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Module 1: Additive Manufacturing Categories and Process Chain

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Additive Manufacturing Technologies and Categories

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Now, let us examine the positioning of additive manufacturing in the landscape ofmanufacturing. In the current IOT enabled industry 4.0 concept kind of dominated scenariowith that is prevalent in the manufacturing systems. We are talking about optimizing the
resources, improving the machine utilization, real time sharing of the information based ontremendous sensorization, ubiquitous computing and more importantly rapid elasticity.
If you just contrast the scenario with that of the early models of manufacturing, where thefocus was only limited to increase production, and reduce labour costs, it has been atremendous metamorphosis. The early models of additive manufacturing came into existenceway back in 1980 itself. In fact, the first ever patent to the concept of XYZ plotter could becredited to Kodama from a yoga municipal research institute from Japan.
Wherein he talked about producing a 3-dimensional plastic object directly from the digitaldefinitions. But initial set of additive manufacturing systems were not capable of producingthe parts out of engineering materials with necessary surface fidelity and dimensionalaccuracy that are commensurate with the expectations of serious engineering applications.So, most of the applications in the initial stages were confined to prototyping and designvisualization.
But in course of time, there were tremendous contributions from laser physics, polymerchemistry, control systems, software engineering, in-situ process monitoring, and with allthese contributions coming in, the systems became more versatile and the output wasavailable in multitudinous materials. Hence, the industrialization of additive manufacturingbecame a possibility.
So, today, we are not looking at usage of additive manufacturing technology only for the sakeof prototyping or for design visualization, we are looking at more powerful models throughwhich additive manufactured parts can fulfil the end user needs or functional requirements ofreal-world applications.(Refer Slide Time: 08:21)
Now, if you look at the important aspects of additive manufacturing, there is a distinct phasewhere we are looking at only digital information. In the initial phase of the process ofadditive manufacturing, we are working on digital models or CAD models and slicing thesemodels into series of layers mathematically using certain customized software solutions.Subsequent to that the slides data is converted into thin layers or to plastics and metalssequentially.
So, that digital definition is translated into physical part. The point which is to be appreciatedis, there is a phase which is working only on the digital data and there is a phase which islargely confined to physical models. It is interesting to know that initially, when thistechnology came into existence, it was more known as rapid prototyping technology. Incourse of time, several phrases were used to refer to this technology including leadmanufacturing, solid freeform fabrication.
The terminology called 3D printing came into existence, because of the research group ofMIT that were talking about producing the additive manufactured parts using jetting kind of aprinciple or inkjet kind of principle out of plastic materials.(Refer Slide Time: 10:09)
But currently, the terminologies like 3D printing and additive manufacturing are used fairlyin interchangeable manner. So, if you are looking at the conventional manufacturing what isvery apparent is, it is sequential from the stage of drawing to the stage of the realization of apart. There are certain steps sequentially you need to follow including development of thetooling’s, fixtures, machining, which predominantly involves removal of the material.
Stage inspection depending upon the complexity of the geometry and final realization of thepart. In contrast to that, additive manufacturing or 3D printing tend to be one step solutionsthat is direct translation of the digital data into physical part in a solid free form approach.(Refer Slide Time: 11:08)
So, what is the formal definition of the additive manufacturing. As for the standard ASTMF2792 released in 2009, additive manufacturing can be described as a process of joining
materials to make objects directly from the 3D CAD model data usually layer upon layer asopposed to the subtractive methodologies. The standard has been replaced by the ISO ASTMstandard 52900 released in 2015 but the definition minds the same.
As I mentioned the terminology 3D printing was coined by the group at MIT Emanuel Sachsin 1993. The Fraunhofer society is credited with the development of the selective lasermelting process through which you can work on range of metallic materials.(Refer Slide Time: 12:04)
I f you look at the materials that can be processed using additive manufacturing, you can see3 important characteristics, 3 important categories, right in the center we got metallicmaterials, that can be processed through powder bed fusion or binder jetting or direct energydeposition. You have got a set of processes which are connected with thermoplastics andthermoset plastics, thermoplastic plastics and other group the others could be connected withprocessing of sand, glass, composites, fiber optics, even organic tissues.
I have shown 3 examples in this case right on the top is a flame tube, which is made fromhigh temperature nickel super alloy, made through powder bed fusion. In the bottom you seea transparent or bearing housing. In the centre, you see a compositor piping or with the thinwall realized through 3D printing out of peak like materials.(Refer Slide Time: 13:16)
So, if you look at the possible options in processing of polymeric materials using additivemanufacturing, you can see the important technology that has been available in thecommercial form right from early 90s is the VAT polymerization technology. Then, you gotextrusion technology, where in filaments are extruded into the physical parts. You have got amaterial jetting technology wherein the plastic materials are jetted out.
The fourth option, a versatile option is the powder bed fusion, it is also now more popularlyknown as selective laser sintering which involves the usage of high energy sources forrealization of the polymer parts.(Refer Slide Time: 14:17)
Now, let us look at the options connected with metal additive manufacturing. Predominantlyyou see two varieties in the commercially mature a mature form. The first one is the powder
bed fusion, wherein you spread thin layers of powder on the bill platforms, make use of highenergy laser sources could be lasers, could be electron beams, for melting of these particles,which resolidify as the beam passes along.
On the other side we have got direct energy deposition process where in to the stream of thehigh energy source, you are injecting fine metallic particles. So, these two are the distinctprocesses, which are used in the world of metal additive manufacturing.(Refer Slide Time: 15:15)
But if you look at the categorization of the key metal AM technologies with reference to theNASA's publication of 2019, you can see three categories corresponding to powder bedfusion, direct energy depletion and solid state. Important thing to notice the feedstock in caseof direct energy deposition could be in the form of powder or could be in form of wirewhereas, in case of solid state, it may also involve a foil.
There are a lot of options interesting options which are continuously emerging. But, oneimportant option especially with reference to the repair and refurbishment of worn out parts isdirect energy deposition technique. The cold spray technique, wherein fine powder particlesare accelerated in a high velocity compressed gas stream is one of the emerging options.
These particles upon the impact with the substrate they deform and bond together creating alayer and eventually creating a pre-defined geometry. So, these are some of the options whichare being used in the industrial contexts.(Refer Slide Time: 16:39)
In this slide, you will see an indicative representation of the parts that have been realized atthe plant of Wipro 3D using powder bed fusion technology. You can see here parts made outof titanium alloys, aluminium alloys, nickel alloys and steels. What is interesting to see is theobject which is shown in the left portion of the slide is an anti icing assembly for aero gasturbine engine.
Many of the parts which are got intricate geometrical definitions including the bullet nose andthe airfoil sections have been realized using additive manufacturing technology of powderbed fusion whereas, the sheet metal components large in size have been realized using theconventional manufacturing. So, this is a manifestation of a synergistic combination ofconventional manufacturing with additive manufacturing. This approach is becoming moreand more popular as hybrid engineering approach.(Refer Slide Time: 17:51)
So, if you look at formal categorization of additive manufacturing technologies, as perASTM, ISO standard 52900, you see seven distinct categories of the technologies includingthe vat polymerization, material extrusion, powder bed fusion, material jetting, binder jetting,directed energy deposition, and sheet lamination. Each of the technologies comes with itsown set of possibilities, merits and some of the associated challenges.
But it is very important to know that you need to pick up the technology, you need to pick upthe material depending upon the application that you would like to show.(Refer Slide Time: 18:37)
One of the recent examples which I would like to project is the one connected withdevelopment of the face shield very important product during the pandemic situation. In thiscase, the supply chains were severely disrupted and what you see in here is a custom
developed face shield with the limited access to the supply chains using multi jet fusiontechnology for production of face, eye and nose.
Despite the fact that there are no access to the injection molding resources, in these disruptedtimes, the MJF technology was used to produce close to 1500 pieces per day and whathappens in this technology is a fusing agent is jetted selectively where particles need to beprocessed, plastic particles need to be processed and the detailing agent is jetted across thecontour or the periphery to get top notch geometrical definition.
So, fundamentally can process the polyamides and also thermoplastic polyurethane kind ofmaterials in steps of 80-micron layers and the small series production of this kind is greatlyfacilitated using the additive manufacturing technology of multi jet fusion.(Refer Slide Time: 20:08)
The other example I would like to give connected with an industrial context is application ofa stereolithography part, a stereolithography is part of the vat polymerization context. Youcan see on the left-side a full-scale bearing housing on the material is a photocurable resinand it happens to be translucent. So, you can even see the fluid motions happening within thispart and this full-scale bearing housing has been fitted in an attitude test facility.
The moment of the fluids within this full-scale model of the bearing housing over capturedfor flows visualization studies. So, this represents one example, wherein a part made out ofadditive manufacturing was directly used as a test article.(Refer Slide Time: 21:03)
The next application is connected with fused deposition modeling, one of the ubiquitousmodels of additive manufacturing. In this case, the parts can be made out of thermoplasticmaterials like polycarbonates, PLA, ABS, glass filled nylon. What you see in this case is amicro sized transmission gear wheel assembly realize directly using fused depositionmodeling and fitted into an ornithopter for converting the rotary motion into the flappingmotion of the wings.
This ornithopter is ready for fuel application, do demonstrate what kind of thrust and lift canbe generated by the configuration under examination. So, this is one more example of directutilization of additive manufactured plastic part in real world context, without dependence onthe conventional tooling and conventional manufacturing processes.(Refer Slide Time: 22:14)
This is an example corresponding to the customization of the implants. You can see here theX-ray data corresponding to the patient who has lost a significant portion of the pelvic girdleand this is a 3D visualization and what you see on the right side is the translation of thereconstructed CT data into a full-scale thermoplastic assembly made through the fuseddeposition modeling system out of ABS material.
This is used both for communication purposes as well as surgical planning. So, this is onemore example of using the additive manufactured part or model for planning a complexsurgical procedure.(Refer Slide Time: 23:09)
This is an interesting example corresponding to the development of spare parts for legacysystems. In this case, the stakeholder had only access to the use part. So, the geometrycorresponding to the part had to be captured using 3D scanning and using that as a reference,the part was made out of powder bed fusion using speciality steel. This is one excellentexample of developing reliance in case of spare parts for strategic sectors.(Refer Slide Time: 23:51)
So, there were resize limitations in the initial stages, because of the fact that the concept ofdesign for additive manufacturing was still evolving. But if you look at the current set ofapplications published by NASA in association with the southwest research institute, thereseems to be no apparent limitations with reference to the size of the part that can be tackledusing additive manufacturing.
In this case of RS-25 engine project of NASA, the parts as big as 2.5 meter in diameter withthe wall thickness of 6 mm have been realized using additive manufacturing.(Refer Slide Time: 24:38)
So, this is a very busy slide or wherein you can see the parts corresponding to the gas turbineengines, communication systems, small turbofan engines, instrumentation housings, made outof diversified material, using additive manufacturing. You can even see one orthomode
transducer, a waveguide competent made out of a ALSI 10 mg, made through powder bedfusion using one of the prominent technologies in additive manufacturing. The commondenominator to all these applications is the geometries are relatively more complex.(Refer Slide Time: 25:24)
In these cases, if you were to rely on the conventional manufacturing, the waste that isassociated with conversion of your design into the part could be significantly high. Becauseyou start with a block of material, you remove unwanted material with the help of geometryspecific tools and processes. In the bargain, you are continuously generating the waste. Incontrast to the situation, if you were to employ additive manufacturing, as the process fortranslating the designs into the part, especially in case of complex designs, the waste could besignificantly less because you are only adding the material at the location of necessity.
Hence, in the context of aeronautical systems a phrase is called buy-to-fly ratio has becomeextremely relevant. The amount of material that; you are buying as compared to the amountof material which is finally used in the system that is flying.(Refer Slide Time: 26:38)
So, in case of conventional manufacturing, the buy-to-fly ratios, whether you are talkingabout milling, or casting, or sheet metal and machining, it could range anywhere between 8 isto 1 to 4 is to 1 ah depending upon the geometry of the part. But if you apply the principles ofdesign for additive manufacturing, and if we use additive manufacturing as an alternative tothe conventional manufacturing, it has been seen in some cases, the buy-to-fly ratio couldbecome as favourable as very close to 1 is to 1 and coterminous to this concept is alsosignificant reduction in the weight, which actually adds to the overall impact on the system.(Refer Slide Time: 27:25)
One very important thing that has been associated with the application of powder bed fusionin case of aeronautical systems is the concept of monolithising or converting multiple partsinto single part. It is also known as part consolidation, whether you are talking about a flametube or whether you are talking about a complex shape gyro housing.
(Refer Slide Time: 27:55)
What has been seen in these cases is significant weight reduction opportunity throughconsolidation and in the bargain the functional requirements may also get additionallyaugmented. So, here is a case study corresponding to the GSAT-19 a communication satelliteof ISRO launched into the orbit in June 2017 with a mission life of 10 years.(Refer Slide Time: 28:24)
The part that is shown here is the Northwest feed cluster made out of aluminium alloy calledALSA 10 mg using powder bed fusion at Wipro 3D in close association with SACAhmadabad. So, in this specific case 17 different parts of the feed cluster were combined intoa single part naturally, it resulted in a weight reduction, significant reduction in the assemblyeffort and hence the compression of the overall development cycle.
More importantly, because of the absence of the welded joints, the RF quality of the additivemanufactured part turned out to be quite superior to the conventional part.(Refer Slide Time: 29:14)
Because of these examples and possibilities and we have seen the global leaders like GEgiving a new shape to the manufacturing cycle in case of fuel nozzle an important part of theleap engine. Wherein this specific part made out of cobalt chromium alloy has undergone atremendous change as far as the process is concerned because of the infusion of powder bedfusion process into the development cycles.
As of 2018 GE has reported that more than 30,000 parts the nozzle tapes have been madeusing additive manufacturing using more than 40 plus metal 3D printers in 300,000 squarefeet facility and each of the engines the leap engines contained 19 of this 3D printed fuelnozzles and till now whatever is the quantum that has been reported to be produced, onlyaccounts for the requirements of about 1600 engines.
So, looking at the order book of GE and SAFRAN, you can understand the quantum leap orquantum improvement in the status of the industrialization of additive manufacturing in thecontext of aerospace sector. The other one, which is to be noted is the customization of theimplants using electron beam melting, whether we are talking about tissue grafts or cancertreatment, knee implants, or the hearing aids, we are seeing rapid advances in the proceduresusing 3D printing.
The processes allow one of manufacturing or mass specialisation and the healthcare productcompanies are quickly reconfiguring their supply chains. So that, the distributors and thehealth care providers, they are getting seamlessly connected and are able to meet therequirements of mass personalization or mass customization using 3D printing hubs. We haveseen in certain cases, that some of the medical device manufacturers are able to produce theseparts and deliver at the point of need in about 48 to 72 hours of time from the date of thereceipt of the CT data corresponding to the patient in need.
One more significant observation from the energy sector is the manufacturing of the pumpsand impellers out of corrosion the system steels and rather than depending on the traditionalinventory maintenance systems, they are producing the parts just in time and delivering at thepoint of care or point of need.(Refer Slide Time: 32:26)
So, the current uses of metal additive manufacturing in industrial context has become aninterplay of design, material science, laser physics, simulation technologies, post processingcontrol systems and software engineering. You are also seeing that there is a continuous shiftin the application landscape from the prototyping to batch production, so, as to meet thecomplex needs of the end users.(Refer Slide Time: 33:05)
Reflecting this kind of an improvement in the usage pattern of additive manufacturing,several publications have referred to the 3D printing as the third industrial revolution andduring the 2010 to 2015 kind of a timeframe many impactful publications brought out howthis technology is enabling the next industrial revolution.(Refer Slide Time: 33:42)
One of the important references in this case is the report of McKinsey global institute in2013, where in the 3D printing was placed alongside of other disruptive technologies likecloud technology, internet of things, the renewable energy, advanced materials and energystorage solutions as one important technology that can bring in disruption into the way thefuture businesses are run.(Refer Slide Time: 34:14)
So, this is a very famous Gartner hype curve additive manufacturing is no exception to thiskind of a trend. When this technology was introduced about 25 years ago, there wastremendous amount of enthusiasm among the stakeholders from multiple sectors. There was apeaking of expectations. Soon they realized what are the limitations that are synonymouswith additive manufacturing, especially with reference to the strength, surface quality, as wellas dimensional accuracy.
So, there was a phase which is synonymous with disillusionment. We are in a phase wherethe users are able to understand the possibilities in much better way. They are also able tospot the specific instances where induction of or infusion of this technology can produce theparts with the necessary technical as well as business impact.(Refer Slide Time: 35:20)
So, what are those instances when you are talking about aeronautics, there are many gasturbine manufacturers who are able to produce the parts connected with the turbinecombustor, exhaust and compressor modules with a lot of discernible impact on the timecompression using powder bed fusion technology. They are also able to make use of directedenergy deposition technology for repair and refurbishment of worn out parts.
We are seen in automotive sector especially in case of electrical vehicles and motorsports, themetal additive manufacturing and plastic additive manufacturing technologies are repeatedlyused for producing even the one of parts and maintaining the competitive advantagecompared to the peers. As I explained in case of medical industry, the surgical implantscustomized solutions for orthopaedic applications, for maxillofacial and craniofacialapplications are becoming more and more prevalent.
In case of space systems, development of monolithic rocket engines, and development ofsmall satellites are being pursued by research groups across the world using additivemanufacturing as an enabler. We have also seen in case of white goods sector, customizedgifting solutions, and the businesses connected with the customized gifting have evolved byintegrating 3D printing into the supply chain.
Similar examples can be cited from the world of electronics, the world of oil and gas. Oneimportant thing which can be seen in case of academic context is development of fab labs andmaker spaces by introducing additive manufacturing as one important constituent technology.(Refer Slide Time: 37:26)
So, with all these applications emerging, we have seen the overall business volume ofadditive manufacturing has crossed the levels of 11 billion US dollars, approximately 35 to38% of this business volume is contributed due to metal additive manufacturing and theremaining is because of the plastic additive manufacturing.(Refer Slide Time: 37:57)
It is also important to understand that not in all instances additive manufactured parts aredirectly used. As shown in this case, the part that you see on the left side of the slide is aquick cast pattern. It is a quasi hollow pattern made out of photopolymer resin usingstereolithography, and this can be used as a substitute for conventional patterns in case ofinvestment casting cycle.
On right side, you see an intricate statue of Sri Ganesha made using wax through the processof material jetting technology. This is once again a pattern an intricate pattern that has beenrealized using an additive manufacturing technology. So, there are direct uses of additivemanufacturing technology in the engineering context and there is a small but noticeableportion of indirect uses for patterns as well as for the bridge tooling.(Refer Slide Time: 39:08)
So, if you look at the overall product development cycle, and try to place these technologiesfor enabling the various phases of product development, you can see here the processes likematerial jetting, vat polymerization, extrusion and selective laser sintering that can handle thepolymeric materials. They become significant very relevant during the conceptualizationstage, wherein you are looking at several design iterations to be completed in the limited timeand arriving at the optimal solution as soon as possible.
If you are looking at the aftermarket or repair and refund point of use parts, you will see adistinct use case for directed energy deposition technology and in between, there is a spacefor technologies like powder bed fusion and binder jetting, wherein you are talking aboutmeeting the end user requirements using various metallic materials, and in these cases, we arenot looking at only 1 or 2 parts, we may be looking at series production or small volumeproduction.
There are many case studies where in the enablement of this kind of a need has beenattributed to the uses of powder bed fusion by the engineering groups.(Refer Slide Time: 40:48)
So, if you look at the technology options, you and try to position them with reference to twoimportant vectors. One is called industrialization and the other one is technology maturity;you can see that the technology of laser powder bed fusion is right on the top. So, it issynonymous with widespread industrial users. Just below that you can see powder laserdeposition technique.
Below that you can see plasma arc technique and other technologies are also catching that.So, in my coverage of the topic I will give plenty of examples corresponding to the usage oflaser powder bed fusion that signify the matured applications of the technology in theindustrial context.(Refer Slide Time: 41:41)
Just to sum up in this first session we understood the important characteristics of additivemanufacturing processes and we also got sensitized to the differentiators those are theconventional manufacturer. We also discussed the various categories of additivemanufacturing technologies based on the operation principles and the compatibility withdifferent materials and the business cases and application potentials that are synonymous withthese technologies have also been discussed in brief. So, we will further explore the typicalapplications of these technologies in the various face set of product development in theensuring session. Thank you.