Computer Aided Manufacture
Computer Aided Manufacture
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When a design moves from CAD modelling to manufacturing, the digital model must be prepared so that machines such as 3D printers, CNC machines and laser cutters can interpret the data correctly.
This preparation process ensures the model contains the correct geometry, manufacturing information and reference data required to produce the component accurately.
Designers and production engineers must therefore manipulate the model, communicate surface finish requirements, define datums, and gather information such as volume, centre of mass and model mass before production begins.
3D Model Manipulation for CAM
3D Model Manipulation for CAM
3D model manipulation is the process of preparing a CAD model so it can be used in manufacturing systems (CAM).During this process, the CAD model is converted into a format that the manufacturing machine can understand and used to generate tool paths or printing instructions.
For example:
For example:
- A model may be converted to STL for 3D printing
- A drawing may be converted to DXF for laser cutting
Important considerations when preparing a model
Important considerations when preparing a model
- The model must be converted to a suitable file format for the manufacturing machine.
- The model must be scaled correctly to match the build volume of the machine.
- The model must be orientated correctly to improve print quality and reduce support material.
- Support structures or meshes may need to be added to prevent collapse during printing.
- The model must be produced within tolerance so the manufactured part is the correct size.
- The correct materials and manufacturing settings must be selected.
Surface Finish
Surface Finish
Surface finish describes the texture and quality of the surface of a manufactured component.Different manufacturing processes produce different surface finishes, and in some cases a specific finish may be required for the part to function correctly.Surface finish requirements are often specified on orthographic drawings, alongside dimensions and tolerances.
Surface finish must be controlled because it can affect:
Surface finish is defined by three main characteristics:Lay
The direction of the surface pattern created during manufacturing.Surface Roughness
The small irregularities left on a surface by the manufacturing process.Waviness
Larger irregularities caused by machine vibration or distortion during manufacture.
Why surface finishes are required:
Surface finish must be controlled because it can affect:Why surface finishes are required:
- how parts fit together
- the appearance of the product
- the performance and durability of the component
- the amount of friction between surfaces
Characteristics:
Surface finish is defined by three main characteristics:LayCharacteristics:
The direction of the surface pattern created during manufacturing.Surface Roughness
The small irregularities left on a surface by the manufacturing process.Waviness
Larger irregularities caused by machine vibration or distortion during manufacture.
Datums
Datums
A datum is a theoretical reference point, axis or plane used to measure and manufacture a component.It provides a fixed reference position from which all other dimensions and tolerances are taken.
No surface is perfectly flat or accurate. Datums provide a consistent starting point for measurement, ensuring the part can be produced accurately.Datums help ensure:
Why it is required:
No surface is perfectly flat or accurate. Datums provide a consistent starting point for measurement, ensuring the part can be produced accurately.Datums help ensure:Why it is required:
- parts are aligned correctly during manufacturing
- dimensions are measured consistently
- components fit together correctly during assembly
Volume
Volume
Volume is the total space occupied by the 3D model.CAD software can automatically calculate the volume of a model once it has been created.
Volume information is important during manufacturing because it helps engineers to:
Why it is used:
Volume information is important during manufacturing because it helps engineers to:Why it is used:
- check the model fits within the build volume of a 3D printer
- determine how much material will be required
- estimate manufacturing costs
- ensure enough printing material is available
Centre of Mass
Centre of Mass
The centre of mass (or centre of gravity) is the point where the mass of an object is evenly balanced.This point can be calculated automatically by CAD software.
During manufacturing the centre of mass helps engineers to:
Why it is required:
During manufacturing the centre of mass helps engineers to:Why it is required:
- determine whether the model is stable during production
- identify areas that may require support structures
- ensure the model does not collapse or topple during printing
Model Mass
Model Mass
Model mass represents the total weight of the object, based on the model’s volume and the material used.CAD software can calculate this automatically when a material is assigned to the model.
Knowing the model mass helps engineers to:
Why it is required:
Knowing the model mass helps engineers to:Why it is required:
- estimate the amount of material required
- calculate manufacturing costs
- reduce material waste
- ensure the component will perform correctly in use
3D Printing Setup
3D Printing Setup
Before a 3D model can be produced using additive manufacturing, the digital model must be prepared and configured for the specific 3D printer and material being used.This setup process ensures the printer has all the information required to successfully build the object layer by layer. Incorrect setup can lead to failed prints, weak structures or poor surface quality.
3D printers cannot interpret CAD models directly. The model must be prepared so the printer understands:
Why it is required:
3D printers cannot interpret CAD models directly. The model must be prepared so the printer understands:Why it is required:
- the shape of the object
- the layers required to build it
- the materials and temperatures needed
- the support structures required during printing
Key 3D Printing Setup Requirements:
Key 3D Printing Setup Requirements:
- Convert the Model to STL
- Scale the Model
- a model that is too large for the printer
- incorrect dimensions in the finished component
- Model Orientation
- improve surface finish
- reduce support material
- increase print strength
- reduce print time
- Structural Supports
- printing overhanging sections
- preventing thin structures collapsing
- improving print stability
- Print Speed and Surface Quality
- improve surface quality
- increase accuracy
- Material Selection
- strength
- flexibility
- temperature resistance
- Printer Temperature Settings
- Nozzle temperature – ensures filament melts correctly
- Print bed temperature – helps the model adhere to the bed and prevents warping
- Centre of Mass and Stability
- topple during printing
- require additional support structures
Environmental Considerations for 3D Printing
Environmental Considerations for 3D Printing
3D printing can also be configured to reduce environmental impact.Methods include:
- Using recycled or sustainable printing materials
- Recycling unused or failed prints
- Optimising models to use minimal material while maintaining strength
- Selecting appropriate print quality settings to avoid unnecessary material use
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