1. Layered Manufacturing

2. How can we make physical form? Additive Subtractive Deformation

3. Additive Process Add materials bit by bit Less material wastage Usually need a mould Casting

4. Subtractive Process Remove un-needed material from stock Waste material Usually need only cutting tools Milling, Sculpting

5. Deformation Process Deform stock material Less material wastage Limited form, need many different tools Bending, kneading Sometimes called Net-Shape Manufacturing

6. Layered Manufacturing Additive process in nature No mould required No special tools One machine, unlimited forms

7. Basic process

8. Prepare CAD model Slice model virtually into layers Produce the bottom most (or top most) layer according to the layer profile On top of (or beneath) the produced layer, add subsequent layer Loop until completion

9. Freedom of LM Undercut Hollow Jig and fixture not required

10. Advantage of LM Reduce operator intervention Easy to learn Time and cost only related to size, not complexity

11. Disadvantage of LM Time and cost only related to size, not complexity Limited choice of material Double approximation of the form, first during polygonization and then by slicing

12. Common use of LM Rapid Prototyping One-of-a-kind manufacturing Art sculpting Medical modelling Architectural modelling

13. Shape implications in LM Overhang Cliffs Holes Slicing errors

14. Exercise

15. Rapid prototyping process Polygon model creation Model verification Pre-processing  Orienting and positioning  Support generation (optional)  Slicing Building Post-processing

16. Rapid prototyping process

17. Data input Almost all RP systems rely on STL A polygon model format ASCII and Binary With normal vectors Implicit unit Can be generated from all major applications One file can contain multiple components

18. Data Input

19. An ASCII STL file

20. Model verification LM can deal with only non-manifold polygon models  Check for ‘leakage’  Check for naked edges  Check for holes  Check for reversed facets  Check for model obscurities

21. Model obscurities Crossed facets Overlapping facets Degenerated facets

22. Source of manifold errors

23. LM Errors caused by bad STL Delaminate due to double facets Reversed normals Ill-behaved CAD translators

24. Verification applications Major polygon modelling applications  RapidForm, Surfacer, GeoMagics, etc. Specific STL applciatons  Magics  SolidViews

25. Function of verification applications Check and repair model errors Rotate and section model to facilitate error correction Merge and separate components Move, rotate, and scale models Checking dimensions Advanced editing

26. Fill holes by adding facets Add draft angle Shelling and hollowing Smoothing and re-sampling

27. Pre-processing Done by equipment specific applications Move, rotate, and scale models Some contain basic STL repair functions Some contain support generation and edit functions Slicing STL and generating equipment control code

28. Supports

29. Position and size of model Machine specific, usually lower left corner as the origin Position and size can be verify in pre- processing application Built-specific errors (beam width, thread width, growth, etc.) compensated by application Shrinkage, form and fit, etc. compensated by operators

30. Building process SLAClear EpoxyNon-critical products EOSNylon / Steel‘Usable’ products FDMABSFunctional prototypes 3DPPlasterConcept prototypes ThermojetWaxConcept prototypes

31. Post-processing Draining and rinsing Support removal Post-curing and heat-treating Surface finishing