Sectional views 1SECTIONINGName of the Faculty: Shivraj PuggalUID: 16125E-mail ID:email@example.com
Sectional views 2Issues to be addressed in the unit• Types Sectional viewsa) Full sectionb) Half section• Placement of Section Views• Section Lining – Line Placement• Section Line Mistakes• Section Line Technique
Sectional views 3What is a “Section View” ?• A section view is a view used on a drawing toshow an area or hidden part of an object bycutting away or removing some of that object.• The cut line is called a “cutting plane”, and canbe done in several ways.• The following slides will help show the severalmethods or types of “section views”
Sectional views 4Section ViewsOften there is a need to show interiors that cannot be illustrated clearly byhidden lines. Interiors are shown by slicing through the object resulting incutaway view of the part. Cutaway views are called sectional views, crosssections, or simply sections.
Sectional views 5Full Section• In a full section, the cutting plane linepasses fully through the part.• Normally a view is replaced with the fullsection view.• The section-lined areas are those portionsthat have been in actual contact with thecutting-plane.
Sectional views 9Half Section• Half Section is used to the exterior andinterior of the part in the same view.• The cutting-plane line cuts halfwaythrough the part and removes one quarterof the material.• The line that separates the different types(interior and exterior) may be a centerlineor a visible line.
Sectional views 10Half Sections• In general:– Omit hidden lines from both halves of a halfsection whenever possible– Use a center line to divide the sectioned halfand the unsectioned half
Sectional views 14Section Lining – Line Placement• Lines should never be parallel orperpendicular to the object lines.• If the outline of the object has 45 degreelines, 30 or 60 degree lines should beused.• Assemblies with several parts should belined with varying angle section lines.
Sectional views 15Section Lining – Line Placement
Sectional views 18Cutting Plane Line Style• Cutting lines are thick lines (0.7 mm)• The preferred cutting plane line style ismade up of equal dashes ending inarrowheads– Another style uses alternating long dashesand pairs of short dashes
Sectional views 19Section Line Technique• Uniformly spaced byan interval of about .10”• Uniformly thin, notvarying thickness• Do not run beyondouter edges of thevisible lines• Usually at 45˚ angle
Sectional views 21Broken-Out Sections:Often only a partial section of a view is needed to expose interiorshapes. Such a section, limited by an irregular break line is called abroken-out section.
Sectional views 22Revolved Sections:The shape of a cross section of an object may be shown in thelongitudinal view by means of a revolved section.Revolved sections are made by assuming a plane perpendicular to thecenter line or axis of the object and then revolving the plane 90degrees about a center line at right angles to the axis.
Sectional views 23RemovedSections:A removed section is asection view that is notin direct projectionfrom the viewcontaining the cuttingplane.Removed sectionsshould be labeledSection A-A andSection B-B,corresponding to theletters at the ends ofthe cutting-plane line.Removed sectionsshould be arranged inalphabetical order fromleft to right on thedrawing sheet
Sectional views 24Offset Sections:In sectioning through an irregular object it is often desirable to showfeatures that do not lie in a straight line by offsetting or bending thecutting plane. Such a section is called an offset section.The offsets or bends in the cutting plane are all 90 degrees and arenever shown in the section view.
Sectional views 25Ribs in Sections:To avoid a false impressionof thickness and solidity,ribs, webs, gear teeth, andother similar flat features arenot section lined eventhough the cutting planepasses through the feature.In the example the cuttingplane A-A passes throughthe vertical rib or web butthe rib or web is not sectionlined (figure a).Figure (b) is incorrectbecause it gives a falseimpression of thickness orsolidity.
Sectional views 26Aligned Sections:To include in a section viewcertain angled elements, thecutting plane may be bent topass through those features.The plane and features areimagined to be revolved intothe original plane.In the example the cuttingplane is bent to pass throughthe angled arm and thenrevolved to a vertical position(aligned) from where it isprojected across to thesection view.