Engineering drawing Chapter 6 Section.ppt
- 1. ADAMA SCIENCE AND TECHNOLOGY UNIVERSITY SCHOOL OF MECHANICAL, CHEMICAL AND MATERIAL ENGINEERING DEPARTMENT OF MECHANICAL ENGINEERING ENGINEERING DRAWING ; MEng1102 CHAPTER-6 SECTIONAL VIEWS Date, Jun 2024 05/07/25
- 2. Learning Outcomes At the end of the lesson the students will be able to: •Define Sections and Identify the Necessity of sectional views •List the types of sectioning and differentiate between them •Practice the convention in sectioning •Make practical exercise on both sectional view and pictorial section.
- 3. 6.1. Introduction Sections are used to clarify the interior construction of a part that can not be clearly described by hidden lines in exterior views. By taking an imaginary cut through the object and removing a portion, the inside features may be seen more clearly.
- 4. 6.2.Necessity of sectional views To see clearly interior features of the object. To clarify the interior details of an object that can not be clearly described by hidden lines. To reduce confusion.
- 5. 6.3.Terminology & common practices Basic Terminologies in sectional views Cutting Plane Cutting Plane Line Section Lines
- 6. Cutting plane CUTTING PLANE Cutting plane line Cutting plane is a plane that imaginarily cuts the object to reveal the internal features. Section lines
- 7. Cutting plane line is an edge view of the cutting plane. CUTTING PLANE LINE Indicate the path of cutting plane.
- 8. ANSI standard Thick line Thick line JIS & ISO standard Thin line CUTTING PLANE LINESTYLES Viewing direction Viewing direction Viewing direction
- 9. SECTION LINING Section lines or cross-hatch lines are used to indicate the surfaces that are cut by the cutting plane. Section lines Drawn with 4H pencil.
- 11. SECTION LINES SYMBOLS The section lines are different for each of material’s type. Cast iron, Malleable iron Steel Concrete Sand Wood For practical purpose, the cast iron symbol is used most often for any materials.
- 12. SECTION LINING PRACTICE The spaces between lines may vary from 1.5 mm for small sections to 3 mm for large sections. COMMON MISTAKE
- 13. SECTION LINING PRACTICE It should not be drawn parallel or perpendicular to contour of the view. COMMON MISTAKE
- 14. 6.4.KIND OF SECTIONS 1. Full section 2. Offset section 3. Half section 4. Broken-out section 5. Revolved section (aligned section) 6. Removed section (detailed section)
- 15. FULL SECTION VIEW The view is made by passing the straight cutting plane completely through the part.
- 16. OFFSET SECTION VIEW The view is made by passing the bended cutting plane completely through the part. Do not show the edge views of the cutting plane.
- 17. TREATMENT OF HIDDEN LINES Hidden lines are normally omitted from section views.
- 18. HALF SECTION VIEW The view is made by passing the cutting plane halfway through an object and remove a quarter of it.
- 19. HALF SECTION VIEW A center line is used to separate the sectioned half from the unsectioned half of the view. Hidden line is omitted in unsection half of the view.
- 20. The view is made by passing the cutting plane normal to the viewing direction and removing the portion of an object in front of it. BROKEN-OUT SECTION VIEW
- 21. A break line is used to separate the sectioned portion from the unsectioned portion of the view. BROKEN-OUT SECTION VIEW There is no cutting plane line. Break line is a thin continuous line (4H) and is drawn freehand.
- 22. EXAMPLE : Comparison among several section techniques
- 23. Revolved sections show cross-sectional features of a part. No need for additional orthographic views. This section is especially helpful when a cross-section varies. REVOLVED SECTION VIEW
- 24. REVOLVED SECTION VIEW Basic concept
- 25. REVOLVED SECTION VIEW Basic concept
- 26. Given Step 1 a. Assign position of cutting plane. b. Draw axis of rotation in front view. Steps in construction REVOLVED SECTION VIEW Edge view of Edge view of cross-section cross-section
- 27. Steps in construction Given a. Transfer the depth dimension to the front view. REVOLVED SECTION VIEW Step 2
- 28. Steps in construction Given REVOLVED SECTION VIEW a. Draw the revolved section. Step 3 b. Add section lines.
- 29. Steps in construction Given REVOLVED SECTION VIEW FINAL PICTURE
- 30. Placement of revolved section 1. Superimposed to orthographic view. Superimposed Break 2. Break from orthographic view. REVOLVED SECTION VIEW
- 31. 6. Removed section Removed section is revolved section. Used where space does not enough for revolved section Can be located elsewhere on a drawing with properly labeled REMOVED SECTION VIEW Section view is shown outside the view.
- 32. Example : Revolved vs. removed sections. Revolved section Removed section REMOVED SECTION VIEW
- 33. 6.5.CONVENTIONAL PRACTICE Omit the section lines on the section view of Rib Web Lug if the cutting plane is passed flatwise through. Spoke, if the cutting plane is passed longwise through.
- 34. Rib and Web are thin, flat feature of an object that acts as a structural support. Rib Rib Web
- 35. Rim Spoke is the rod radiating from the hub to the rim of a wheel. Spoke Spoke Rim Hub Hub
- 36. Lug is an ear which is built as portion of an object for attachment.
- 37. EXAMPLE : RIB Normal multiview drawing Normal section view Section view drawing with convention
- 38. EXAMPLE : WEB : flatwise cut Normal multiview drawing Normal section view Section view drawing with convention
- 39. EXAMPLE : WEB : crosswise cut
- 40. EXAMPLE : SPOKE Misleading impression
- 41. EXAMPLE : LUG
- 42. 6.6. Aligned Section Aligned section is a section view that is drawn by imaginary rotating the object’s features appeared in a principal view about symmetry Axis.
- 43. Example : Hole Gives the impression that this holes are at unsymmetrical
- 44. Example : Hole
- 45. Example : Rib
- 46. Example : Ribs & Holes
- 47. Example : Lug
- 48. END