5.6 CAD/CAM

5.6 CAD/CAM

1. Principles and Benefits

1. CAD (Computer-Aided Design):

   • Definition: Use of computer systems for design creation/modification.

   • Core Functions:

     • Geometric modeling (2D/3D).

     • Engineering analysis (FEA, CFD).

     • Documentation (drawings, BOM).

     • Design optimization.

   • Model Types:

     • Wireframe (lines/curves).

     • Surface (skin only).

     • Solid (complete volume).

2. CAM (Computer-Aided Manufacturing):

   • Definition: Use of computer systems for manufacturing planning/control.

   • Core Functions:

     • Process planning.

     • NC programming.

     • Tool path generation.

     • Machine tool control.

3. CAD/CAM Integration:

   • Principle: Seamless data flow from design to manufacturing.

   • Data Exchange: Using standards (IGES, STEP, DXF).

   • Workflow: Design → Analysis → NC Code → Manufacturing.

4. Benefits:

   • Design Benefits:

     • Faster design cycles.

     • Improved design accuracy.

     • Easy modifications.

     • Better visualization.

   • Manufacturing Benefits:

     • Reduced lead times.

     • Higher quality consistency.

     • Lower prototype costs.

     • Optimized tool paths.

   • Overall Benefits:

     • Increased productivity.

     • Reduced errors/scrap.

     • Better documentation.

     • Enhanced collaboration.

2. Additive Manufacturing

1. Definition: Building objects layer-by-layer from digital models.

2. Basic Process:

   • 3D model slicing into layers.

   • Material deposition layer by layer.

   • Bonding between layers.

   • Post-processing if required.

3. Key Technologies:

   • FDM (Fused Deposition Modeling):

     • Thermoplastic filament extruded.

     • Common materials: ABS, PLA.

     • Low cost, widely available.

   • SLA (Stereolithography):

     • UV laser cures liquid resin.

     • High accuracy, smooth finish.

     • Used for prototypes, molds.

   • SLS (Selective Laser Sintering):

     • Laser sinters powder particles.

     • No support structures needed.

     • Functional parts possible.

   • SLM/DMLS (Metal Printing):

     • Metal powder melted by laser.

     • Fully dense metal parts.

     • Aerospace, medical applications.

4. Advantages:

   • Complex geometries possible.

   • No tooling required.

   • Customization easy.

   • Reduced material waste.

   • Rapid design iterations.

5. Limitations:

   • Lower production speed.

   • Limited material choices.

   • Surface finish limitations.

   • Post-processing often needed.

   • Higher cost for mass production.

3. Rapid Prototyping

1. Definition: Quickly fabricating physical models from CAD data.

2. Purpose:

   • Design verification.

   • Functional testing.

   • Assembly checking.

   • Marketing/sales samples.

3. Process Chain:

   • CAD model creation.

   • STL file generation.

   • Model slicing.

   • Layer fabrication.

   • Post-processing.

4. Technologies Used:

   • All additive manufacturing methods.

   • CNC machining for prototypes.

   • Vacuum casting for multiple copies.

5. Applications:

   • Concept models.

   • Fit and function testing.

   • Investment casting patterns.

   • Medical models (surgical planning).

6. Benefits:

   • Reduced time to market.

   • Early error detection.

   • Better design validation.

   • Cost savings in development.

4. CNC and Flexible Manufacturing Systems

1. CNC (Computer Numerical Control):

   • Definition: Automated control of machine tools via programmed commands.

   • Components:

     • Controller (computer).

     • Drive system (motors).

     • Feedback system (encoders).

     • Machine tool.

   • Programming:

     • G-code (standard language).

     • M-code (miscellaneous functions).

     • CAD/CAM generated programs.

   • Advantages:

     • High accuracy/repeatability.

     • Complex shapes possible.

     • Reduced operator skill required.

     • Higher productivity.

   • CNC Machines:

     • CNC lathes/milling machines.

     • CNC routers.

     • CNC grinders.

     • Multi-axis machining centers.

2. Flexible Manufacturing Systems (FMS):

   • Definition: Automated production system with flexibility.

   • Components:

     • CNC machines.

     • Material handling system (AGVs, conveyors).

     • Central computer control.

     • Automated storage/retrieval.

   • Flexibility Types:

     • Machine flexibility (different operations).

     • Process flexibility (different sequences).

     • Product flexibility (different products).

     • Volume flexibility (different quantities).

   • Layout Types:

     • Progressive layout (line).

     • Loop layout (circular).

     • Ladder layout (branching).

     • Open field layout (grid).

   • Benefits:

     • Reduced setup times.

     • Better machine utilization.

     • Quick response to changes.

     • Lower inventory levels.

   • Challenges:

     • High initial investment.

     • Complex programming/control.

     • Maintenance requirements.

     • Need for skilled personnel.

3. Integration Levels:

   • Standalone CNC machines.

   • DNC (Direct Numerical Control) systems.

   • Full FMS with automated integration.

   • CIM (Computer Integrated Manufacturing).