ERT 249 CAD FOR BIOSYSTEMS ENGINEERING

1. ERT 249 CAD FOR BIOSYSTEMS ENGINEERING SECTIONING PREPARED BY: SAMERA BINTI SAMSUDDIN SAH SCHOOL OF BIOPROCESS ENGINEERING

2. Outline

3. Purpose

4. Sectioned Drawings

5. The Cutting Plane

6. The Cutting Plane • Cutting planes may be labeled at their endpoints if multiple cutting plane lines are used • When using multiple cutting planes each sectioned drawing is drawn as if the other cutting plane lines do not exist • The cutting plane line takes precedence over center lines • Occasionally cutting plane lines are not shown when their location is obvious

7. Section Lines • Section lines are drawn where the object passes through the cutting plane • If a saw was used to cut the part then section lines represent the cutting marks left by the saw blade • Different materials may be represented by the use of different section line types • The general section line type which may be used for any material is the line type for iron

8. Section Lines • Section lines should not be parallel or perpendicular to object lines • Section lines are generally drawn at 45 degrees unless this conflicts with other rules • Section lines should be oriented at different angles for separate parts • Occasionally section lines are only drawn on the perimeter of large areas • Section lines are not used for thin parts rather they are filled in solid (Do not use closely spaced section lines)

9. Section Drawing Types • Full Section • Half Section • Assembly Section • Offset Section • Broken-Out Section • Revolved Section • Removed Section • Special Section Conventions

10. Full Section • The cutting plane passes completely through the part as a single flat plane

11. Half Section • The cutting plane only passes half way through the part • The other half is drawn as usual • Hidden lines are not shown on either half of the part • A center line is used to separate the two halves • Mostly used on cylindrical parts

12. Assembly Section • Shows how parts fit together • Different parts have different section line orientation • Different materials use different section line types • Standard parts (shafts, pins, dowels, rivets, screws, washers, gears, etc.) are not sectioned

13. Assembly Section • Cut each part of the assembly and section each part with the appropriate section line type • Put the parts together in their assembled position

14. Assembly Section • The shaft is not sectioned because it is a standard part and section lines would provide no additional information • The other two part are made from the same material • The orientation of section lines clearly shows the location of the different parts

15. Assembly Section • The top and bottom mating part are made from different materials in the part shown below • A center line is added to the shaft to show that it is a circular feature

16. Offset Section • The internal features of many part can not be shown using a single straight cut to create the sectioned drawing • An offset section is used for such parts

17. Offset Section • The multiview drawing is often difficult to interpret when there are several hidden features on the object • A sectioned view makes the object much easier to understand

18. Offset Section • An offset section allows the cutting plane to pass through all of the internal features • There may be several bends in the cutting plane

19. Offset Section • The actual part would show a new visible line at the bend in the cutting plane • Since the cutting plane bend is arbitrary, do not show the line representing this bend in the sectioned drawing

20. Offset Section • The sectioned view does not show the bend in the cutting plane • Hidden lines are not shown • Be sure to include object lines that are behind the cutting plane

21. Broken-Out Section • Only a portion of the view is sectioned • A jagged break line is used to divide the sectioned and unsectioned portion of the drawing

22. Revolved Section • A cross section of the part is revolved 90 degrees and superimposed on the drawing • A jagged break line may be used to divide the revolved section from the rest of the drawing

23. Removed Section • Similar to the revolved section except that the sectioned drawing is not superimposed on the drawing but placed next to it • The view and the cutting plane are labeled (Section A-A) • The removed section may be drawn at a different scale

24. Special Section Conventions • There are special rules (conventions) that are followed to make some parts more understandable • Some features are rotated to their true radial position in sectioned views

25. Special Section Conventions • The object is difficult to understand using standard multiviewdrawings where hidden lines are used to represent internal features

26. Special Section Conventions • If the part is sectioned as it would actually appear if cut the details of the ribs and holes would not be clear • Since the objective is to make the drawing easy to interpret the drawing is modified following standard conventions

27. Special Section Conventions • The cutting plane shows that the features are revolved to their true radial position • Hidden features are not shown • The sectioned drawing produced is a distorted but clearer picture of the object • The section drawing appear as a full section • The arrows show the direction of the view

28. Special Section Conventions • Ribs are not sectioned when the cutting plane passes through them lengthwise • Ribs are sectioned if the cutting plane passes through them at other orientations

29. Special Section Conventions • The front view is replaced by a full section view • The cutting plane shown in the top view shows the direction of the line of sight • The holes and ribs have been revolved to their true radial position • The ribs are not sectioned in this orientation • The section lines are all drawn at the same angle since the object is one solid part

30. Sectioning With Solid Models • Slice • cuts the solid object at the specified cutting plane using the current color • breaks the objects into two parts • one part may be deleted or moved • Section • creates a 2-D drawing of the section • only draws the portion of the object that is cut (i.e. the portion of the object that has section lines)

31. Sectioning With Solid Models • SLICE command • SECTION command

32. Sectioning With AutoCAD • Use BHATCH • Use the correct scale • Default line orientation is 45 degrees • The general line type is ANSI31 • Use different line types for different materials • Use PICK POINTS to select an internal point in the sectioned portion of the drawing

33. THE END...