9.3 Fabrication specifications: The several forms of engineering drawings Flashcards
What are layout drawings and what do they show?
Layout drawings:
- Are working drawings
- Show:
- the major parts or components of a device
- relationships between the parts and components
What do detail drawings show?
Detail drawings show:
- the individual parts or components of a device
- relationships between parts/components
What do assembly drawings show?
Assembly drawings show how the individual parts or components of a device fit together.
What type of drawing is shown? Is it drawn with tolerances?
This is a layout drawing. No, it is not drawn with tolerances.
What kind of drawing is shown? Is it drawn with tolerances?
This is a detail drawing. Yes, this detail drawing is drawn with tolerances.
What type of drawing is pictured below? What type of view is used in this drawing?
This is an assembly drawing. The type of view used is an exploded view.
What are tolerances? What do they define?
Tolerances define the permissible ranges of variation in critical or sensitive dimensions.
What do fabrication specification standards articulate?
Standards articulate the best current engineering practices in routine or common design situations.
What do fabrication specification standards indicate?
Fabrication specification standards indicate performance levels that must be met for:
- drawings
- e.g., ASME Yl4.5M-1994 Dimensions and Tolerancing
- the fire safety of buildings built within the United States
- e.g., the Life Safety Code of the National Fire Protection Association
What roles do the American National Standards Institute (ANSI) serve?
The American National Standards Institute (ANSI) serves the following roles:
- a clearinghouse for the individual standards written by professional societies (e.g., ASME, IEEE) and associations (e.g., NFPA, AISC) that govern various phases of design
- the national spokesman for the United States in working with other countries and groups of countries (e.g., the European Union) to ensure compatibility and consistency wherever possible
What are detail drawings used to communicate?
Detail Drawings are used to communicate the details of our design to the manufacturer or machinist.
What is the primary goal of detailed drawings and what system was developed to help achieve the goal?
The principal goal of detail drawings is for the drawings to contain as much information as possible while being both as clear and as uncluttered as possible, such that the details of the design can be unambiguously communicated to manufacturers and/or machinists.
Engineers and machinists have developed the geometric dimensioning and tolerancing (GD&T) system of standard symbols and conventions to meet this goal.
Why was the geometric dimensioning and tolerancing (GD&T) system developed?
The geometric dimensioning and tolerancing (GD&T), a system of standard symbols and conventions was developed because engineers require common standards by which we can communicate our designs to those makers or machinists or fabricators who will actually make or build them.
What essential components must every drawing have to ensure that it is interpreted as intended?
Drawings must have the following essential components to ensure that they are interpreted as intended:
- standard drawing views
- standard symbols (to indicate particular items)
- clear lettering
- clear, steady lines
- appropriate notes (including specifications of materials)
- a title on the drawing
- the designer’s initials
- the date the drawing was created
- dimensions and units
- permissible variations or tolerances
Below is shown an example of a drawing displaying most of the essential components required to ensure correct interpretation. What type of drawing is it? What essential components can you identify?
This is a detail drawing. Note the “essential components” shown in the drawing.
