Graphic Expression and CAD
A technical idea that exists only in the head of the person who had it cannot be manufactured. It needs to be communicated through drawings: from a quick sketch to a standardised drawing that any workshop can interpret without asking questions, and from a diagram that explains how a system works to a digital model that a machine can cut.
Sketch, draft and standardised drawing
Not every graphic representation has the same purpose: some are for thinking quickly and others for manufacturing without errors.
Explain the difference between a freehand sketch, a working sketch and a standard engineering drawing, and indicate at what point in a technical project each one is used.
Explain the difference between a freehand sketch, a working sketch and a standard engineering drawing, and indicate at what point in a technical project each one is used.
Give two advantages of making an initial freehand sketch and two advantages of modelling afterwards with CAD software, and indicate at what point in the design process…
Give two advantages of making an initial freehand sketch and two advantages of modelling afterwards with CAD software, and indicate at what point in the design process you would use each one.
A development team must urgently redesign the ergonomic housing of a portable power tool to reduce weight and improve motor ventilation. The team leader proposes…
A development team must urgently redesign the ergonomic housing of a portable power tool to reduce weight and improve motor ventilation. The team leader proposes skipping the freehand sketching phase and starting directly by modeling 3D solids in CAD to 'save time and send the files to be machined as soon as possible'.
Critically evaluate this proposal:
- a) Justify why forcing the immediate jump to CAD modeling usually makes the project more expensive and restricts the search for optimal solutions in products with organic geometries or anatomical interaction.
- b) Identify at what exact technical milestone in the design process the dimensioned sketch ceases to be sufficient and becomes an unacceptable source of risk for manufacturing (consider finite element thermal analysis, housing fit tolerances, and injection mold manufacturing).
Views, scale and dimensioning
A solid part cannot be fully understood from a single point of view: you need several standardised projections, drawn to a known scale and with their real measurements shown.
Explain what the front view, plan view and side view of a part are, and why a technical drawing usually includes all three views instead of just one.
Explain what the front view, plan view and side view of a part are, and why a technical drawing usually includes all three views instead of just one.
A drawing is drawn to a scale of 1:10. Explain what this means and calculate how long a real edge of $60\ \text{mm}$ measures on the drawing.
A drawing is drawn to a scale of 1:10. Explain what this means and calculate how long a real edge of $60\ \text{mm}$ measures on the drawing.
What is dimensioning a drawing? Name the elements of a dimension (dimension line, projection lines, arrowheads/ends, and dimension value) and explain why the value must…
What is dimensioning a drawing? Name the elements of a dimension (dimension line, projection lines, arrowheads/ends, and dimension value) and explain why the value must be the real measurement of the part and not that of the drawing.
Functional block diagrams
As well as the shape of parts, we need to represent how a system works: which parts it is made up of and what flows between them.
Explain what a functional block diagram is and what it is used for. What does each block represent, and what do the arrows connecting them represent?
Explain what a functional block diagram is and what it is used for. What does each block represent, and what do the arrows connecting them represent?
The figure shows the functional block diagram of a sound system, but one of the blocks is covered with a question mark, as shown in the figure. Indicate which block is…
The figure shows the functional block diagram of a sound system, but one of the blocks is covered with a question mark, as shown in the figure.
Indicate which block is missing and explain what function it performs within the system, taking into account how the signal changes as it passes through it.
A garden irrigation system has this functional diagram: timer → solenoid valve → spray heads; additionally, a rain sensor can override the irrigation. Today it did not…
A garden irrigation system has this functional diagram: timer → solenoid valve → spray heads; additionally, a rain sensor can override the irrigation. Today it did not water at its scheduled time. Order the checks you would carry out on each block (from most likely to least likely) and justify this diagnostic order.
CAD, CAE and CAM
The computer is not only for drawing: it allows you to design in 3D, simulate the behaviour of a part and directly generate the instructions to manufacture it.
Explain what the acronyms CAD, CAE and CAM stand for, what is done with each type of tool, and in what order they are used throughout product development, from idea to…
Explain what the acronyms CAD, CAE and CAM stand for, what is done with each type of tool, and in what order they are used throughout product development, from idea to manufacturing.
STL and STEP files are used to exchange 3D models. Explain what each type contains (a triangle mesh versus the exact geometry of the solid) and reason which one you…
STL and STEP files are used to exchange 3D models. Explain what each type contains (a triangle mesh versus the exact geometry of the solid) and reason which one you would use to send a part for printing and which one to keep editing it in another CAD program.
CAE tools allow simulating a part before manufacturing it. Give an example of a design decision that might change after viewing a stress simulation (reinforcing an area,…
CAE tools allow simulating a part before manufacturing it. Give an example of a design decision that might change after viewing a stress simulation (reinforcing an area, thinning another) and explain what is saved through this virtual check (broken prototypes, material, time).