Advanced Manufacturing ChoicesMAE 156-256Spring 2012, Dr. Marc MadouClass 9: Rapid Prototyping By Dr. Marc Madou

Two Ways for Fabrication:

Subtractive manufacturingAdditive Manufacturing

Rapid Prototyping Some other names:Additive manufacturingComputer controlled moldless additive manufacturingPart is produced by producing multiple slices i.e. cross sectionsFrom 3D model [STL file (see next slide)] to physical object, with a click Layered manufacturingRapid prototyping:Variety of methods: more and more functional products rather than just prototypes

STL File*The STL (stereo lithography) file format is supported by many other software packages; it is widely used for rapid prototyping and computer-aided manufacturing (CAM). STL files describe only the surface geometry of a three dimensional object without any representation of color, texture or other common CAD model attributes. *An STL file describes a raw unstructured triangulated surface by the unit normal and vertices (ordered by the right-hand rule) of the triangles using a three-dimensional Cartesian coordinate system.

Basic Principles of Rapid PrototypingRapid Prototyping3d model generatedSliced Each slice manufactured and layers are fused togetherA voxel (volumetric pixel or, more correctly, Volumetric Picture Element) is a volume element, representing a value on a regular grid in three dimensional space. This is analogous to a pixel, which represents 2D image data in a bitmap (which is sometimes referred to as a pixmap).

Materials For Rapid PrototypingMaterials covered:Thermoplastics (FDM, SLS)Thermosets (SLA)Powder based composites (3D printing)Metals (EBM, SLS) Sealant tapes (LOM)

Stereolitography (SLA) Selective Laser Sintering (SLS)Fused Deposition Modeling (FDM)Laminated Object Modeling (LOM) 3D Printing Electron Beam Melting (EBM)

Examples of Rapid Prototyping Applications: Prototyping (90 %)Concept modelsArchitectural modelsDisney charactersMoviesor is that real and thus manufactured?EtcManufacturing (10%)Implants and custom medical devicesAerospace partsPilot scale production of lab equipmentMolds .. A Stradivarius ?

Rapid Prototyping by Industry Sectors:

Methods for RPStereolitography (SLA) Selective Laser Sintering (SLS)Fused Deposition Modeling (FDM)Laminated Object Modeling (LOM) 3D Printing Electron Beam Melting (EBM)

Selection of Optimal ProcessFunctional parts:FDM (ABS and nylon)SLS (thermoplastics, metals)EBM (high strength alloys, Ti, stainless steel, CoCr)Non functional parts:SLA: smoothest surface, good for castingLOM, 3D Printing, marketing and concept protos.

Rapid Prototyping Techniques:

Machine Cost Response Time Material Application Fused Deposition Modeler 1600 (FDM) $10/hr 2 weeks ABS or Casting Wax Strong Parts Casting Patterns Laminated Object Manufacturing (LOM) $18/hr 1 week Paper (wood-like) Larger Parts Concept Models Sanders Model Maker 2 (Jet) $3.30/hr 5 weeks Wax Casting Pattern Selective Laser Sintering 2000 (SLS) $44/hr 1 week Polycarbonate TrueForm SandForm light: 100%; margin: 0">Casting Patterns Concept Models Stereolithography 250 (SLA) $33/hr 2 weeks Epoxy Resin (Translucent) Thin walls Durable Models Z402 3-D Modeller (Jet) $27.50/hr 1 week Starch/Wax Concept Models

Process:Laminated Object Modeling (LOM)

Object made by deposition and cutting of layers of tapes Introduced in 1991 by Helisys Inc of Torrance. Cubic and Helisys offer this technologySlow, sharp edgesResearch on composites prepregnated moldless manufacturingInexpensive depending on accuracy, large scale models possibleSlow and inaccurate (knives vs lasers)

LOM Objects

Fused Deposition Modeling (FDM)Extruder on a cartesian robotExtrudes thermoplast polymers spaghetti Moderately fast and inexpensive Stratasys is the market leaderFunctional parts, ABS and nylon Best choice for mechanical engineers and product developers ! Can be used for direct digital manufacturingSystems starting from $14,000

FDM

Abbreviation:FDMMaterial type:Solid (Filaments)Materials:Thermoplastics such as ABS, Polycarbonate, and Polyphenylsulfone; ElastomersMax part size (LxWxH):36.00 x 24.00 x 36.00 in.Min feature size:0.005 in.Min layer thickness:0.0050 in.Accuracy:0.0050 in.Surface finish:RoughBuild speed:Slow

Most common FDM SystemsHigh Res: Dimension ELITE Large FootPrint (12x12)Dimension SST1200 Low cost uPrint ($14,900)Do it Yourself:FAB@HomeRepRap

Stereolitography (SLA) Patented in 19863D System is the market leaderHighest resolution and smoothnessUV Laser beam cure cross-sections of parts in a liquid batch of photoreactive resinSubvariants: DLP entire layer projection

Stereolitography (SLA)

Selective Laser Sintering (SLS)Can be used for both thermoplastics and metalPowder is fed into a continuous layerLaser is used to fuse/sinter powder particles layer-by-layerProduces functional partsLayer thickness 0.004 or less

SLS samples

3D PrintingLayer of powder is first spread across build areaInkjet-like printing of binder over the part cross-sectionRepetition of the process with the next layerCan produce multi-colored partsUseful only for presentation mediaLowest resolution of all techniquesMarket Leader: Z-Corp

3D Printing

Electron Beam Melting (EBM)Dispensed metal powder in layersCross-section molten in a high vacuum with a focused electron beamProcess repeated until part is completedStainless steel, Titanium, Tungsten partsIdeal for medical implants and injection moldsStill very expensive process

Examples of EBM

Do it Yourself FDM rapid prototyping(cost under $5K) FAB@Home RepRap

The Future ? Self-replication !RepRap achieved self-replication at 14:00 hours UTC on 29 May 2008 at Bath University in the UK. The machine that did it - RepRap Version 1.0 Darwin - can be built now - see the Make RepRap Darwin link there or on the left, and for ways to get the bits and pieces you need, see the Obtaining Parts link.

Questions and Answers ?

Rapid Prototyping Process FlowSolid ModellingTesselation/Generation of STL fileSupport GenerationSlicing of the Model Model Physical BuildupCleanup and Post CuringSurface Finishing