TG - 3D/2D CAD Commands Flashcards
What is a library of parts?
- Collection of standard parts commonly used for assemblies
- Nuts, screws, bolts, etc
What are 3 benefits of a library of parts?
- Saves time as CAD designer doesn’t need to model standard parts
- Ensures standard parts are consistent with international standards
- Allows manufacturers to understand what standard components are required
What are 5 advantages to 2D CAD over manual drawing?
- Quicker and more accurate production
- Easier to edit/change
- Repetitive elements can easily be imported via library
- New designs can be built off existing designs
- Drawings can easily be scaled
What are 5 disadvantages of CAD compared to manual drawing?
- Start-up and maintenance costs
- Continual need to upgrade systems to remain competitive
- Risks of viruses/crashes preventing work
- Power-cuts preventing work
- Staff training costs
What are 5 advantages of 3D CAD over physical modelling?
- Cheaper to model and test than physical model
- Easy to edit and change with changing design
- No need to source materials/resources
- Animation allows designer to see how parts interact
- More quick to create and more accurate
Lists 2 different arrays
- Radial array
- Rectangular array
What are 2 common files used when importing/exporting CAD models?
- STL
- IGES
Name 6 different CAD constraints and their purpose
- Concentric: aligns two circles
- Parallel: puts two lines in parallel
- Tangent: makes a line touch a circle
- Coincidental: fixes a line to a particular point
- Collinear: causes lines/ellipses to fall on a certain line
- Perpendicular: puts a line at 90 degrees to another
What is surface modelling?
- Directly changes the surface of a wire model
- Adds curves, contours or other elements to a flat surface
- Works in squares or polygons
- Does not provide solid properties, such as weight or centre of mass
What is an extrusion along a path?
- A path is defined and then a profile is defined on a plane perpendicular to the path
- The profile is then extruded along the defined path
What is morphing?
- Pulling or distorting a model using ‘handles’ to form a new shape
- Similar to surface modelling but with 3D CAD
- Typically used for more natural shapes
What are irregular fillets/chamfers?
- Where the chamfer/fillet changes in depth/radius throughout the edge
- Fillets create curves, chamfers create flat faces
What is a loft?
- Links two or more sketches together to create a 3D shape
- Can be edited and pulled to create various shapes
- Typically used for irregular geometry which can’t be achieved with extrusions/revolves
What is blending?
- Similar to a chamfer/fillet
- Connects two 2D/3D sketches/objects smoothly or with a consistent curve
- Effectively ‘blends’ two shapes together
- Either a tangent or a curve blend (3rd or 5th degree spline)
Where is the plan in third angle projection?
Above the elevation
Where is the plan in first angle projection?
Below the elevation
Is the trapezium to the left or right of the circle in first angle projection?
Left
What does CFD stand for?
Computational fluid dynamics
What does FEA stand for?
Finite element analysis
What is CFD used for?
- Analysing how air, water, or other fluids interact with a project
- Highlights points of pressure on design
- Shows if vortexes are forming and where within the product
What is FEA used for?
- Analyses how a product reacts to forces and pressures within a virtual environment
- Shows high points of stress and can estimate the breaking point for various materials/joints
What are 3 benefits of CFD?
- Instantaneously yields data that is useful for improving the design
- Cost effective
- Effectively locates where vents, heaters and other air-flow machines can be placed
What are 3 benefits of FEA?
- Much less expensive than testing and potentially breaking real-life models/components
- Can easily be altered and re-tested in a short amount of time
- Colours give a clear and precise idea of how the product reacts to forces
What is mechanical animation?
- Create a simulation of 3D CAD models moving to represent assemblies, components or products and how they interact with each other
- Helps to show efficiency of product
- Helps to make clients understand how the product is going to look
List 5 different CAM machines
- 3D printer
- Lathe
- Router
- Laser cutter
- Milling machine
What are 5 different elements that FEA tests?
- Mechanical stress and vibration
- Fatigue
- Motion
- Heat transfer
- Fluid low
What is a roughing process used for in CAM?
- Roughly cuts out the model
- Gets rid of excess materials
- Typically large cuts taken in a zig-zag manner
What is a semi-finishing process used for in CAM?
- Works from a roughed product and takes it to a nicer finish
- Middle stages are usually required for difficult materials to process
- Uses raster passes and pencil millings
What is a finishing process used for in CAM?
- Final cuts to make a smooth and high-quality finish
- Much more slow than semi-finishing or roughing due to time taken for quality
What is contour milling?
- Milling which achieves a much higher quality finish
- Not only moves the tool on 4-axis but can also rotate, hence using a 5-axis tool
How can we calculate the mass/centre of mass/volume of a model for CAM?
- Using CAD software packages
- Input material used and rough weight of 1 cm^3 of said material and the software will run a calculation for you
Why is COM/mass/volume important in CAM processes?
- Manufacturing engineers need to check whether the mass of a product is within a CAM machines’ limits
