working drawings consist of 'Detail Drawings' and 'Assembly Drawings'. In some occasions a 3-dimensional pictorial drawing can also be included to provide additional information if required.
Detail drawings are used as a primary reference for manufacturing an individual part. They must show all of the detail required to manufacture an individual component including a suitable number of fully dimensioned orthogonal views. It is convention for detailed drawings to contain only one part per drawing sheet; however, multi-detailed drawings can be used when it is more convenient to show a small number of simple individual parts on the same drawing.
The following information is included on a detail drawing;
- Dimensions and instructional annotations
- Drafting standards used (AS 1100)
- Name and Title of the Drawing
- Drawing NumberUnit of measure (mm)
- Tolerances where appropriate
- Surface texture finishes
- Special Treatments (heat, metallic coatings, paint)
- References that reference a part to its particular sub-assembly
- Type of Material used (Steel, High Speed Steel, Aluminium, Copper, Brass, Polystyrene, ABS)
- Names of drafter, checker, approver, the dates on which the drafting and other procedures occurred
- Zone reference system to help locate areas on a drawing
- Size of the drawing sheetName of company or department
- Drawing sheet reference, eg. 1 of 2
Assembly and Sub-assembly Drawings
An Assembly drawing shows how all the individual parts fit together to make an assembly. They are drawn using an arrangement of orthogonal views and cut sections. To show how large complex parts are assembled, large assembly drawings are generally made up of smaller sub-assembly drawings. In the case of a mountain bike for example, the bike's frame would be considered a sub-assemble, the gear cogs and chain considered a separate sub-assembly and so on. All of these sub-assemblies would then assemble to form the finished mountain bike assembly.
There are two styles of assembly drawings used; General Assembly Drawings and Working Assembly Drawings
General Assembly Drawings
General assembly drawings are orthogonal drawings that are used to identify the individual components required to make up an assembly or sub-assembly. When drawing a general assembly the following points should be taken into account;
Only the necessary views required to clearly describe how the parts fit together and how the sub-assembly functions should be shown. These views should include a sectional view to avoid the use of hidden lines.
Annotations and dimensions that relate to the function of the sub-assembly are provided.
Individual components are identified by the use of leaders from the part and numbers enclosed within circles or balloons.
A Parts list sorted by the part number in the drawing identifies each part, its drawing number, and quantity. This list should also include any off the shelf parts used within the sub-assembly.
Assembly and sub-assembly drawings do not need to list information about the manufacture of individual parts. However, information about how a sub-assembly is to be assembled or important dimensions that could affect its assembly can be included.
Working Assembly Drawings
Working assembly drawings are a combination of working drawings and assembly drawings. They are typically only used where the drawing of the individual components, dimensions and the assembly of parts can be drawn on the same drawing sheet without ambiguity. Such drawings are typically only used in industries like furniture design where join details are provided in enlarged separate detailed drawings.