Engineering Design and Material Selection Lecture 3: Technical Drawings PDF

Engineering Design and Material Selection Lecture 3 — Technical Drawings: Projections and Cuts Dr. Tino Stankovic Prof. Dr. Kristina Shea Prof. Kristina Shea 1  Course Schedule Week/ Topic...

Engineering Design and Material Selection Lecture 3 — Technical Drawings: Projections and Cuts Dr. Tino Stankovic Prof. Dr. Kristina Shea Prof. Kristina Shea 1  Course Schedule Week/ Topic Case study Quiz Lecturer Dates 1 Introduction and Sketching 2 Introducing Engineering Design Health Prof. Dr. Kristina Shea 3 Technical Drawing: Projections and Cuts 4 CAD: Introduction and Modeling Operations 5 CAD: Features and Parametric Modeling Future Mobility 6 CAD: Freeform Modeling Dr. Tino Stankovic 7 CAD: Assemblies and Standard Mechanical Parts X (45 min) 8 Technical Drawing: Dimensioning Health 9 Sustainability in Engineering Design 10 Materials and their Properties 11 Manufacturing Processes with Focus on Additive Manufacturing Sustainable Materials Prof. Dr. Kristina Shea 12 Material Selection 13 Review and Q+A X (75 min) Prof. Kristina Shea Engineering Design + Computing Laboratory 2  Learning Objectives ▪ Learn why technical drawings are essential in product development. ▪ Learn the main components of a technical drawing. ▪ Be able to select an appropriate principal view and arrange the drawing. ▪ Be able to select the needed section and detail views and draw them. ▪ Imagine the 3D shape of an object from its technical drawing. Prof. Kristina Shea Engineering Design + Computing Laboratory 3  Views Parallel projections Orthogonal (or orthographic) projection Isometric projection a:b:c=1:1:1  =  = 30° Dimetric Projection Most commonly: a:b:c=1:1:1/2 =42° =7° Trimetric Projection a:b:c=free 30°≤≤45° ≤30° Prof. Kristina Shea Engineering Design + Computing Laboratory 4  3D Model of a Mechanical Ventilator Prof. Kristina Shea Engineering Design + Computing Laboratory 5  Why Do We Need Technical Drawings? ▪ How can we communicate the details of a complex design? ▪ How can we provide manufacturing instructions? ▪ How can we specify requirements for testing and inspection? ▪ How can we enable maintenance and service over time? Prof. Kristina Shea Engineering Design + Computing Laboratory 6  Use of Technical Drawings in Product Development Communication Manufacturing Testing and Inspection Maintenance and Service Prof. Kristina Shea Engineering Design + Computing Laboratory 7  Technical Drawings Key Components ▪ Technical drawings store all relevant information relative to a part and assembly ▪ They are a set of rules and common practices for a “universal language” that is language independent (ISO Norms) Complete Unambiguous Readable Consistent National norms: SN = Swiss Norm Prof. Kristina Shea Engineering Design + Computing Laboratory 8  Technical Drawings Main Shaft Prof. Kristina Shea Engineering Design + Computing Laboratory 9  Main Types of Views Orthogonal Projections Detail Views Sections Prof. Kristina Shea Engineering Design + Computing Laboratory 11  Line Types ▪ Continuous wide line: Visible outlines and edges, lines of reference arrows ▪ Continuous narrow line: Contour edges, hatching ▪ Continuous narrow free-hand line (zigzag line in drawings made in CAD): Break line: Termination of partial or interrupted views (if limit is not a centerline) ▪ Dashed narrow line: Hidden outlines and edges ▪ Long-dashed dotted narrow line: Center lines, lines of symmetry ▪ Long-dashed double-dotted narrow line: Outlines of adjacent parts ▪ Long-dashed dotted narrow line, but wide at ends and at direction changes: Indication of section planes Prof. Kristina Shea Engineering Design + Computing Laboratory 12  Technical Drawing: Process 1. Choose the principal view 2. Choose other required views and cuts 3. Draw the views and cuts 4. Add dimensions (Lecture 8) 5. Verify Prof. Kristina Shea Engineering Design + Computing Laboratory 13  First Example: Cover Plate Prof. Kristina Shea Engineering Design + Computing Laboratory 14  Cover Plate: Which View Should Be The Principal View? A B D C Prof. Kristina Shea Engineering Design + Computing Laboratory 15  First Angle Projection Method Principal view Prof. Kristina Shea Engineering Design + Computing Laboratory 16  First Angle Projection Method Principal view Prof. Kristina Shea Engineering Design + Computing Laboratory 17  Arranging Views: First Angle Projection Method Prof. Kristina Shea Engineering Design + Computing Laboratory 18  Third Angle Projection Method Principal view Prof. Kristina Shea Engineering Design + Computing Laboratory 19  Arranging Views: Third Angle Projection Method Prof. Kristina Shea Engineering Design + Computing Laboratory 20  Selecting Views: Use The Fewest Views Needed Prof. Kristina Shea Engineering Design + Computing Laboratory 21  Arranging Projections Prof. Kristina Shea Engineering Design + Computing Laboratory 23  Cover Plate: Which Additional Views Are Needed? → This does not define the geometry completely Prof. Kristina Shea Engineering Design + Computing Laboratory 24  Better Solution: Section View ▪ Shows geometry “through” the part ▪ Shows features from the back side Cutting Plane Prof. Kristina Shea Engineering Design + Computing Laboratory 25  Final Result Prof. Kristina Shea Engineering Design + Computing Laboratory 26  Tips for Choosing Projected Views ▪ The most informative view is used as the principal view ▪ All details have to be shown in a technical drawing ▪ The object has to be represented without ambiguity ▪ The number of views should be limited to the minimum necessary: ▪ By reasonable choice of views ▪ By using partial and special views ▪ Unnecessary repetition of details should be avoided Prof. Kristina Shea Engineering Design + Computing Laboratory 27  Cuts and Sections Hatching Center line Hidden line Labisch, S., & Weber, C. (2017). Technisches Zeichnen. Wiesbaden: Springer Fachmedien Wiesbaden, https://doi.org/10.1007/978-3-8348-9892-0 Prof. Kristina Shea Engineering Design + Computing Laboratory 28  General Representation Rules II Reference Arrow Center line Cutting Plane Section Cutting Line Prof. Kristina Shea Engineering Design + Computing Laboratory 29  General Representation Rules II Prof. Kristina Shea Engineering Design + Computing Laboratory 30  4.4.2 Schnittarten Grundsätzlich unterscheidet man Vollschnitte, Halbschnitte und Teilschnitte, siehe Bild 4-23. Während beim Vollschnitt das betreffende Bauteil komplett durchgeschnitten ist, zeigt der Halbschnitt sowohl Schnitt als auch Ansicht. Ein Teilschnitt, auch Ausbruch genannt, legt die TypesInnenkonturen of Sections eines Bauteiles nur in bestimmten ausgewählten Bereichen im Schnitt frei. Aus- brüche werden durch so genannte Bruchlinien, das sind schmale Freihandlinien, begrenzt. Bild 4-23 Vollschnitt, Halbschnitt, Teilschnitt (hier Ausbruch) Labisch, S., & Weber, C. (2017). Technisches Zeichnen. Wiesbaden: Springer Fachmedien Wiesbaden, https://doi.org/10.1007/978-3-8348-9892-0 Prof. Kristina Shea Engineering Design + Computing Laboratory 31  4.4.2 Schnittarten Grundsätzlich unterscheidet man Vollschnitte, Halbschnitte und Teilschnitte, siehe Bild 4-23. Während beim Vollschnitt das betreffende Bauteil komplett durchgeschnitten ist, zeigt der Halbschnitt sowohl Schnitt als auch Ansicht. Ein Teilschnitt, auch Ausbruch genannt, legt die TypesInnenkonturen of Sections eines Bauteiles nur in bestimmten ausgewählten Bereichen im Schnitt frei. Aus- brüche werden durch so genannte Bruchlinien, das sind schmale Freihandlinien, begrenzt. Full Section Half Section Local Section Bild 4-23 Vollschnitt, Halbschnitt, Teilschnitt (hier Ausbruch) Labisch, S., & Weber, C. (2017). Technisches Zeichnen. Wiesbaden: Springer Fachmedien Wiesbaden, https://doi.org/10.1007/978-3-8348-9892-0 Prof. Kristina Shea Engineering Design + Computing Laboratory 32  Two adjacent parts Hatching 45° angle to part (different spacing) A A-A Offset A Prof. Kristina Shea Engineering Design + Computing Laboratory 33  Choice of Cuts Taper pin Prof. Kristina Shea Engineering Design + Computing Laboratory 34  45° Choice of Cuts Not hatched Partial Cutting plane Hatching in opposite directions Prof. Kristina Shea Engineering Design + Computing Laboratory 35  Second Example: Motor Holding Plate Prof. Kristina Shea Engineering Design + Computing Laboratory 36  Motor Holding Plate: Which View Should Be the Principal View? A E C B D Prof. Kristina Shea Engineering Design + Computing Laboratory 37  Motor Holding Plate: Possible Orthogonal Projections → Does not define the geometry completely Prof. Kristina Shea Engineering Design + Computing Laboratory 38  Showing What is Inside: Hidden Lines ▪ Hidden lines are dashed lines showing edges not present on the visible face ▪ Only suited for very simple geometries Prof. Kristina Shea Engineering Design + Computing Laboratory 39  Showing What Is Inside: Cuts and Sections A-A B-B C-C (not shown) Prof. Kristina Shea Engineering Design + Computing Laboratory 40  More Complex Cutting Planes Are Possible Prof. Kristina Shea Engineering Design + Computing Laboratory 41  Tips for Sections ▪ Cuts and sections allow insights into parts and assemblies to illustrate hidden geometries ▪ Cuts and sections have to be drawn and annotated unambiguously ▪ Cuts are almost always needed when there are holes in parts ▪ To avoid complex cuts, local sections can be used Prof. Kristina Shea Engineering Design + Computing Laboratory 42  Final Drawing (Dimensioning covered in Lecture 8.) Prof. Kristina Shea Engineering Design + Computing Laboratory 43  Final Drawing Prof. Kristina Shea Engineering Design + Computing Laboratory 44  D CB A Question: Which Section Cut is Shown? D C B A Prof. Kristina Shea Engineering Design + Computing Laboratory 48  Checklist for Verifying Your Technical Drawings Here are some questions that can guide you in verifying the quality of technical drawings: ▪ Is the principal view the most informative view? ▪ Are there sufficient views (projections and cuts) to fully define the geometry? ▪ Are the smaller details clearly visible? ▪ Are the views positioned correctly? ▪ Are the proportions and the scale correct? ▪ Are you satisfied with it? Prof. Kristina Shea Engineering Design + Computing Laboratory 49  Reading Technical Drawings: From 2D Back To 3D ▪ Which 3D model is represented in the drawing below? A B Prof. Kristina Shea Engineering Design + Computing Laboratory 50  Projections and Cuts: Wrap-Up Technical drawings store all relevant information relative to a part and assembly. They are created following sets of rules, norms and best practices. The most informative view is used as the principal view. Only add as many views as needed to unambiguously draw the part and assembly. Sections are important to define what is inside a part or assembly (Lecture 7). Prof. Kristina Shea Engineering Design + Computing Laboratory 51  Exercise 3: Projections and Cuts + CAD Intro What is the isometric view of the Given the 3D model, can you make the cut projections below? below in CAD? Prof. Kristina Shea Engineering Design + Computing Laboratory 52