1.2 Sections and Hatching

Section: Goal (2) and Characteristics (2)

• Reveal internal details (bores, threads, grooves)

• Dimension hidden/internal elements

• Section plances become section lines

• Intersection area of section plane and workpiece is hatched.

Hatching: Properties (5)

• Narrow, full lines

• 45° angle wrt to relevant body contour/symmetry line

• Spacing between lines constant

• A part has the same hatching in every view (same direction, without turning or modifying when rotating the view)

• Different parts have different hatching patterns (hatching, angle and spacing)

Section Types and when are they allowed (3)

• Full section: normal section, arrow projection

• Half-section: allowed only for rotationally symmetrical components

• Part-section: only allowed if sectioned part is dimensioned elsewhere

Sections: Rules (5)

• Arrow projection always applied

• A section does not replace a view

• No sections between projected views

• Half- and part-sections are allowed within views (they are views)

• Section is placed on drawing in the direction of the arrows

How is the cutting line of sections cuts and the notation? (3)

• Broad, dashed-dotted with overlap with the component

• Section arrow (30° apex)

• Captial letters for marking, line group 0,5, dimension font size 3.5 mm, section letter 5 mm

What are the characteristics of a cutting line with parallel offset planes? (4)

• Broad dashed-dotted with overlap.

• Arrows with 30° apex

• Broad full lines at kinks

• No edge at kinks in the section cut

What are the characteristics of an angled cutting line? (3)

• Broad, dashed-dotted with overlap

• Only for rotationally symmetrical parts

• Section view drawn as if the section lies in one plane

What are the characteristics of the section cut with cutting line partly outside the component?

• Broad, dashed-dotted with overlap

• Full broad line at the kinks

• Intersection of the section line with the outer boundary of the component with solid broad line.

What can be done if there is no space for the section view in the direction of the arrows?

Additional notation with direction of rotation and angle of rotation can be added.

Which components have special representations in section views? (5)

• Ribs

• Shafts, bolts, screws (long, circular, rotational parts) in longitudinal sections

• Teeth of gear wheels and racks

• Profile cross sections

• Bores

Why is the representation of Ribs in section cuts an special case?

The interior of Ribs in longitudinal sections is not shown.

Why is the representation of Shafts, Bolts, Screws etc in section cuts an special case?

Shaft, bolts, screws are not shown in longitudinal sections

Why is the representation of gear Teeth in section cuts an special case?

Teeth are not shown in sections of wheels and racks

Why is the representation of Bores in section cuts an special case?

Bores of rotation-symmetrical parts can be rotated around the axis of symmetry of the part in the section plane without addtional specifications

Why is the representation of Profile Cross-sections cuts an special case?

Cross-sections can be displayed rotated and hatched in the view

Why is the cross-section of drive shafts special?

Cross-section of drive shafts and similar can be placed direct underneath with symmetry lines connecting both.

What is particular in this case?

• Partial section shown in not sectioned half-section

What happens with narrow profile cross-sections? (2)

They are drawn completely in black. Many narrow profiles together are to be drawn with a small gap between them.

What happens with large section areas? (1)

Only edges are hatched