Basic Principles and Generation of Layer Information

Andrea, Emilia, Sofie, Stephanie

Rapid Prototyping25.10.2012

Basic Principles of Rapid Prototyping Processes

• A generative production process• Layers• 2½ D• Directly from computer data

• Generation of the mathematical layer information• Generation of the physical layer model

The principle of model generation by rapid prototyping

Generation of Layer Information

• Description of the geometry by a 3D data record• Generation of the geometrical information of each layer• Projection of the geometrical layer information of each layer

Description of the geometry by a 3D data record

• Data flow

Modeling 3D-bodies in 3D-CAD

CAD-Model

- Component Geometry- Materials- Surface quality- Production Process- … and much more

CAD Model types

Basic Solids

Surface determinating models

Hybrid models

Design Systematics of 3D-CAD

Common Mistakes

• Surface Model• The normal vector needs to point out of the

component

Common Mistakes• Surface Model• Gaps between surfaces

Demands on CAD systems Some requirements, on the CAD system, should be taken into consideration to realization the principle of simultaneous engineering.

Considerable requirements• Parametric 3D designs

• Hybrid models

• Continuous database

• Redundancy avoidance

• Open system

• Associativity

Reverse engineering

Reverse engineering takes an already existing product and re-defines it into a workable model.

Advantageous measurementThe measurement of an existing geometry is advantageous if one or more of the following work steps dominate the design: • Making of mirror-symmetrical CAD models from hand models that are

never exactly symmetrical • Making of mirror symmetrical CAD models from semi models.• Introduction of additional

geometries such as grooves or drillings in complex components.• Alterations of the model to

enable variations to be probed on the screen, for example.

• Isolation of one element of a group of components as a basisfor further construction work.

Measured Data Logging

Complexity of single geometry

• Are these surfaces geometric basic bodies such as, for example, cubes or cylinders?

• How large is their proportion?• Do the surfaces join each other only evenly or also unevenly?• Do the surfaces meet at obtuse-angled or acute-angled joints?• If the degree of complexity of all single geometrics is

extremely low then the resulting complete model will also possess a low degree of complexity. Such bodies could also be measured completely in the conventional manner.

Generation of Geometrical Layer Information on Single Layers

• Slicing- STL- SLC

STL Format

Practical advantages (STL)

• Easy to solve syntax errors

• Higher quality of geometric information

• Permit any desired scale without reversing into the CAD

SLC Format

Projection of Geometrical Layer Information on the Layer• Vector• Raster• Mask processes

Questions?