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Line Type and Weight
Line type and line weight provide valuable information to the print reader.
For example, line type and weight can answer the following questions.
- Is the feature visible or hidden from view?
- Is the line part of the object or part of a dimension?
- Is the line indicating symmetry?
There are four commonly used line types;
- continuous
- hidden
- center
- phantom
Some lines are more important than others. Importance is indicated by line weight or thickness. The thicker the line, the more important it is.
Line types
Visible lines
- Visible lines represent visible edges and boundaries.
- Continuous and thick (0.5 - 0.6 mm).
Hidden lines
- Hidden lines represent hidden edges and boundaries.
- Dashed and medium thick (0.35 - 0.45 mm).
Center lines
- Center lines Represent axes of symmetry.
- Long dash – short dash and thin (0.3 mm).
Phantom lines
- Phantom lines are used to indicate imaginary features such as alternate positions of moving parts and adjacent positions of related parts.
- The line type is long dash – short dash – short dash and the line weight is usually thin (0.3 mm).
Dimension and Extension lines
- Dimension and extension lines are used to show the size of an object. In general, a dimension line is placed between two extension lines and is terminated by arrowheads, which indicates the direction and extent of the dimension.
- The line type is continuous and the line weight is thin (0.3 mm).
Cutting plane lines
- Cutting plane lines are used to show where an imaginary cut has been made through the object in order to view interior features.
- The line type is phantom and the line weight is very thick (0.6 to 0.8 mm).
- Arrows are placed at both ends of the cutting plane line to indicate the direction of sight.
Section lines
- Section lines are used to show areas that have been cut by the cutting plane.
- Section lines are grouped in parallel line patterns and usually drawn at a 45o angle.
- The line type is usually continuous and the line weight is thin (0.3 mm).
Break lines
- Break lines are used to show imaginary breaks in objects.
- A break line is usually made up of a series of connecting arcs.
- The line type is continuous and the line weight is usually thick (0.5 – 0.6 mm).
