SECTIONAL DRAWING REQUIREMENTS

Sectional Drawing Requirements - In order to indicate the inner details of a machine part, the article is presupposed to be cut by a cutting plane and therefore the section is viewed when the removal of cut portion. Sections ar created by at cutting planes and ar selected by capital letters and therefore the direction of viewing is indicated by arrow marks.

Hatching Of Sections

Hatching is a technique for highlighting portions of a piece. The most basic kind of hatching is often suitable for the goal, and it can be as simple as continuous thin lines (type B) at a convenient angle, preferably 45°, to the main outlines or symmetry lines of the sections.

Fig. 1 Preferred Hatching Angles

Separate portions of the same component's section must be hatched in the same way. The hatching of adjacent components must be done in opposite orientations or at different spacings (Fig.2a). Hatching may be limited to a zone, following the contour of the hatched region, in the event of huge expanses (Fig.2b).

Fig. 2 Hatching Of Adjacent Components

When sections of the same part are depicted side by side in parallel planes, the hatching must be identical  but the sections may be offset along the dividing line (Fig. 3). When it is impossible to place inscriptions outside the hatched region, hatching should be interrupted (Fig. 4).

Fig. 3 Sectioning Along Two Parallel Planes

Fig. 4 Hatching Interrupted For Dimensioning

Cutting Planes

A type H line should be used to identify the cutting plane(s). Capital letters should be used to identify the cutting plane, and arrows should be used to indicate the viewing direction. The relevant designation should be used to designate the section.

Fig. 5 Cutting Plane Indication

Ribs, fasteners, shafts, wheel spokes, and other similar items are not cut in longitudinal sections and should not be hatched.

Fig. 6 Section Not To Be Hatched

Figures 7 and 8 show sectioning in two parallel planes and three continuous planes, respectively.

Fig. 7

Fig. 8

Sectioning into two intersecting planes, one of which is rotated onto the projection plane, as shown in Fig. 9.

Fig. 9

Parts of revolution with regularly spaced details that need to be presented in section but are not in the cutting plane can be depicted by rotating them into the cutting plane.

Fig. 10 

Revolved or Removed Section

Cross sections can be rotated or removed in the appropriate view. The outline of the section should be shown with continuous thin lines when rotated in the relevant view.

Fig. 11 Revolved Section

When the section was removed, the outline should be drawn with continuous thick lines. The removed section can be placed near the view and linked to it with a chain thin line (Fig. 2a), or it can be placed in a different location and identified in the conventional way (Fig. 2b).

Fig. 12 Removed Section

Half Section

Symmetrical parts may be drawn, half in plain view and half in section.

Fig. 13 Half Section

Local Section

If a half or complete section is not feasible, a local section can be drawn. A continuous thin free hand line can be used to represent the local break.

Fig. 14 Local Section

Arrangement of Successive Section

Successive sections can be put above or below the cutting planes, with designations for both cutting planes and sections (Fig. 15)

Fig. 15 Successive Section