Detailed Theory of Sectioning in Engineering Drawing:
Sectioning is a technique used in engineering drawing to reveal the internal details of a complex object by cutting it along a specified plane. This helps in understanding the internal features that are otherwise hidden in external views. Sectioning is crucial in manufacturing, design, and assembly processes.
Detailed Theory of Sectioning i.e. Full, Half, Offset, Revolved & Broken Section: https://youtu.be/XpBhh1dywuI
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Types of Sectioning:
1. Full Section
A full section is created when the object is completely cut through along a specified plane. The portion of the object in front of the cutting plane is removed, revealing the internal features.
Use: Used when all internal details of an object need to be shown clearly.
Example: Cylindrical shafts with keyways, machine components like gears and bearings.
2. Half Section
A half section is created when the object is cut into two equal halves, but only one half is sectioned while the other half remains as an external view.
Use: Used for symmetrical objects to show both external and internal features.
Example: Bearings, pulleys, symmetrical machine parts.
3. Offset Section
In an offset section, the cutting plane is bent at different angles to pass through important internal features, which are then projected as a straight section.
Use: Used for objects where important internal details do not lie on a single plane.
Example: Complex castings, connecting rods, machine components with multiple holes.
4. Revolved Section
A revolved section is created by rotating a cut-out cross-section of an object and placing it within the same view.
Use: Used for thin parts like arms, ribs, and spokes, where the section needs to be shown within the external view itself.
Example: Crankshafts, spokes of wheels, brackets.
5. Broken Section
A broken section is used when only a small portion of the object needs to be sectioned to reveal internal details while keeping the rest of the object intact.
Use: Used when a small internal portion of an object needs to be shown without drawing a full section.
Example: Long shafts, screws, bolts, and fasteners.
Sectioning Conventions
Hatching or Section Lines: These lines represent the solid material cut by the plane and are drawn at 45° inclination (except for special cases).
Cutting Plane Representation: Shown using thick dashed lines with arrows indicating the viewing direction.
Hidden Details Removed: In sectional views, hidden lines are usually omitted to avoid confusion.
Applications of Sectioning
Understanding internal mechanisms of machines and components.
Simplifying assembly drawings in manufacturing and design.
Reducing complexity in multi-view drawings.
Enhancing clarity in blueprint readings for engineers and technicians.