Lines, Linetypes And Their Use In Technical Drawing

In technical drawing, all the elements inside it have standards. With these standards, the other person reads that technical drawing can understand the object and features of it. Also, lines have important standards in technical drawing. Here we show you the general standards of technical drawing. 

Technical Drawing with Engineering Graphics

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Linetypes And Weight Standards In Technical Drawing

  • Thick and visible line: These lines are used for the main lengths of the object view. In general application, thick lines are 0.6 mm(.024”). 
  • Thin hidden lines: Thin hidden lines are used as intermittent line types. Thin lines are nearly 0.3 mm(.012”) in most technical drawings. They are used for showing the geometrical features hidden behind the main lines. 
  • Thin section lines: The difference between the thin section lines form the hidden lines, that they are continuous. They are used for showing the internal sections such as holes etc. in section planes. The thickness of the thin section lines same as the hidden lines. Thin section lines are shown with red arrows below. 
  • Centerlines:  Centerlines are used to show the centers of the round elements such as circles or semi-circles. This is a special line type with 0.3 mm thickness. 
  • Dimension and extension lines: These lines are used for showing the lengths and dimensional features of the geometric features on technical drawings. They are generally used as thin lines. Consider thin lines are 0.3 mm and thick lines 0.6 mm in technical drawing.
  • Leaders and arrows: In technical drawings, the standards of the leaders and arrows are very important. You can see the general standards that are used generally below. 
  • Cutting plane lines: Cutting plane lines are used to show where the section plane is taken on the part. Cutting plane lines are intermittent and thick. You can see the general standards for the cutting plane lines below.


These are the general line types and their uses in mechanical technical drawing.

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Source of last two images: FREDERICK E. GIESECKE, SHAWNA LOCKHART, Technical Drawing With Engineering Graphics 15th Ed., Pearson, Pg.35





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