CAD / CAM
From transcript: 20ME450B CAD (S) · 20ME530 CAD/CAM (B)
Cheat sheet
Formulas
Definitions
- Feature-based CAD
- Holes, pads, patterns as design features
- Parametric / history-based
- Rebuild tree; edit early features carefully
- Direct modeling
- Push/pull faces without history dependence
- BREP / CSG
- Boundary representation / constructive solid geometry
- Assemblies mate
- Constraints: coincident, concentric, offset…
- DFM/DFA
- Design for manufacture / assembly
- Toolpath strategies
- Pocket, contour, adaptive clearing, finishing
- Digital twin
- Virtual model updated with real process data
- Feature-based modeling
- Pads/pockets/patterns with design intent
- Associativity
- Drawing/assembly update when model changes
- Post-processor
- Maps CAM CL data to machine-specific G-code
Topic-wise short notes
3D CAD practice
- Sketch constraints fully defined — stable rebuilds.
- Top-down vs bottom-up assembly strategies.
- Configurations/design tables for families.
- Drawings: projected views, GD&T, revision control.
CAM & toolpaths
- Roughing high MRR; finishing scallop height controls finish.
- 3-axis vs 5-axis — undercuts and tool stickout.
- Simulation: material removal + machine kinematics.
CAD tool craft
- Keyboard shortcuts, templates, material properties for mass/FEA.
- Naming features and packing design files for teams.
Model quality
- Fully define sketches; avoid tiny edges/gaps that break CAM.
- Defeaturing for FEA/CFD exports when needed.
- PMI/MBD: product manufacturing information on 3D model trend.
Exam traps & quick notes
- S in CAD — lead with SolidWorks/Creo portfolio stories.
- GD&T on drawings prevents ambiguous inspection.
- Wind tunnel FYP: Creo sheet metal flats + BOM.
- Model with manufacturing intent: datums, stock, grain, draft.
- Large assemblies: simplify, patterns, lightweight modes.
- CAM: stock definition and workholding first — collisions.
- Verify feeds/speeds from tool library + material.
- Export STEP for interoperability; native for editability.
Comprehensive notes
3D CAD practice
Sketches, mates, configurations, design tables, FEA prep geometry cleanup.
External: SolidWorks help ↗ PTC Creo docs ↗
CAM & toolpaths
2.5D vs 3-axis strategies, stepovers, stock models, verification/simulation.
External: Autodesk CAM learning ↗
Parametric CAD craft
Sketches, constraints, design intent, configurations, mates. Drawing associativity. Export STEP for vendors. My CAD course grade S — lead with SolidWorks/Creo portfolio.
External: NPTEL ↗ Engineering Toolbox ↗
CAM toolpaths
2.5D vs 3-axis; stepovers; stock models; collisions; post-processors map to machine dialect.
External: NPTEL ↗ Engineering Toolbox ↗
Interview Q&A for this subject
Q: What is design intent?
A: Model updates predictably when dimensions change — mates/features reflect how the part should vary.
External: ASQ / quality ↗ MIT OCW ↗