Principles Of Additive Manufacturing

Principles Of Additive ManufacturingAdditive manufacturing (AM) is a general term for all technologies that modernise wears by floor addition of material at the micron level, to achieve the required shape, besides of metal removal technique which is traditional subtractive attend to. During research period, AM the floor by tier manufacturing terminology has been standardised by the Ameri shadower society for testing and materials (ASTM) committee F42 on additive bottom technologies.In the beginning AM technologies were restricted because of commonly accepted leading name Rapid prototyping (RP) for the fruition of separates and prototypes, which was the term use for many age to describe all layer additive manufacturing do byes. Advancement in the material, deal and organisation hardw ar cle ard that the parts could be manufactured with an adequate automatonlike property to let for further applications. This allowed the production of end use models with layer additive t echnologies, so rapid manufacturing (RM) was adopted which distinguish the functional nature of the models ca-cad from the prior(prenominal) RP parts and prototypes. lately AM is used generally and RM and RP are only use to illustrate the particular application of AM technologies.1.2.1 Principles of Additive ManufacturingAM technologies execute models by f apply, sintering or polymerisation of materials in predetermined layers with no needs of tools. AM makes possible the manufacture of complex geometries including internal part detail that are approximately not possible to manufacture using machining and moulding routinees, because process does not require predetermined tool paths, draft angles and under cuts.In AM the layers of a model are formed by slicing CAD data with professional software. All AM system work on the equal principle however, layer thickness depend upon parameters and motorcar being used and thickness of layer range from 10m up to 200m. stratums are clear ly visible on the part surface in AM operation, which controls the character of final product. The relation between thickness of layer and surface druthers is known as staircase effect. However, thinner the layer is the durable the processing time and full(prenominal)er the part resolution.Layers in AM are make up at the top of the previous one in z axis. After layer gets touch on the work platform is dropped down by the superstar layer thickness in z axis and the fresh material layer is recoated differently for number of other orders. In resin based system traversing bump into flatten the resin, in powder based system deposited powder is spread using roller or wiper arm, in some system the material is deposited finished a nozzle which deposits the required material. Because recoating time is even longer than the layer processing time. For that sake multiple parts are classing together in the time of adept material recoating build. Different softwares are available to localize and orient part so that maximum number of parts fundament be built together. Available softwares are VISCAM RP and Smart Space used in MAGICS.Some delicate parts produced through AM technologies need a bide structure to hold the part in work platform during the build process. All AM railcar uses different yield structure that are intentional from specific material for effective use of build parts. Commonly used support structures are thin small pointed teeth to minimising the part contact so that they arsehole be remote easily with the hand tools.1.3 Rapid PrototypingRapid prototyping processes are a relatively recent teaching, accurately set forth as layer manufacturing processes. The first commercial RP machine was released at the AUTOFACT show in Detroit (USA) in November 1987 by the company named 3D systems. The process begins with creating a 3D model using CAD software and it is identical for all built techniques. The model is then convert in to Standard Tri angulation Language (STL) format, this format shows the 3D surfaces as an fabrication of many planner triangles. At next stage STL file slice the 3D model in to layers. As we know the additive manufacturing is gradual process in which parts are manufactures through layers and each layers are joined and process continues until the final part formed. Post processing is usually required to break the surface finish of the product.RPs additive nature allows is to create parts with complicated internal features which is not possible by other means like grok areas and undercuts for that these parts sometimes supports are necessary. (palm, W. (1998, May). Rapid Prototyping primer. Retrieved November 4, 2010, from Learing factory Rapid prototyping hearthstone page http//www.mne.psu.edu)RP products often have low functionality and commonly used as a visual aids with in product development. However material selection decide the prototype testing for short term functionality parts. Most of the RP materials are polymer based, which is for special(a) part functionality. Although for little part functionality paper and starch based materials are used. RP modernised the product development with an ability to produce single and multiple somatogenic models, facilitating the reduction of product development cycle time ranging for different industries.1.3.1 Rapid prototyping technologiesThere is a huge number of experimental RP technologies either in development or used by small groups of individuals. RP techniques those are currently commercially available includingStereolithography (SLA) is the first RP technique developed by 3D systems in 1987. SLA builds single layer at a time by tracing beam of optical maser on the vat of liquid UV curable photo polymer resin. UV light strikes the surface of the polymer resin and solidify the single layer of resin, when one layer is cured the built platform is dropped down by single layer thickness (Schmitt, Q. L. (2005). Rapid protot yping in dentistry technology and application. Rapid prototyping in dentistry technology and application , 11-13,42,44). A resin filled sword sweeps everyplace the cross section and fill it with fresh material for further curing at the top of the previous layer, process continues until the model is produced. Material self resinous property bond each layer and form a complete 3D model, fabricated part is cleaned in dawanol resin, alcohol and then cured in a UV oven. (wikipedia. (2010). wikipedia free encyclopedia. Retrieved November 1, 2010, from wikipedia web site http//en.wikipedia.org/wiki/stereolithography)Selective optical maser sintering (SLS) uses powdered materials. This is one of the systems major advantages that a part could be built in any fusible powdered material. SLS technology was developed in Texas University, which was commercialized in 1993 by company named DTM. In 2001 the DTM were bought out by 3D systems. (http//www.jharper.demon.co.uk/rptc01.htm)This technol ogy works by selectively sintering fine powder materials directly using an infrared (IR) laser from CAD. Numbers of thermoplastic materials are processed in SLS like nylon (polyamide) for rapid tooling application, aluminium filled nylon, polystyrene for sacrificial frame in investment casting and gas filled nylon. Part produced through this process used as functional model as hale as visual prototypes because of substantially mechanical properties.However as compared to traditional tool marque the part had poor mechanical properties, so material required positioning processing to form dense models, thus it was very difficult to control the part accuracy because of introduced stresses in processing stage. With the combination of EOS GmbH and Electrolux a special alloy powder was developed, which did not develop shrinkage distortions. Moreover introduction of fibre laser technology allowed the introduction of Selective laser melting (SLM) since the fibre laser allowed the sinter ing of metals that were completely melted in to dense part with no need of post process infiltration.Numbers of other technologies have been commercialised since 1991 such as laminated object manufacturing (LOM), fused deposition modelling (FDM), 3 dimensional printing (3DP). Recent technological availability of RP is increased with material diversity, which increased the efficiency of creating physical prototype in in advance(p) product development.1.4 Definition of Rapid ManufacturingFirstly, it is essential to experience a definition of rapid manufacturing. The way that several parts are manufactured will change in the future. RM has been explained as the use of a CAD-based machine-controlled AM process to construct parts that are used directly as finished products or constituents (Hopkinson et al. 2006, p. 1)Since with the time change, the research on AM technologies and materials has advanced and the feasibility of fabrication of functional, low batch parts are increasingly in many industries. Many industries are examining the available technology and investigating the possibilities of externalize to increase the soaring functional component and to reduce product to market time. A key benefit of RM approach claimed that it proposes the opportunity of mass customization, however discount be cost effective for individual short run part, clearing conventional designing constraints of manufacturing processes. RM bigly minimised wastage of raw material as compared to subtractive process, so got popular in aerospace industry, where expensive metal alloys are extensively used. The bulls eye material such as si, ABS, nylon and aluminium has been the important part in the pass around of RM technologies.(http//www.hse.gov.uk/horizons/rapidmanufacturing.pdf)The introduction of RM is not as simple as it first appears, although research in RM technologies and application are attainmented by RP. The evolution is still in progress to link RM from research to actual manufacturing for that number of matters to be addressed that prevail need explanation and consensus before it can happen. RP produced prototype were not considered for product repeatability and quality measures. Since products of RM have proposed functionality, industrial certification and the requirements include material control, accuracy, speed, surface finish and part repeatability, so that RM is successfully applied in many industries including medical, automotive and aerospace to produce low quantity of small, richly value parts with complex geometries that is difficult through conventional methods.(http//www.rm-platform.com/index2.php?option=com_docmantask=doc_viewgid=129Itemid=5)In future, RM technology addition in industries can offer small complex design feature parts that ever imagined with great manufacturing facilities and the extension of approach. Development of advanced materials and equipment enable the fabrication of complex product by directly manipulati ng the matters on a molecular scale.1.5 Selective laser melting (SLM)1.5.1 SLM backgroundSelective laser melting machine was first introduced by Fockele and Schwarze (FS) of Germany in 1999 with the support of Fraunhofer institute of laser technology that was steel powder based SLM machine. Later in 2004 first SLM machine named Realizer 250 SLM was released commercially after FS coped up with MTT (MCP tooling technologies) and in 2005 high resolution machine named SLM Realizer 100 was released.Since the release of the MCP Realizer SLM, other manufacturer such as Concept laser and EOS released machine with different process named Laser curing and Direct metal laser sintering respectively. Concept laser (GmbH) first released M3 Liner and M1 Cusing in 2001, later they released another machine named M2 Cusing to produce oxidizable materials like titanium and aluminium alloys. EOS released the machine named EOSINT M 270 DMLS in 2003 and termed as the most common machine for direct metal fabrication. In 2008 MTT and 3D systems announced a distribution agreement for the rights to distribute SLM machines in Americas and Japan. In 2008-09 new version of SLM was released by MTT named SLM 250 and SLM 125.1.5.2 Basic principles of SLMSLM is a powder based additive manufacturing process that permits attaining 3D functional parts from a CAD data. SLM follows the same process route as SLS, where complete melting of powder occurs instead of sintering or fond(p) melting.Process begins with the deposition of thin layer of powder thickness ranging from 50m to 75m across a substrate platform. A high power fibre laser scans the powder surface, the generated heat melt the powder particles and form molten pool. Once the layer has been scanned, the platform drops down by single layer thickness in z axis and the fresh layer of powder is deposited and the process is repeated until the entire built is completed. Loose powders are secluded once the fully dense part is complete. SLM p arts must be completed in inert gas atmosphere such as argon to remove oxygen from the building chamber. Supports like thin teeth shaped are needed to secure hanging features due to shrinkage of material solidification. The substrate is removed from the build chamber once the process gets complete and supports are removed carefully.SLM termed as the most viable techniques for direct fabrication of complex feature part of metals. SLM can permit the design optimization and production of the complex functionalities beyond the capabilities of traditional techniques, which is possible because of accuracy, versatility and the laser beam spot size. The small laser spot size minimizes the area to be melt enabling the manufacturing the part of high resolution. However, to be positioned SLM in RM category as a general method to achieve greater recognition in companies, methods and development need to be changed to perform and prove itself as being reliable, repeatable and cost effective prod uction process.SLM besides known as freeform fabrication process and capable to build thin wall complex features models of high resolution and extends its capabilities than the conventional processes such as customised medical implant especially alveolar crown and bridge frame work, tooling inserts with conformal cooling channel and functional models.SLM concerns primarily subprogram around the application of high powered fibre laser to generate high temperature to completely melt the powder, surface roughness is the master(prenominal) concerns of SLM because of high heat enter causes material desiccation and generation of spatter that subjected by melting and re-solidifying. But SLM parts cover committed microstructure parts and material properties that make possible this technique for the application.Benefits of SLMParts produced in this process are nearly 100% dense and have same mechanical strength as the original materialAlmost no powder material is wasted, the escaped p owders which was not solidified can be reusedSLM offers minimum time to market, exact shape generation without an expansive moulds, process flexibility and great utilization of materialSLM powder bed technology permits cheap and fast powder metallurgy. The alloys to be tested can utilized straightly with in the prototyping apparatus and alloys can easily accustomed with the change of elemental ratio of powdersDrawbacks of SLMSLM is regarded as the high temperature gradient, which causes thermal stress build up and rapid solidification so brusk to grainy surface finished parts are producedThe inadequate availability of some materials in powder form restricts the range of material for processing. Process should be optimised for available material(Selective laser melting, 10 December http//raproto.com/?cat=31, accessed on 25/5/2011 and http//www.mtm.kuleuven.be/Onderzoek/a2p2/researchtopics/SLM, accessed on 26/5/2011)1.5.3 SLM materialsSLM technology worked with all mayhap relevant me tals for part production. Process starts with identifying the physical behaviour of material being used with microscopic level of process understanding. In order to develop technique, the main quality aspect of parts being produced includes surface roughness, high functional strength, accuracy, density, hardness, residual stresses have to be observed before applied for the industrial applications. SLM system always develops parts with variety of materials and new ranges in which material property is easily changed with the property requirement with changing the mixture ratio. The range of materials are used that improved the new work powders such as tool steel, stainless steel, titanium alloy, aluminium alloy, cobalt chrome and inconel.(http//www.mtt-group.com/data/pdf/extract/0413-MTT_2pp_SLM_A4_%20Flyer_v1.pdf)Materials are described below according to property, alloy and applications(http//www.xyzinnovation.com.au/assets/slm-brochure_290709.pdf)TitaniumMechanical properties High strength, low thermal expansion, high corrosion resistance, excellent machinability and bio compatibility and low weight.Alloys Pure titanium, Ti-6Al-7Nb and Ti-6Al-4VApplications Medical implants, jewellery and design, F1 motor sport and aerospaceCobalt chromeMechanical properties High strength, excellent corrosion resistance and bio compatibility and high toughnessAlloy CoCr ASTM F75Applications medical implant, dental and high temperatureStainless steel, tool steelMechanical properties High toughness, hardness and corrosion resistance and excellent machinabilityAlloys 316L stainless steel, H13 tool steel, 17-4PH, 50CrMo4, CrNiMo 13-4 and M333Applications medical implants, spindle and screws, plastic dig moulds and maritimeAluminiumMechanical properties Excellent alloying properties and processability and low densityAlloys Al-Si-10Mg, Al-Si-12Mg, Al-Si9-Cu3, Al-Si-7Mg and Al-Mg4Applications Aerospace, automotive, consumer goodsInconelMechanical properties Good mechanical strength , excellent corrosion resistance, outstanding welding ability and good creep rapture strength up to 700CAlloys Inconel 718 and Inconel 625Applications Aerospace, gas turbines, space shuttle and crafts, nuclear reactors and rocket motorsIntegration of SLM in production systemsProcess chain business office SLM process chain PartFinish(Machining)Part DesignProcessStrategyProcessControlProcessPreperationDesigned for optimized Part orientation built strategy online defect Interface forFunctionality (quality/ build time) -built parameters detention machining(light, weight, -support structure -under cuts etc -close loop controlenergy efficient etc )(www.materialscluster.lu/content/download//Wilhelm_Intermat2011.pdf, accessed on 30/5/2011)SLM machinesSLM50 RealizerWorlds first SLM desktop machine to produce quickly and extremely accurately manufacture functional dental parts based on CAD data. It is well appropriate for dental laboratories and similar environments for the production of brid ge and crown frame and brackets. This machine is capable to produce 100 parts/ months. SLM50 designed a component with height up to 40mm and diameter up to 60mm.(http//www.industrialnews.org/2011/03/worlds-first-slm-desktop-machine-dental.htmlixzz1NtOkViL9)SLM50 specificationsConstruction volume platform diameter 70 mm, max. construction height 40 mmThickness of layers 20-50 mLaser type Fibre laser 20 to 120 W spot supply 16A, 230VPower consumption 1.0 KWArgon consumption approx. 30 Liter/hDimensions W800 x D700 x H500 mmWeight approx. 80 kg software program ReaLizer Control SoftwareMaterials Cobalt Chrome, Stainless Steel 316 L,gold-, silver-, palladium-, titanium alloys(http//www.progold.com/GB/Files/Realizer.pdf)httphttps://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPSveLQBO9KYjnA291ARieNEU9_PhL7B944oi0mNXG6XqeZ2EMYAW1lwaJdL9TzbmURk46L-GWfW96vGNzG3DSphDT-f744ZD7Vk9Y1gUr7lK-WSxYEXGhLtlic62A59x2u6yM2W8vacVT/s1600/SLM-50-1024682.jpg(http//www.industrialnews.org/2011/03/worlds-first-slm-desktop-machine-dental.html)SLM100 RealizerMachines capability to design a component with 100mm high cylindrical constr uction area with 125mm diameter, because of the dropped laser spot size to 20m. The machine can produce parts with delicate features, high surface quality and maximum wall thickness. SLM100 is appropriate for dental laboratories or related environments.SLM100 specificationsConstruction volume Platform diam. 125 mm Max. overall constr. height 100 mmLayer thicknesses 20-100 mLaser type Fibre laser 20 to 200 WPower supply 16A, 400VPower in stupefy 1.5 kWArgon consumption app. 35 l/hDimensions W900 x D800 x H2400 mm, SLM100A additional display support armWeight 500 kgSoftware ReaLizer control softwareMaterials Tool steel H 13, titanium, titanium V4,aluminium, cobalt chrome, stainless steel 316 L,Inconel, Gold, ceramic materials under development(http//www.realizer.com/en/wp-content/themes/realizer/ReaLizer.pdf)(http//www.twi.co.uk/content/laser_slm.html)SLM125The SLM125 machine presented with a range of laser from 100-200W with 30mm laser spot size diameter. This machine is capable to b uilt pattern geometries of 200m. Surface finish is controlled by laser scan approach, however build speed and surface finish is majorly depends on material that to be processed such as tool steel take more time than the aluminium and titanium. For fully dense part the both parameters surface finish and build speed should range from 15-30m and 5-200cm3/hr respectively.(http//www.sme.org/cgi-bin/find-articles.pl?ME09ART20ME20090401SME)This machine has been designed for the simplicity to the users with in a industry with touch screen features, which cleans down the process. Robustness of the machine has given precedence to the adopters. The recoater blade used in this system is soft and carefully designed to reduce consumable cost by rotating same blade many times before replacement, and low filter element causes low gas consumption, results machine reliable and minimum in cost to users.SLM125 specificationsConstruction volume 125mm x 125mm x 125mm (x,y,z)Layer thicknesses 20 to 100mLa ser type Fibre laser 100-200 WPower supply 16A, 400VPower inputArgon consumptionmDimensionsWeightSoftware ReaLizer control softwareMaterials Tool steel H13, titanium , titanium V4, aluminium,cobalt chrome, stainless steel 316 L, Inconel(http//www.mtt-group.com/data/pdf/extract/0413-MTT_2pp_SLM_A4_%20Flyer_v1.pdf)MTT SLM25(http//develop3d.com/profiles/box-clever)SLM250This machine measures construction area of 250-250-250mm. The space in the processing area can be used to produce maximum number of parts with loading numerous parts at the top of each other. SLM250 is equipped with high power laser up to 400W with an automated filter machine to remove and recycle loose powders from the processing area. High part output makes it appropriate for industrial manufacturing process.SLM250 specificationsConstruction volume 250 x 250 mm , maximum construction height 220 mmLayer thicknesses 20-100 mLaser type Fibre laser 100, 200 or 400 WPower supply 16 A, 400 VPower input 2.5 kWArgon consumpti on app. 70 litres/hDimensions W1800 x D1000 x H2200 mm w/o sieving machineWeight 800 kgSoftware ReaLizer control softwareMaterials Tool steel H13, titanium , titanium V4, aluminium,cobalt chrome, stainless steel 316 L, Inconel(http//www.realizer.com/en/wp-content/themes/realizer/ReaLizer.pdf)http//www.renishaw.com/media/img/gen/8a0166f5acc64a4190c81957ffe11b05.jpg(http//www.renishaw.com/en/renishaw-acquires-mtt-investments-limited14897)D1 (http//doc.utwente.nl/52914/1/Wa1025.pdf)D2 (http//pic.sagepub.com/content/220/6/857.full.pdf)D3 (http//www.meditech.cf.ac.uk/pages/Individula%20Meetings/fifteenth%20Nov%202007/presentations/R%20Bibb%20-%20PDR%20-%20ARUP%20Nov%202007.pdf)SLM 125 machine runSLM 125 machine operated in the following mannerTurn on from the back- MTT 125 screen showed up- Tap on the screen- Login with the user name MTT2- Tap light (light readables)- Tap to open the door- hold reset and open the doorWiper reset Tap to wiper and rhytidoplasty on the screen- find wiper home- rap to substrate and set thickness to 0- press Esc- hold reset and open the door. Tap to wiper and elevator- find wiper home- Go to FWD POS- then unscrew the wiper arm from both endsTo draw material holder or wiper tension unscrew both the sappy placed at the ends with pressing at the top. Attach back both the wiper tension and wiper arm to their respective positions- shut the door in front placing the platform in the machine , first measure the base plate with vernier calliper then Tap to wiper and elevator- find wiper home- tap at substrate and set the thickness to 14.5- tap at table auto (it will built)- Tap at set datum- find table home. Go again- substrate set to 0- Go to top POS- Tap at Go to Centre to position wiper at the centreCUsersP10507465DesktopWiper_tension1.JPGLift wiper and place paper then tight it. Clockwise rotation of screw to loose and anticlockwise to tight it. Later paper is removed. Just ensure that you should put the same pressure during screwing. Af ter setting the wiper arm at the paper sheet thickness- close the door- tap to wiper and elevator- find wiper homeTo clean filter assembly Remove both caping placed at the top and bottom and do not forget to remove the rings- unbolt the holder- remove the filter (twist and draw)- clean the chamber- push filter to attach- bolt itCUsersP10507465DesktopFilter_Assy.JPGCUsersP10507465DesktopFilter_removal.JPGTap to wiper and elevator- find wiper home- set datum- Dose to 3- Go to FWD POS- open with guardianship reset button. close down the door- find wiper home- Esc- select- auto (safe change filter valve- yes)- auto operation starts- click ok- Isolate change filter- confirm. Operation or part building starts and it logged out automatically after finishing the operationLogin again with user name MTT2- tap to wiper and elevator- find wiper home- Go to up- Esc- open the doorCleaning Slowly remove the powder with the brush- later hover it to clean properly. Unscrew the base plate- Brush ag ain not to waste powder. Close the door- wiper elevator- find wiper home- Go to FWD POS- Esc- open the door holding reset buttonUnscrew the wiper plate and clean- the red strip on the wiper arm turns black at worked portion means damaged. Unscrew material holder- brush the machine to restore loose powder to the holes (for titanium alter is really important)Over flow cleaning Unscrew loose powder holder underneath the platform. Put screw at close position and turn around to unscrew it to recover loose powders- screw it and place it in desired place including rings and capingSet wiper back at the position to clean lense- unscrew it and clean it with proper handlingDental suprastructureThe manufacturer is also is involved in the dental industry, for which the company manufactures products such as implant-supported suprastructures. victimisation patient-specific geometry data, acquired through medical imaging or 3-D scanning, the personalised structure is designed in software and prin ted in titanium. As a concluding step, the dental technician finishes off the structure and completes the final prothesis.Through patented DentWise technology, geometry and surface retention related limitations set by traditionally moulded or milled suprastructures no longer apply.Through digital SLM technology, geometry and surface retention related limitations set by traditionally moulded or milled suprastructures no longer apply, Mercelis says. In addition, the implant connections are completed with high precision. Implant bars and bridges achieve a fit accuracy better than 20 m at the implant interface. They also can integrate complex surface textures and sealing edges. DentWise suprastructures are manufactured using ultra-strong titanium alloy (Ti6Al4V, grade V), which outperforms the commonly used titanium grade II in terms of mechanical propertie(http//www.emdt.co.uk/article/selective-laser-melting)