Sectional, assembly & exploded views
Graphic Communication · Higher · mrkellydt.co.uk
What you're learning in this topic
Learning intention WALT
We are learning about sectional, assembly & exploded views, specifically to:
know
- full, half, part, revolved, removed and stepped sections and cut-aways
understand
- good and poor practice in an exploded view
be able to
- read and draw a sectional view with a labelled cutting plane
- apply hatching correctly, leaving webs, shafts, nuts and bolts unhatched
Success criteria WILF
- I can read and draw a sectional view with a labelled cutting plane
- I can apply hatching correctly, leaving webs, shafts, nuts and bolts unhatched
- I can describe good and poor practice in an exploded view
- I can recognise full, half, part, revolved, removed and stepped sections and cut-aways
Sectional views
A sectional view shows the inside of an object as if it has been cut through along a cutting plane. The cutting plane is shown on another view with arrows for the viewing direction and letters, and the section is labelled SECTION A–A.
- Hatching: thin lines at 45°, evenly spaced, on the cut surfaces only.
- Different parts in an assembly are hatched in different directions or spacings; the same part keeps the same hatching everywhere.
- Not hatched when cut along their length: webs and ribs, shafts, nuts, bolts, screws, washers, pins, keys and threads.
- Hidden detail is usually left out of sectional views.
Types of section HIGHER
- Full section: cut right through.
- Part (broken-out) section: a small area cut away to show one feature, bounded by a wavy line.
- Revolved section: the cross-section rotated 90° and drawn on the view itself, e.g. the shape of a spoke or arm.
- Stepped (offset) section: the cutting plane changes direction to pass through several features.
- Cut-away: a pictorial with part removed to reveal the inside.
- Sectioned exploded view: an exploded view with parts sectioned.
Assembly drawings
An assembly drawing shows how components fit together, often as orthographic views with a section. In the assignment it must be accurate with no overlaps or gaps, views related and correctly orientated, and sections taken where the task says.
Exploded views
An exploded view pulls the parts of an assembly apart along their assembly lines. A good exploded view has:
- parts in the correct order of assembly;
- parts aligned along the axis they assemble on, often with a centre line or "trail";
- even spacing, so no parts overlap and every part can be seen;
- parts labelled or numbered to match a parts list.
Exam questions show an exploded view and ask for examples of good or poor practice: look for overlapping parts, misalignment, wrong order or hidden parts.
Design challenge: assembly instructions
The brief. A flat-pack stool needs a one-page instruction sheet.
- Plan the sheet.
- Describe how it guides the user.
What a good answer includes
- Numbered stages, each in a box.
- The parts needed shown next to each stage.
- An exploded view with parts in order of assembly, aligned on their axes, evenly spaced, none hidden.
Key terms
| Hatching | Thin 45° lines on cut surfaces of a sectional view. |
|---|---|
| Which parts are not hatched? | Webs, ribs, shafts, nuts, bolts, screws, washers, pins and threads cut lengthways. |
| SECTION A–A | The label for the view taken at cutting plane A–A. |
| Good exploded view | Correct order, aligned, evenly spaced, no overlaps, all parts visible. |
| Revolved section | Cross-section rotated 90° and drawn on the view. |
| Stepped section | The cutting plane changes direction to cut through several features. |
| Part section | A small cut-away area, bounded by a wavy line, to show one feature. |
Quick check
1. Which of these is NOT hatched when cut lengthways?
- A casing
- A base plate
- A bolt
- A housing
Show answer
2. Hatching lines are normally drawn at…
- 30°
- 90°
- 60°
- 45°
Show answer
3. Which is a feature of a good exploded view?
- Parts are aligned along assembly lines
- Parts overlap to save space on the page
- Parts are shown in any order that fits
- Hidden detail is shown on every part
Show answer
4. A section where the cutting plane changes direction is a…
- Full section
- Stepped section
- Revolved section
- Part section
Show answer
5. A cross-section rotated 90° on the view itself is a…
- Part section
- Full section
- Revolved section
- Cut-away
Show answer
Printable worksheet
An I do, we do, you do worksheet for this topic, with a separate answer sheet.