2 Rapid prototyping Introduction Subtractive processes Additive process Virtual PrototypingApplications
3 Rapid prototypingTechnology which considerably speeds the iterative product development processFig: a) Examples of parts made by rapid prototyping b) Stereolithography model of cellular phone
4 Advantages CAD data files can be manufactured in hours. Tool for visualization and concept verification.Prototype used in subsequent manufacturing operations to obtain final partTooling for manufacturing operations can be produced
5 Classification of Rapid Prototyping Rapid prototyping is classified to 3-major groupsSubtractive ( Removal of material )Additive ( Adding of material )Virtual ( Advanced computer base visualization)
6 Subtractive ProcessSubtractive process use computer based Prototype technology to speed the processEssential Technologies for subtractive prototyping :Computer – based drafting packages ( 3-D representation of parts)Interpretation software (Translation of cad file to manufacturing software)Manufacturing Software (Planning Machining operations)Computer-Numerical Control Machinery
7 Additive ProcessBuild parts in layer by layer (slice by slice as stacking a loaf of bread)Fig: The computational steps in producing a stereolithography file a) Three dimensional description of part b)The part is divides into slices (only one in 10 is shown) c)support material is planned d)A set of tool directions is determined to manufacture each slice. Shown is the extruder path at section A-A from c) For a fused-deposition-modeling operation
8 Additive Process Require elaborate software 1 : Obtain cad file 2 : Computer then constructs slices of a 3-dimensional part3 : slice analyzed and compiled to provide the rapid prototyping machine4 : setup of the proper unattended and provide rough part after few hours5 : Finishing operations and sanding and painting6:labor intensive and production time varies from few minutes to few hours
9 Fused Deposition Modeling A gantry robot controlled extruder head moves in two principle directions over a tableTable can be raised or lowered as neededThermo plastic or wax filament is extruded through the small orifice of heated dieInitial layer placed on a foam foundation with a constant rateExtruder head follows a predetermined path from the fileAfter first layer the table is lowered and subsequent layers are formedFig : (a)Fused-deposition-modeling process. (b)The FDM 5000, a fused-decomposition-modeling-machine.
10 Fused Deposition Modeling Fig: a)A part with protruding section which requires support material b) Common support structures used in rapid-prototyping machines
11 Fig :Stereolithiography Process Works based on the principle of curing liquid photomer into specific shapeA vat which can be lowered and raised filled with photocurable liquid acrylate polymerLaser generating U-V beam is focused in x-y directionsThe beam cures the portion of photo polymer and produces a solid bodyThis process is repeated till the level b is reached as shown in the figureNow the plat form is lowered by distance abThen another portion of the cylinder is shaped till the portion is reachedFig :Stereolithiography Process
12 Selective laser sintering (SLS) : Fig: The selective laser sintering process
13 Selective laser sintering SLS based on sintering of nonmetallic powders onto a selective individual objectsBasic elements in this process are bottom of processing chambers equipped with 2 cylindersPowder feed cylinder which is raised incrementally to supply powder to part-build cylinder through a roller mechanismPart-build cylinder which is lowered incrementally to where the sintered part is formed.
14 Selective laser sintering Set of the proper computer files and the initiation of the production processesMachine operate unattended and provide rough part after few hoursFinishing operations as sanding and paintingLabor intensive & production time varies from few minutes to few hours
15 Selective laser sintering Layer of powder is first deposited on part build cylindersA laser beam controlled by instruction from 3-D file is focused on that layer tracing & sintering a particular cross-section into a solid mass & dust is taken off.Another layer of powder is now deposited this cycle is repeated again and dust is shaken off
16 Fig:The solid based curing process Solid Base curing :Also called Solid ground curingEntire slices of part are manufactured at one timeSo large throughput is achievedMost expensive & time consumingThe entire process is shownFig:The solid based curing process
17 Ballistic Particle Manufacturing Stream of material , such as plastic ,ceramic, metal or wax ejected through small orifice at a surfaceMechanism similar to inkjet mechanism ( piezo-electric pump)Operation repeats similar to other process to form a part with layers of wax deposited on top of each otherInk jet heat guided by three-axis robot
18 Fig:Three dimensional printing process 3-D Printing processSimilar to ballistic particle manufacturingFig:Three dimensional printing process
19 3-D Printing process Print head deposits an inorganic binder material Binder directed onto a layer of ceramic metal powderA piston supporting the powder bed is lower incrementally with each step a layer is deposited and unified by binderCommonly used materials – Aluminum oxide, silicon carbide,silica and zirconium.Common part produced by 3-D printing is a ceramic casting shallCuring around 150 C – 300 FFiring – 1000 C – 1500 C
20 Laminated object manufacturing (LOM ) Laminated implies laying down of layers which are adhesively bonded to one anotherUses layer of paper or plastic sheets with heat activated glue on one side of the product partsExcess material to be removed manuallySimplified by preparing the laser to burn perforations in cross-sectional patternLOM uses sheets as thin as 0.05mmCompressed paper has appearance and strength of soft wood , and often mistaken for elaborate wood carvings.
21 Laminated Object Material (LOM) Fig : (a) Laminated object-manufacturing process (b)Crankshaft-part example made by LOM
22 Virtual prototypingVirtual prototyping (modeling and simulation of all aspects of a prototype, i.e. mechanical design, kinematics, dynamics, and controls accompanied by a realistic visualization).Realizing the best design in the shortest lead-time of complex products/processesAllows the exotic, unconventional designs be prototyped, rapidly and cost-effectively
23 Applications of Rapid Prototyping Production of individual partsProduction of tooling by Rapid Prototyping (Rapid Tooling)Fig: Manufacturing steps for investment casting that uses rapid prototyped wax parts as blanks.
24 Rapid ToolingThe term Rapid Tooling (RT) is typically used to describe a process which either uses a Rapid Prototyping (RP) model as a pattern to create a mold quickly or uses the Rapid Prototyping process directly to fabricate a tool for a limited volume of prototypes .a)Tooling time is much shorter than for a conventional tool. Typically, time to first articles is below one-fifth that of conventional tooling.b) Tooling cost is much less than for a conventional tool. Cost can be below five percent of conventional tooling cost.c) Tool life is considerably less than for a conventional tool.d) Tolerances are wider than for a conventional tool.
25 Rapid ToolingFig: Manufacturing steps in sand casting that causes that uses rapid-prototyped patterns
26 Rapid ToolingFig: Manufacturing steps in sand casting that causes that uses rapid-prototyped patterns