Section Lining

Section lining is a method of representing internal features of an object in an engineering drawing. This technique involves the use of parallel lines drawn at a 45-degree angle to the object being depicted, with section lining of adjacent features drawn in the opposite direction. Avoid aligning section lines with features and edges. Section lining should be spaced about 1.5 mm apart at a minimum.

The purpose of section lining is to distinguish the internal features of the object from its external features. They indicate where material has been “cut” to show interior features. This is especially useful in situations where the internal features are critical to the functionality of the object or where multiple parts are being assembled together.

ASME Y14.3 describes sectional view drawings in detail.

See also: Cutting Plane Line

Section lining shows where materials would have been removed had the object been cut along the cutting plane line.