crazymech.weebly.com€¦ · Web viewRAGHU ENGINEERING COLLEGE. Permanently Affiliated to JNTUK, Approved by AICTE. Accredited by NBA. Ranked AAA by Careers 360. Ranked A Grade by

RAGHU ENGINEERING COLLEGEPermanently Affiliated to JNTUK, Approved by AICTE

Accredited by NBARanked AAA by Careers 360

Ranked A Grade by AP State Knowledge MissionRanked 63rd among Top 100 Private Engineering Colleges in India

by Higher Education Review Magazine.Ranked 92nd among top private Engineering colleges in India

by the Week MagazineRanked 14th among 33 promising Engineering Colleges in India by GHRD

www.raghuenggcollege.com

DEPARTMENT OF MECHANICAL ENGINEERINGIV B.Tech 1st Semester

Additive Manufacturing –III unit

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UNIT – IIITopics to be covered:Powder – basedrapid prototyping systems: Selective laser sintering (SLS): models and specifications, process, working principle,applications, advantages and disadvantages, case studies. Three dimensionalprinting (3DP): models and specifications, process, working principle,applications, advantages and disadvantages, case studies.

Day – 121. Explain the Selective Laser Sintering process.

Ans:- It is a powder based RP process that was developed by Dr. Carl Deckard

and Dr. Joe Beaman.- Initially the SLS machines were being marketed by DTM Corporation till

2001, when it was acquired 3D systems. So, now SLS machines are manufactured and marketed by 3D Systems.

- It is the only process that can make variety of engineering thermoplastic, metallic, ceramic and composites all from one system.

Process:In this process the final 3D parts are made byfusing the powder material. The complete process can be explained in three steps:

i. Pre-processing- First of all, the 3D model of the part to be developed is prepared and

like other RP process the prepared 3D model is converted to STL file format.

- The STL file is then checked and if any flaws are found it is repaired by software installed in the machine.

- After the flaws are rectified the 3D model is then sliced by the SLS software.

ii. Building- A thin layer of heat fusible powder is spread on the platform of the part

building chamber by the roller.- A CO2 laser then scans the powder layer as per the slice data with the

help of an optical scanning system. - The laser raises the temperature of the powder of the scanned area and

slightly melts it. This melted powder fuse together to form a solid mass. - The power of the laser is so adjusted that the powder where the laser

scans only melt and the rest of the area remains as it is.

Raghu Engineering College Dept.ofMechEngg. Additive Manufacturing Unit-III

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- After one layer is complete, the fabrication bed moves down by one layer and the powder supply bed moves up.

Figure 1An SLS Process

- The next layer of powder is then spread on the platform and the laser scans the next layer and the process is repeated till the part is complete.

iii. Post-processing- After the part is built completely, then it is removed from the build

chamber.- The loose powder surrounding the part simply falls away and it is reused

by mixing it with fresh powder. - Some secondary operations like sanding, lacqueringand painting are

done depending upon the application of the prototype built.2. Discuss about different SLS models currently available and write down

their specifications.Ans:3D system has introduced several generations of SLS system. Because of continuous research and development upgraded versions of the existing Raghu Engineering College Dept.ofMechEngg. Additive Manufacturing Unit-III

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models are being launched in regular interval. The current generation of SLS system includes SinterstationHiQ series SLS system andSinterstation Pro SLS system.

1. SinterstationHiQ series SLS systemi. The main features of this system are:- Ability to accurately monitor build temperature throughout the build

volume- Automatically calibrating on a layer – by – layer basis- Good part quality- Highly consistent mechanical properties throughout the part geometry

ii. This HiQ series includes two models- Standard HiQ model – uses a 30W CO2 laser with a Beam Delivery

System (BDS)- HiQ + HS model – uses 50W CO2 laser with high speed Celerity BDS thus

explaining high speed (HS) capability.

2. Sinterstation Pro SLS systemi. The main features of this system are:- Simple – to – use - Integrated with smart accessory package- Removable build chamber- Finished part retrieval station- Automated material recycling module- Provides clean, efficient, cost effective and automated round – the –

clock operating environment.

ii. This Pro SLS system includes two models- Sinterstation Pro230 - High capacity, Heavy duty rapid manufacturing

system, Can accommodate build volume upto 230L- Sinterstation Pro140 - Can accommodate build volume up to 140 L

Table 1Summary of specifications of 3D system’ SLS system

ModelsSinterstationHiQ series

SLS system Sinterstation Pro SLS system

HiQsyste HiQ + HS Pro 140 Pro 230


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m systemLaser type CO2 CO2 CO2 CO2

Laser Power (W) 30 50 70 70Maximum scan speed (m/s)5 5 10 10 10

Build Volume (L) 57 140 230CAD interface STL

Power Supply

230 VAC, 12.5 kVA, 50/60 Hz, 3-phase or 380 VAC, 12.5 kVA, 50/60 Hz, 3-phase

208 VAC, 638 A, 3-phase

3. What are the main components of a SLS system?Ans:3D system has introduced several generations of SLS system. The components of an advanced and completely automated SLS system i.eSinterstation Pro SLS system is given below:

- Hardware: 1. Sinterstation2. Rapid Change Module (RCM) – It is the build module mounted on

wheels for quick and easy transfer between Sinterstation, OTS and BOS

3. Offline Thermal station (OTS) – It preheats the RCM before it is loaded into the system and controls the RCM cool down after building.

4. Break – Out station (BOS) – The build parts are extracted from the powder cake here. The non-sintered powder automatically goes to integrated recycling station.

5. Integrated recycling station (IRS) – This station blends the recycled powder and fresh powder. The mixed powder is automatically sent to the SLS system for reuse.

6. Intelligent powder Cartridge (IPC) – It captures the material information when connected to IRS and this data is directly transferred to the SLS system.

7. Nitrogen generator – it continuously supplies nitrogen to the SLS system to keep the fabrication inert and prevent oxidation.

- Software:


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1. Build setup and Sinter (compulsory) 2. Sinterscan (optional)3. RealMonitor (optional)

Homework:1. Watch SLS process video.

Web Links: https://www.youtube.com/watch?v=9E5MfBAV_tAhttps://www.youtube.com/watch?v=gbtu3wBJ-pY

2. Explain the basic SLS process.Day – 13

1. What are the different types of material used in SLS system?Ans:

The material used in SLS can be broadly classified into three categories: 1. DuraForm materials2. LaserForm materials3. CastForm materialsDuraForm materials:The DuraForm group consists of five types:

i. DuraForm GF plastic- These are glass-filled polyamide (nylon) materials used for tough real

world physical testing and functional applications.- The features of these materials are excellent mechanical stiffness,

elevated temperature resistance, dimensional stability, easy-to-process and good surface finish.

- Applications of the material includes housings and enclosures, consumer sporting goods, functional prototypes, parts requiring stiffness and thermally stressed parts.

ii. DuraForm PA plastic- These are durable polyamide (nylon) materials used for general physical

testing and functional applications.- The features of these materials are excellent surface resolution, good

chemical resistance, complaint with USP class VI testing, easy – to –process and low moisture absorption.

- Applications of the material includes motor sports, aerospace, impellers and connectors, vehicle dashboard, snap-fit designs, consumer sporting goods, medical applications requiring USP class VI compliance.

iii. DuraForm EX plastic:


https://www.youtube.com/watch?v=gbtu3wBJ-pY

https://www.youtube.com/watch?v=9E5MfBAV_tA

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- These are impact-resistant plastic offering the toughness of injection molded thermoplastics and are suitable for rapid manufacturing.

- The features of these materials are toughness and impact resistance.- Applications of the material includes complex thin walled duct work,

motorsports, aerospace, unmanned air vehicles (UAVs), snap-fit designs, hinges, vehicle dashboards and bumpers.

iv. DuraForm Flex plastic:- This is a thermoplastic elastomer material with rubber like flexibility and

functionality.- The features of these materials are flexible, durable with good tear

resistance, good surface finish and feature details.- Applications of the material includeathletic footwear, gaskets, hoses and

seals, rubber parts.v. DuraForm AF plastic:- These are polyamide (nylon) materials with metallic appearance for real

world physical testing and functional use.- The features of these materials are as follows: metallic appearance with

good surface finish, excellent mechanical stiffness, easy-to-process, dimensional stability.

- Applications of the material include housings and enclosures, consumer products, thermally stressed parts and plastic parts requiring metallic appearance.

LaserForm materials:The LaserForm group consists of three types of materials as given below:i. LaserForm A6 metal- These are used to create complex metal parts mainly for rapid tooling

and rapid manufacturing.- Features of the material includes: good surface finish, compatibility with

machining, EDM processing and polishing, high surface hardness, excellent thermal conductivity and good green part strength.

- Applications include complex tooling inserts for injection molding, die casting, smaller and complex geometry metal parts, conformal cooling and heating channels.

ii. LaserForm ST – 200 material- This is special stainless steel composite developed to produce durable,

fully dense metal parts. - Features of the material are durable and functional.


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- Applications include direct metal parts fabrication, tooling inserts for injection molding, die casting, complex geometry metal parts.

iii. LaserForm ST – 100 material- This is powdered stainless steel. - Features of the material are part durability, suitable for metal parts and

mold inserts directly from CAD file without any casting or machining.- Applications include metal mold inserts, bridge tooling, short run of

metal parts and prototypes and complex geometry and features.CastFormmaterials:

- CastForm material is used to directly produce complex investment casting patterns without any tooling.

- Features of these materials are low residual ash content, short burn – out cycle, easy – to – process.

- Applications include creating complex investment casting patterns, near net – shaped components, expendable patterns etc.

Home work:1. Write down about the SLS materials and their applications.

Day – 14

1. What are the main principles involved in SLS?Ans:The basic principlesinvolved in any SLS process are:

i. Sintering- The powdered raw material is converted to final 3D object by a process

called sintering. Sintering is a process of compacting and forming a solid mass of material by heat without melting the raw material to the point of liquefaction.

- In this process when a CO2 laser beam hit a layer of powdered material, it increases the temperature of the powder temperature to glass transition temperature.

- Glass transition temperature is the temperature at which the material begins to softenfrom a solid state to a jelly-like condition. This often occurs just prior to themelting temperature.


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Figure 2 A Sintering Process

- As a result, the particles begin to soften and deform owing totheir weight and cause the surfaces in contact with other particles orsolid to deform and fuse together at these contact surfaces.

- After cooling, the powder particles are connected in a matrix that has approximately the density of the particle material.

ii. Layer-by-layer building- The building of the part is done layer by layer. After one layer is formed,

the next layer of fresh powder is spread by the roller mechanism directly on the top of already built layer.

- The CO2 laser then scans this fresh layer as per the data received from the software and the process continues till the part is completely built.

iii. Support structure- This process no additional support structure is required as the un-

sintered powder in each layer provides the required support to the next layer.

Day – 151. What are the process variables of SLS process that affect the final 3D

object?

Ans:

i. Properties of the powdermaterial (Viscosity, Stiffness, Thermal conductivity, binding characteristic)

ii. Accuracy of CO2 Laserbeam (Power)iii. Speed and resolution of optical scanning systemiv. Exposure parametersv. Accuracy of X-Y positioning tablevi. Accuracy of the elevation system(Z – height control)


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2. What are the strengths and weaknesses of SLS process?

Ans:The major strengths of SLS are:

i. Good part stability – Parts made have very good stability and hence can be directly used for functional applications.

ii. Wide range of processing materials – Awide range of materialsincluding nylon, polycarbonates, metals and ceramics are available,thus providing flexibility and a wide scope of functionalapplications.

iii. No part supports required – Thesystem does not require any additional support element as the loose powder in each layer provides the necessary support. This saves the time required forsupport structure building and removal.

iv. Little post-processing required –The finishing of the part isgood enough and that is why only minimal post-processing such asparticle blasting and sanding is done.

v. No post-curing required – The completed laser sintered part isgenerally solid enough and does not require further curing.

vi. Advanced software support – The advanced version of the software provides some advanced features like streamlined part scaling, advanced nonlinear parts scaling, in-progress part changes, build reportutilities.

Limitations:The main disadvantages of using SLS are as follows:

i. Large physical size of the unit – Thesystem requires a relativelylarge space to house it. Apart from this, additional storage space isrequired to house the inert gas tanks.

ii. High power consumption – Thesystem requires high powerconsumption due to the high wattage of the laser required for the sintering operation.

iii. Poor surface finish – Theproduced parts tend to have poorersurface finish due to the relatively large particle sizes of thepowders used.

3. What are the applications of SLS process?Ans:

i. Concept models – Physicalrepresentations of designs used to reviewdesign ideas, form and style.


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ii. Functional models and working prototypes – Partsthat canwithstand limited functional testing are prepared by the SLS process. Also SLS components are prepared to perform fit analysis of components for assembly.

iii. Polycarbonate (RapidCasting) patterns – Patternsproduced usingpolycarbonate, and then cast in the metal of choice through the standardinvestment casting process. These are built faster than wax patternsand are ideally suited for designs with thin walls and fine features.These patterns are also durable and heat resistant.

iv. Metal tools (RapidTool) – Directrapid prototype of tools required for moldsfor small or short production runs can be produced using SLS process.

Homework:1. Compare SLS and LOM process with suitable reasons. (8 Marks, Supply

Exam, Nov-16)2. Explain an SLS process in detail.

Day – 16

1. Explain about a few case studies on Selective laser Sintering process.

TESTSA Architecture/ Design – for Carbon Tower Prototypes

- In the “Extreme Textiles: Designing for High Performance” exhibition the design team of TESTA Architecture/ Design utilized SLS systems to build the prototype of Carbon Tower Prototype.

- The Carbon Tower prototypes demonstrates a new construction system for an all-carbon and glass fiber high-rise office building that is woven, knitted and braided as shown in the figure 3.

- This 40 story building engineered with ARUP software, is several times lighter and stronger than conventional steel and concrete structures.

- Given the intricate nature of tower design it was not possible to construct architectural models with traditional modeling materials and techniques.

- Using 3D systems’ SLS technology, the very large model measuring 60 inch by 14 inch diameter was fabricated in only five interlocking pieces from digital files prepared by TESTA.

- It proves that using SLS any complex and intricate geometry can be fabricated rapidly.


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Figure 3 Carbon Tower Prototype

The Crossblade outside Mirror

- General contractors Bertrandt developed the smart Crossblade for smart GmbH in just six months and built an exclusive series of 2000 with Binz, their production partners.

- The smart Crossblade was designed based on the concept of a smart convertible platform, which resulted in a final car design that had no roof, no convertible top, no screens and no doors.

- The new concept raised a number of issues, one of which is the mirror system. The Designers decided to develop a new mirror system to match this new concept.

- The SLS system and DuraForm PA material were used in building the model for mounting upper and lower shells (holding the rear-view mirror) and attaching them to door pillars. This helped in shortening the lead time required for injection molding tools.

- For functional testing, a laser sintered part was built and positioned on the test rig. After minor modification, the prototype passed the tests and the actual molded parts were fabricated.

Important questions in SLS Process:1. Explain a SLS process and parameters affecting SLS parts.2. Write down about the different types of SLS machine available in the

current generation.3. Write down the components of an advanced SLS machine.


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4. Write down various types of material used in SLS process.5. Explain the key principles of the SLS process.6. List out the advantages and disadvantages of a SLS process.7. Write down the difference between SLS and SLA process.8. Write down the differences between SLS and LOM process.9. Explain important applications of a SLS process.10. Write down a case study on SLS process.

Day – 17

1. Explain the Three Dimensional Printing(3DP) process.Ans: - It is a powder based RP process that was originally developed at

Massachusetts Institute of Technology (MIT) in 1993.- It was the patented by Z – Corporation in 1994. - The first 3D printer commercialized by Z – Corporation was Z 402 system in

1997. - In 2000 first color 3D printer was launched and in 2005 1st HD 3D printer

was launched by the company. Process:

Figure 4 A Basic 3D Printing process and a 3D Printer

The building process can be explained in three steps:i. Pre-processing:


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- Firstly, the CAD model of the object to be built is prepared.- The CAD model is then converted to STL file format. - The STL file is then checked and if any errors are found it is repaired by the

STL file repair software.- After the input file is repaired, it is send to the RP system and it is sliced

there by the Z - print software.- Now the input file of the object to be built is ready and is sent to the 3D

printer.ii. Building:

- The machine spreads a layer of powder from the feed box to cover the surface of the build piston.

- The printer then prints binder solution onto the loose powder, forming the first cross-section.

- The binder used consists mainly of starch or gypsum plaster, some dyes (color) and water.

- Formonochrome parts, the printer uses all four print heads toprint a single-colored binder. For multi-colored parts, each of thefour print heads deposits a different color binder, mixing the fourcolor binders to produce a spectrum of colors that can be applied todifferent regions of a part.

- The loose powder is glued together by the binder at where it is printed by the principle of adhesive bonding.

- Theremaining powder remains loose and supports the layers that willbe printed above the already built layer.

- When the cross-section is completed, the build piston is lowered exactly by one layer thickness, anew layer of powder is spread over its surface, and the processis repeated.

- The part grows layer by layer in the build piston untilthe part is completed.- Finally the build piston is raised and the loose powder thatcompletely

surrounds and covers the final partis vacuumed, revealing the completed part.iii. Post-processing:

- Once a part is completed, theparts are lifted from the bed. - Then the parts are finishedin a variety of ways as per the requirement. - For a simple visualizationparts can be left raw or green.- To give strength to the parts, they can be dipped in wax or for more robust

models the partscan be infiltrated with a resinor urethane and further operations like sanding,finishing, painting etc. can be done.


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Home Work:1. Write down about the 3D Printing process.2. Watch 3D Printing process

Weblink: https://www.youtube.com/watch?v=R-JOJ91p9Wchttps://www.youtube.com/watch?v=7QP73uTJApw

Day – 181. Write downabout the current three Dimensional Printing (3DP)models

and their specifications.Ans:The first commercialized 3D Printer is Z – 402. It was a monochrome model. Later on number of models with upgraded technique came to market. The current 3D Printers are,

1. Z – Printer 310 Plus:- This is a upgraded version of entry level printer Z – 310- It’s key features are

High Definition (HD) printing Heated build chamber – it helps in shortening build time by 25% Advanced firmware – it helps in smoothening the finish of the part and

enhancing the build resolution by 50%2. Z – Printer 450

- Multi-Color 3D Printer- This printer has completely automated operation such as:

Automatic set up Powder loading Self-monitoring of materials & print status Automatically removing and recycling loose powder Quick change material cartridge

- All these automated operations reduce touch time by 40%, hence shortening the part developing time.

- It also has a single tri color print head instead of multiple print heads, hence reducing cost and enabling around 60% faster changes.

- Some more features of the printer are as given below: Quite operations Zero liquid waste


https://www.youtube.com/watch?v=7QP73uTJApw

https://www.youtube.com/watch?v=R-JOJ91p9Wc

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Powder, binder & ink levels can be monitored remotely3. Spectrum 510

The main characteristics of this printer are as given below:- High definition (HD) 3D Printer- High fidelity – accuracy with which a system reproduces the image of its

input signal- 24 - bit color – means approximately 16.7 million variety of color can be

produced in this 3D printer- 600 × 540 dpi print-head resolution- Large build size – 10 × 14 × 8 cubic inches- Improved surface finish- Lower operating cost- Vibrant color capabilities – that allows better representations of assembly

The specifications of all the available models are given below in table -2.Table 2Summary of specifications of Z – Corporations 3D printers

ModelsZ Printer 310

Plus Z Printer 450 Spectrum Z 510

Build speed 2 – 4 layers/ min.Build size (in inch3) 8 × 10 × 8 8 × 10 × 8 10 × 14 × 8

Material used

High performance composites, elastomer,

direct casting & investment

casting

High performance composites

High performance composites, elastomer,

direct casting

Layer thickness (mm) 0.089-0.203 0.089-0.102 0.089-0.203Resolution (dpi) 300 × 450 300 × 450 600 × 540

Number of print-heads, jets

1 print-head304 jets



CAD Interface STL, VRML, PLYSystem software Z Print

Equipment size (mm3) 740×860×1090 1220×790×1400 1070×790×1270Equipment weight (kg) 115 193 204

Power Supply 115 V, 4.3 A or 100 V, 14.4 A or 100 V, 7.8 A or


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230 V, 2.4 A 115V, 14.0 A or 230 V, 6.2 A

115 V, 6.8 A or 230 V, 3.4 A

Homework:1. Search aboutdifferent 3D printer models available currently.

Web Links: www.3dsystems.com2. Write down the technical specification of a 3D Printer. (8 Marks,

Supply Exam, Nov – 2016)Day – 19

1. What are the main principles involved in 3D Printing?The important principles of the 3D Printingare as follows:i. Adhesive bonding

- Each layer of powder material is converted to solid mass by the adhesive bonding principle.

- The print-head deposits a binder solution that contains additives or binder material, water and dyes.

- When the binder droplet impinges the powder particle they form adhesive bond and a spherical agglomerate of powder and binder particle is created.

- Because of the capillary action the nearby powder particle also get embedded in the spherical aggregate.

- The capillary forces will also cause the powder particle in the previous layer to merge to the aggregate formed.

- This will cause a solid network that will result into a solid model.- The energy needed for the adhesive bond formation is very low and it

comes from the liquid binder droplets.- Thisbinding energy is around 104 times lower than sinter bonding energy.

ii. Layering technique- The bonding between the powder particles of each layer as well as the

adjacent layer occurs because of adhesive bonding. - After one layer of powder solidifies, the build piston moves down by one

layer thickness and the roller spreads the next fresh layer of powder from the feed box over the solidified layer.

- The print-head then selectively deposits binder solution on the powder layer as per the slice data.

- The layering continues till the object is complete.iii. Support structures


http://www.3dsystems.com/

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- As all the RP system build the part from bottom to top, support structure for undercuts and over hanging are essential for all techniques.

- For 3D printing technique the support to next layer is combinedly given by solidified powder mass and the unsolidified powder of the previous layer.

- As additional support structure is not required for this process, therefore support generation by Zprint software is not required.2. What are the process variables involved in 3D Printing?

Ans:The factors that influence the performance and functionality of 3D printed parts are,

i. Properties of the powder(Viscosity, Stiffness, Thermal conductivity, binding characteristic)

ii. Properties of the binder/ additive(Viscosity, Stiffness, Thermal conductivity, binding characteristic)

iii. Accuracy of X-Y positioning tableiv. Accuracy of the elevation system(Z – height control)

Homework:1. Study about the Adhesive Bonding Process.

Day – 201. What are the materials used in 3D Printing process?

Ans: As we know 3D Printing is a powder based process, the material used here is in powder form. All the material used in process can be categorized into five types as given below.

i. High performance composites- These materials can be used to make strong, high definition parts.- It is made up of heavily engineered plaster material and additives to

maximize surface finish, feature resolution and part strength.- This material is ideal for high strength requirements, delicate parts, color

printing and accurate representations of design details.ii. Snap-fit material

- This material is specially designed for infiltration with Z – Snap epoxy to create plastic like parts.

- It is a plaster based system that produces 3D printed parts with a more porous matrix allowing them to absorb large quantity of Z – Snap epoxy.

- This material is best suited for snap – fit applications.iii. Elastomeric material


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- This material is specially designed for infiltration with an elastomer to create parts with rubber like properties.

- The material system consists of cellulose, fibers and additives.iv. Investment casting material

- This material is used mainly for fabricating parts that can be dipped in wax to be used as investment casing patterns.

- This material system is also made up of cellulose, specialty fibers and additives.

- The components are so chosen so as to maximize the absorption of wax and minimize the residue generated during burn-out process.v. Direct casting material

- This material is used to produce sand casting molds for nonferrous metals.- The material is a blend of foundry sand, plaster and additives that provides

strength to the mold, temperature resistance and good surface finish.Day – 21

1. What are the strengths and weaknesses of a 3D Printing process?Strength:- High speed – The 3D printers are High Speed (HS) printers. Each layer is

printed in seconds reducing the prototyping time.- Versatile – Parts made from 3D printing can be infiltrated with variety of

materials, thus creating a range of products with variety of material properties. The parts are currently used for automotive, packaging, footwear, medical, education, aerospace and telecommunication industries.

- Simple to operate – The 3D printing machines are very simple to operate. The complete automation eliminates the need of any technician to operate the machine.

- Minimal wastage of materials – The unused powder in each process can be collected and can be reused to make the next part.

- Colorful parts – The 24 bit color palette used in the 3D printer helps to create vibrant colorful parts.

Limitations:- Limited functional parts – As compared to SLS process parts made by 3D

printing are very weak and hence used for very limited applications.- Poor surface finish – 3D printed parts have very poor surface finish and

hence post – processing operations are required.


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2. What are the applications of 3D printingprocess?

3D printed models can be used in the following areas:1. Concept models– 3D printed colorful parts resemble the actual partto a

great extent and hence used for physical representations, review design ideas, form and styles.

2. Functional model –The green 3D printed parts lack strength to be used for functional applications but those green parts can be infiltrated with varieties of materials and can be used for some functional applications.

3. CAD-casting metal parts – CAD-casting is a casting process where the mold is fabricated directly from a computer model with no intermediate steps. In this step a ceramic shell with integral core can directly be fabricated from a computer model and thus streamlining the casting process.

4. Direct metal parts – A range of metal parts such as stainless steel, tungsten and tungsten carbide can be created from metal powder with a 3D printer. Then the post processing operation likedebinding and sintering can be performed on the parts to increase the density of it.Note:Debinding – This is a controlled process to remove binder material used in the raw material along with the metal powder.Sintering – It is the process of heating a material to its glass transition temperature that brings the solid material to jelly like condition. This process helps in reducing the porosity in the part and increases its density.

5. Structural ceramics – Structural ceramics are ceramics parts specially created for mechanical loading applications. Using Alumina powder and latex binder dense alumina parts can be 3D printed. The green parts are then isostatically pressed and sintered to increase the density of the component. Thermal decomposition is done to remove the binder particles.Note: Isostatic pressing – It is a process used to reduce porosity and increase density of a part by subjecting it to pressure.

6. Functionally gradient parts–These are materials with varying composition and structure gradually over the volume that results in gradually varying material properties. Such parts can be easily created in


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3D printing. For example, ceramic mold can be 3D printed, filled with particulate matter and then pressure infiltrated with molten material.

Day – 22

1. Explain about a few case studies on 3D Printing.

Sports shoe industry

- The 3D Printer has been used by designers, marketers, manufacturers and managers in the footwear industry.

- Leading athletic shoe companies such as Adidas, New Balance and Wolverine, have used this RP system to reduce prototype development time and communicate in new ways.

- With the introduction of full color printing, appearance of prototypes can be close to the final part, so more comprehensive communication on design can be done.

- As shoe industries face constant changing consumer preferences, they have to react quickly to stay ahead in business.

- With the 3D printer the company got the following benefits lead times are drastically reduced made it easier to bring the shoes to shelves with latest design avoiding an excess inventory

Automotive industry

- Leading automotive companies like Ford, Benteler, F1 Racing and Porsche, have been utilizing Z corporation systems to enhance internal communication on product concepts.

- Functional testing is done on parts printed with Z Corporation’s 3d Printer with the use of infiltration resins.

- Additionally, infiltrants are used to improve the durability, humidity resistance and high-temperature properties of Z Corp.’s parts.

- Z Corp.’s ZCast Direct Metal Casting process allows engineers to pour metal directly into a mold printed on a Z Corp. 3d Printer and hence eliminating need for pattern.

- Also, Z Corp. parts are used as patterns in investment casting and sand casting processes for production of metal prototype parts.


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Important questions:1. Write down about the 3D Printing process and list the factors that affect

part quality.2. Write down the technical specification of a 3D Printer.3. Write down the main principle involved in 3D printing process.4. Explain the applications of 3D Printing.5. List out the advantages and disadvantages of a 3DP process.6. What are the materials used in 3D printing?7. Compare SLS and 3D Printing.8. Compare FDM and 3DP.9. Write down a case study on 3D Printing.

Day – 23(Part of unit -1 & 2)

1. List out the models and specifications of Stereo Lithography Apparatus (SLA) technique.

Ans: 3D Systems produces a wide range of RP machines. Following are five categories of models available.

1. Viper SLA- It is an economical model- Uses Nd:YV4 laser as the UV source- It has two built-in modes to cater different needs of the user.

Standard mode – used for parts with normal requirements High Resolution (HR) mode – mainly used for parts requiring smooth

surface finish, excellent clarity, high accuracy and thin straight walls.2. Viper HA SLA

- It has the same functionality as Viper SLA.- Only additional hearing aid specific enhancement is incorporated in this

model.- Single-Vat Viper HA SLA system can be upgraded to Dual-Vat Viper HA SLA

to produce two different color parts in a single build.For larger build envelope the following three models are available.

3. SLA 50004. SLA 7000

- This model is around 2 – 4 times faster than SLA 5000.- The reason for fast speed is because of the dual spot laser technology that

uses two types of laser beam. A smaller beam spot of diameter 0.01 ± 0.001 inch – to trace the border


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Bigger beam spot of diameter 0. 03 ± 0.003 inch – to crosshatch the internal portion

5. Dual vat Viper Pro SLA system- This is the largest and top series model.- Contains a new configuration called “Dual Resin Delivery Module (RDM)”

that allows user to build parts from two different material simultaneously using a same imaging and scanning module.

- RDM contains a resin management system which will automatically detect and cross check for proper resin type in the system.

- Additional feature of filtration and recirculation of resin material can be done to extend its use.

- Large size parts can be built (29 × 25 × 21 in3) because of two inbuilt chambers.

All the technical specifications are represented in the table – 3. Table 3Summary of specifications of 3D System’s SLA models

ModelsViper SLA Viper HA SLA

DescriptionA dual-resolution,

constant power, longer-life laser

A dual– resolution system with hearing aid specific

enhancementVat capacity

Maximum build envelope 10 ×10×10 in3

Volume (l) 32.2Laser

Type Solid state Nd:YV4

Wavelength, nm 354.7Optical scanning system

Dual spot YesBeam diameter – standard mode

(in.)0.01 ± 0.001

Beam diameter – HR mode (in.) 0.003 ± 0.0006

Recoating systemZeyphr

Interchangeable YesRaghu Engineering College Dept.ofMechEngg. Additive Manufacturing Unit-III

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vatSmart-sweep NoAuto resin fill No

Table 3Summary of specifications of 3D System’s SLA models (contd.)

Models

SLA 5000 SLA 7000 Viper Pro SLA system

Description A large size system

A large system two times faster than SLA 5000

A system with excellent build

speed, adjustable beam size. Can built parts with two different

materialsVat capacity

Maximum build envelope 20 × 20 × 23 in3 20 × 20 × 23 in3 29 × 25 × 21 in3

Volume (l) 253.6 935Laser

Type Solid state Nd:YV4

Wavelength, nm 354.7Optical scanning system

Dual spot No YesBeam diameter –

border (in.) 0.01 ± 0.001 0.01 ± 0.001 0.005

Beam diameter – hatch (in.) 0.01 ± 0.001 0.03 ± 0.003 0.03

Beam diameter – speciality (in.) Nil Nil 0.012

Recoating systemZeyphr

Interchangeable vat Yes

Smart-sweep YesAuto resin fill Yes

Day – 24Raghu Engineering College Dept.ofMechEngg. Additive Manufacturing Unit-III

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1. List out the models and specifications of Solid Ground Curing (SGC) technique.

Ans: The technical specifications of CubitalInc’sSolider system in given below in the following table.

Table 4 CubitalInc’sSolider system

Model SoliderIrradiation medium High power UV lampXY Resolution (mm) Better than 0.1

Surface definition (mm) 0.15Elevator vertical resolution (mm) 0.1 – 0.2

Minimum feature size (mm)

0.4 (horizontal, X-Y)0.15 (Vertical, Z)

-0.4(horizontal, X-Y)0.15 (Vertical, Z)

Work Volume XYZ (mm × mm × mm) 350 × 350 × 350 – 500 × 350 × 500Production rate (cm3/h) 550 – 1311

Minimum layer thickness (mm) 0.06Dimensional accuracy 0.1%

Size of unit, XYZ (m × m × m) 1.8 ×4.2 × 2.9 – 1.8 × 4.2 × 2.9Data control unit Data Front End(DFE) workstation

2. List out the models and specifications of Laminated Object Manufacturing (LOM) technique.

Ans:LOM technique is marketed by Cubic Technologies. The company offers two models of LOM RP system, LOM – 1015 Plus and LOM – 2030H. Each of these uses CO2 laser. The optical scanning system for delivering the laser beam consists of three mirrors that reflect the laser beam and a focal lens to focus the beam to about 0.25 mm (0.01 in.). The detailed specifications of both the models are given below in table 5.

Table 5 Cubic Technologies’ LOM systems

ModelLOM – 1015 Plus LOM – 2030H

Maximum part envelope size, (in.)

15 × 10 × 14 32 × 22 × 20

Maximum part weight 32 204


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(kg)Laser type CO2 laser

Laser power 25W 50WLaser beam diameter (in.) 0.008 – 0.010

Motion control systemServo based X – Y

motion system with speed up to 18 in./s

Brushless servo based X – Y motion system with

speed up to 18 in./sPart accuracy XYZ

direction, (in.) ± 0.005 in.

Material thickness (in.) 0.003 – 0.008

Material size Up to 14 in. roll width and roll diameter

Up to 28 in. roll width and roll diameter

Floor space (ft) 12 × 12 16 × 12.

Materials

LOMPaper LPH Series, LPS Series

LOM PlasticsLPX series

LOMPaper LPH Series, LPS Series

LOM PlasticsLPX series

LOM CompositesLGF series

Day – 25

1. List out the models and specifications of Laminated Object Manufacturing (LOM) technique.

Ans: The FDM machines can be broadly categorized into two types:

i. FDM MC machinesii. Dimensions series

FDM manufacturing center (MC) Machines:- Provides a comprehensive range of versatile RP system that are also

meant for direct digital manufacturing- They offer finer feature details, smooth surface, more accurate and

stronger parts.- High end systems are able to produce 3D models for mechanical testing,

functional prototypes and production parts.- FDM MC Machines are supplied with Insight software that imports files in

STL format.- There are four machines in this FDM MC series,


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FDM 200mc FDM 360mc FDM 400mc FDM 900mc

- FDM 200mc and 360mc offer RP and entry level rapid manufacturing using ABS or ABSplus plastics.

- FDM 400mc and 900mc offer wide range of materials including ABS, PolyCarbonate (PC), PC-ABS blend and Polyphenylsulfone(PPSF) with better accuracy, finer finishing and higher repeatability making it suitable for direct rapid manufacturing.

- The details of all the four variants are given in the following table.Table 6 Specifications of FDM MC Series machines

ModelFDM 200mc FDM 360mc FDM 400mc FDM 900mc

Build size, (in.) 8 × 8 × 12 14 × 10 × 10 36 × 24 × 36

accuracy (in.) ± 0.005 in. or ± 0.0015 in. whichever is greaterLayer

thickness (in.)

0.007 – 0.010 0.013 – 0.005

Support structures

Automatically generated with Insight software;

WaterWorks soluble support system

Automatically generated with Insight software;

Soluble support for ABS – M30 and PC - ABS

Size (in × in × in) 27 × 41 × 34 50.45 × 35.25 × 77.25 109.1 × 66.3 ×

79.8

Materials

ABSplus single

material system

ABS-M30 single

material system

ABS-M30, PC, PC-ABS,PPSF

multiple material system

ABS-M30, PC, PPSF multiple

material system

Software Insight and FDM Control Center

Dimensions series:- These are office friendly RP systems meant mainly for concept modeling,

creating product mock-up and has some functional testing capabilities.Raghu Engineering College Dept.ofMechEngg. Additive Manufacturing Unit-III

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- Dimensions series 3D printers are easy to install and use.- These are supplied with Catalyst EX software.- There are five models in this series and depending upon the requirement

users can select from the five models. 768 BST 1200 BST 768 SST 1200 SST Dimension Elite

- The code 768 and 1200 refer to their build size in cubic inch and BST refers to Breakaway Support Technology and SST refers to Soluble Support Technology.

Dimesion Elite- Dimesion Elite has same build size as that of 768 Series - It is capable of building fine features with layer thickness 0.178mm.- It uses a stronger material ABSplus that is 40% stronger than ABS.Details of the machine are given in the table below,

Table 7 Specifications of FDM Dimensions Series machinesModel

Dimension 768 Dimension 1200 Dimension Elite

Build size, (in.) 8 × 8 × 12 10 × 10 × 12 8 × 8 × 12

Layer thickness (in.) 0.010 – 0.013 0.007 – 0.010

Support structures

BST (Breakaway Support Technology)Or SST (Soluble Support Technology)

SST (Soluble Support

Technology)

Size (in × in × in) 27 × 36 × 41 33 × 29 × 45 27 × 36 × 41

Weight (Kg) 136 148 136

MaterialABS or ABSplus in standard natural, blue, fluorescent yellow, black, red olive green, nectarine or grey colors

Only ABSplus

Material cartridges

One autoload 56.3 cubic inch ABS or ABSplusOne autoload 56.3 cubic inch support material


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Software Catalyst EX software

Important Questions:

1. List out technical specifications of 3D printer. 2. Compare LOM with SLS with suitable reasons. 3. Describe the process of Selective Laser Sintering and list the factors that affect the part quality. 4. With a neat sketch, explain Selective Laser Sintering process. Also mention its advantages and limitations. 5. List Advantages and Limitations of Selective Laser Sintering process and discuss each one of them in detail. 6. Write the Applications of Selective Laser Sintering process. 7. Explain the working principle and process of Three dimensional printing (3DP) technique. 8. List Advantages, Limitations and Applications of Three dimensional printing (3DP) technique.9. Write the Applications of Three dimensional printing (3DP) technique.

IV B.Tech Mechanical Engineering Additive Manufacturing Third Unit- Assignment - 3Topics covered: Powder based Rapid Prototyping Systems : Selective Laser Syntering (SLS), Thee Dimensional Printing (3DP) 1 a) List out technical specifications of 3D printer. b) Compare LOM with SLS with suitable reasons. 2 a) What are the factors that influence the performance of the 3D printing process? Explain in detail. b) What are different types of materials available for the SLS system? What are their respective applications?3. a) Describe the working principle of three dimensional printing along with its advantages. b) In detail explain about process details and machine details of 3-D printing. 4. a). Differentiate between direct and indirect SLS? b) Why post processing is required in powder based SLS?


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5. Enumerate the basic process capabilities and types of printing in 3D Printing?


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